nocturnal – Discover-Nature

Sounds of the Season

It is late summer, heading into fall, and now is the time of year that the afternoons and evenings grow noisier. Some of the loudest species we hear throughout the year are currently active, calling to maintain contact with family members, to warn of impending threats, or to seek mates.

Singing insects are out at all times of the day and night. Crickets, katydids, grasshoppers, and cicadas four insect families active from late afternoon through the nighttime hours. These species all produce calls using a process known as stridulation. The edge at the base of a front wing, called a scraper, is rubbed across the base of the opposite wing, which has a bumpy surface called a file. This movement can produce buzzing or chirping sounds as well as melodic tones.

^{Annual cicada, Neotibicen spp., by Tony Cheng, Sep 2013}

Annual cicadas, Neotibicen spp., are a large insect averaging two inches in size with brown, green, or black bodies and white undersides. Adult males find spots among the branches of trees and woody shrubs where they can hang out and call for a mate. Calls can be heard throughout the day as a loud buzzing for several seconds that slowly fades to silence. Cicadas get louder with warmer temperatures towards late afternoon but cease all calling as dusk settles.

^{Common true katydid, Pterophylla camellifolia, male & female by TJWalker, U of FL}

^{Grey bush cricket, Gryllidae spp., by LHG Creative Photography, Jul 2010}

^{Grasshopper by Peter Miller, Nov 2020}

Katydids, Pterophylla camellifolia, are well-camouflaged with long, green wings that look much like the leaves of the plants they hide in. Despite their appearance, katydids along with crickets, from the family Gryllidae, and grasshoppers, from the family Acrididae, cannot fly. Katydids choose to occupy branches in tall trees, while crickets and grasshoppers prefer lower vegetation, including tall ground cover, from which to call for a mate. These insects will call well into the night on warm summer evenings, but quickly fade away once temperatures start to drop.

^{Common true katydid male, Pterophylla camellifolia, Carter County, MO, OSF-online}

^{Jumping bush cricket, Hapithus saltator, two calling by Daniel Parker, Sep 2023}

Many of these calls are among the loudest made by wildlife. A sound chamber, made by bowing out the wings from the body to create a hollow space, serves to amplify the sound. From the high-pitched melodic notes of the katydid to the chirping of crickets and grasshoppers, these calls can resonate and carry long distances.

^{Great Horned Owl, Bubo virginianus, by Frank Lambert, Dec 2016}

^{Eastern Screech Owl, Megascops asio, by Paul Driver, Sep 2023}

Against this background, we may also hear night birds, especially owls. In northern Illinois, great horned owls, Bubo virginianus, produces a series of low-pitched hoots to warn off territorial invader, call to a young one, or attract a mate. Eastern screech owl calls, Megascops asio, utter a long trill, lasting three to six seconds. Owl’s calls are easy to recognize and can be heard over long distances, making them an effective method of communication in the dark.

^{Coyote, Canis latrans, by Paul Marvin, Apr 2012}

^{Northern Raccoon, Procyon lotor, by Paul Driver, Sep 2010}

Other sounds that you may hear at night include coyotes, Canis latrans, using yips and barks to maintain contact with other individuals, or by young when begging for food. Long, drawn out howling is used to mark territorial boundaries and is often heard in response to emergency vehicle sirens, which we think are perceived as threats by coyote populations. Raccoons, Procyon lotor, are another species that is very active during the late nighttime hours approaching dawn. If they are close by, you may hear purring or chittering sounds used between adults and their young. Whether alone or in a group, when they are startled, raccoons will aggressively defend themselves and other family members emitting loud barking noises. Screams and growls between fighting individuals are often heard.

Late summer evenings can be quiet and slow or full of noises and events. Taking time to walk or sit quietly in your own backyards and listen can be a rewarding experience. Come to the Jurica-Suchy Nature Museum or visit your local nature center to learn more about wild nights in your area.

^{Clockwise: Coyote, Canis latrans, by Paul Marvin, Apr 2012; Eastern screech owl-red morph, Megascops asio, by Laura M, Feb 2023; Great-horned owl, Bubo virginianus, by Don Miller, Jul 2016; Raccoon, Procyon lotor, by Alex ONeal, Aug 2010; Raccoon, Procyon lotor, by Ellya Selhub, Jan 2006}

Squirrels of Illinois

Squirrels are members of the family Rodentia, along with about 40% of all mammals species including mice, rats, voles, beavers, muskrats, guinea pigs, and hamsters. Rodents are characterized by the two front teeth on both the upper and lower jaws that grow continuously their entire lives.

^{Note incisors on left strike against each other to remain sharp; Molars grow in back of mouth}

^{Rodent dental system by V. Leche, professor Stockholm hogskola}

^{Guinea pig incisors by Morbakka, Oct 2024}

Squirrels in Illinois can be found in forested areas as well as urban communities. They all use their long tails for balance when climbing trees or resting on branches as well as running along branches, wires, and tops of walls. Squirrels are excellent climbers and can jump up to ten feet. They are able to gnaw and chew through almost any non-metal material.

^{Grey squirrel jumping to a fence top by AJ, Nov 2017}

Most species are solitary dwellers, but not territorial, able to live on their own, but in close association with other squirrels, rarely fighting for territory, food, or mates. They breed twice each year, once in winter and once in early summer. Two to four young are typically born and can fend for themselves after about two months. The young will often stay with the mother until the next litter is born.

Squirrels use tree cavities for raising young and for protection from predators, but most of the time they live in nests built of twigs and leaves high up in a tree. Nests are normally located near readily available water. They eat a variety of foods including nuts, berries, acorns, fruit, buds, fungi, seeds, and insects.

^{Fox squirrel by Corey Seeman, Jan 2023}

^{Fox squirrel by Corey Seeman, Jan 2020}

The fox squirrel, Sciurus niger, is the largest species in Illinois at about 22″ in length and weighing up to two pounds. Their fur is reddish-brown, with lighter shades on ears, bellies, and tail edges. They are common in urban areas, but are often found where there are no gray squirrels. Fox squirrels are most active in the early morning and late evening and are excellent swimmers.

^{Grey squirrel by Zoblinski,}
^{Getty Images}

^{Leucistic (white) grey squirrel}
^{by Pete Weiler, Pexels}

^{Melinistic (black) grey squirrel}
^{by Tom GV, Getty Images}

The Eastern gray squirrel, Sciurus carolinensis, is slightly smaller at about 18″ long and weighs about a pound. They have short, gray fur, but are often subject to genetic variations that result in different colored fur. Common variants in Illinois include melanistic or black squirrels, leucistic or white squirrels, and albino squirrels. Eastern gray squirrels are abundant in urban areas and large forested tracks. However, there are very few forests left in Illinois to support these animals.

^{Red squirrel by Christopher Defalco, Pexels}

Red squirrels, Tamiasciurus hudsonicus, are small, about a foot long, weighing about a half pound. They have reddish-brown backs with white bellies and a dark orange stripe down their back in summertime. Red squirrels are found only in the northeast quarter of the state in large forested areas. They are diurnal, active in early morning and late evening.

^{Southern flying squirrel by EEI_Tony, Getty Images}

The Southern flying squirrel, Glaucomys volans, is the smallest species at about nine inches, weighing only two ounces. They have gray-red-brown backs with white bellies and are nocturnal, making them difficult to observe. Flying squirrels have large eyes to see better at night and a long, flattened tail that is used as a rudder when airborne. A flap of skin runs between the front and back legs on either side of their body and is stretched taut when their legs are spread, providing the ability to jump from a high place and glide down to a lower place. Unlike other squirrel species, flying squirrels share a communal nest during most of the year.

^{Northern flying squirrel by Dopeyden, Getty Images______While this is not the species found in Illinois, flight patterns are very similar…}

Squirrels play an important part in forest and urban tree regeneration. They bury acorns and other nuts in warmer months for winter food stores, but usually bury many more than they actually consume. The remainder are left to germinate, resulting in many new trees each year. Squirrels are fun to observe and can provide enjoyment and an opportunity to learn about wildlife behaviors. Come down to the Jurica-Suchy Nature Museum or a nature center near you to learn more about these amazing animals.

Sounds of Spring

Thunder and heavy rain, soft rain and light wind, birds in the early morning, frogs in the evening, and maybe a coyote howl deep into the night are some of the sounds of spring. As cold temperatures ease into summer highs, walks through natural areas tend to be filled with many sights as well as opportunities to learn by being quiet and listening closely.

Calls and songs are used by many species for a variety of purposes. Thousands of birds are migrating through the area, especially on clear evenings, and calls help to keep birds together and establish who is the flight leader. Year-round species are re-establishing territories, using calls to warn intruders to stay away or warn family members of approaching threats. Frog species in particular are calling during evenings to find a mate, lay eggs, and begin the establishment of the next generation.

There are dozens of species active at this time of year, and as we have been taking nature walks on campus the last few days, here are some of the wildlife we are listening to (click on each picture to hear their call)…

^{Yellow-rumped warbler, Setophaga coronata, Mirceax, Getty Images}

Yellow-rumped warbler, Setophaga coronata, by Valerie Heemstra, 2024

^{Red-winged blackbird, Agelaius phoeniceus, by KenCanning, Getty Images Signature}

Red-winged blackbird, Agelaius phoeniceus, by Thomas Ryder Payne, 2022

^{Palm warbler, Setophaga palmarum, by Irving A. Gaffney, Getty Images}

Palm warbler, Setophaga palmarum, by Christopher McPherson, 2021

^{Northern waterthrush, Parkesia noveboracensis, by Carol Hamilton, Getty Images}

Northern waterthrush, Parkesia noveboracensis, by Lance A.M. Benner2017

^{Northern Parula, Setophaga americana, by Neil Bowman, Getty Images}

Northern Parula, Setophaga americana, by Richard E. Webster, 2023

^{Chipping sparrow, Spizella passerina, by Irving A. Gaffney, Getty Images}

Chipping sparrow, Spizella passerina, by David Tattersley, 2023

^{Blue-headed vireo, Vireo solitarius, Mirceax, Getty Images}

Blue-headed vireo, Vireo solitarius, by Thomas Magarian, 2024

^{Blue Jay, Cyanocitta cristata, by Miguel Opacic, Getty Images}

Blue Jay, Cyanocitta cristata, Sue Riffe, 2024

Bird songs have a structure and rhythm, and are repeated often to attract a mate, ward off rivals, or bond with a family member. Other calls give warning that danger is near, keep flocks together in flight, or create a pair bond, often between mother and chick.

Frogs and toads are mating and laying eggs in area ponds. Each species has its own distinctive call, used by the males to attract a mate, warn of potential danger, establish a territory, or to signal distress. Frog species being heard around campus at this time include the following (click on each picture to hear their call)…

^{American Toad, Anaxyrus americanus, by Mshake, Getty Images}

American Toad, Anaxyrus americanus, by Thomas Margarian, 2024

^{Boreal chorus frog, Pseudacris maculata, by Derwyn, Getty Images}

Boreal chorus frog, Pseudacris maculata, by Thomas Margarian, 2016

^{Spring peeper, Pseudacris crucifer by HuntImages, Getty Images Signature}

Spring peeper, Pseudacris crucifer by Paul Marvin, 2012

^{Northern Leopard Frog, Lithobates pipiens, by Jennifer Seeman, Getty Images}

Northern Leopard Frog, Lithobates pipiens, by Paul Marvin, 2015

Sometimes, coyote can be heard when walking in woodlands around campus late in the evening. There are a lot of different calls used by these canines to provide information to other individuals. You can listen below to a bark used to indicate a threat, a social call establishing an individual’s location, a begging call from a young one, and a howl audible over long distances to announce one’s presence. Other calls may include a woof to signal a low intensity threat, a yip to claim territory, a growl to threaten another animal, and a whine or yelp to show subservience to a more dominant individual.

^{Coyote, Canis latrans, barking by TakenPix, Getty Images}

Coyote, Canis latrans, bark by Paul Marvin, 2018

^{Coyote, Canis latrans, begging, by Keith Szafranski, Getty Images Signature}

Coyote, Canis latrans, begging call by Matthew L. Brady, 2025

^{Coyote, Canis latrans, social interaction by Michel Viard, Getty Images}

Coyote, Canis latrans, social call by Flor Sangermano, 2023

^{Coyote, Canis latrans, howling, by Keith Szafranski, Getty Images Signature}

Coyote, Canis latrans, howl by Paul Marvin, 2012

Additional wildlife sounds can be heard on campus around Lake Benedictine or in nearby forest preserves. Get out for a walk and be sure to listen throughout the day for bird species, and into the evening hours for frogs, toads, and coyotes.

Great Horned Owls

The great-horned owl, Bubo virginianus, is native to much of the Americas, including most of North America and Central America and about half of South America. It is the second heaviest owl in North America, right behind the snowy owl, Bubo scandiacus, weighing up to five-and-a-half pounds with a wingspan between three and five feet.

^{Great-horned owl, Bubo virginianus, by Andy Reago&Chrissy McClareen, Aug 2012}

^{Range and distribution of Great-Horned Owl, Bubo virginianus by BirdLife International, 2014}

Feathers cover the entire body, including their feet, and are varying shades of browns and grays. Their backs and heads are mottled or barred in several patches. This coloration, especially when coupled with mostly nocturnal activities, provides excellent camouflage. Their ‘horns’ are actually feathers sticking upwards on either side of their heads. These are called plumicorns, but their function is not well understood. The feather structure of the wing allows owls to fly silently and includes a serrated leading edge to disrupt turbulence and softer feathers behind to help deaden sound.

^{Great horned owl plumicorns by Jean-pol Grandmont, Aug 2013}

^{Great horned owl wing structure by Peter K. Burian, Aug 2015}

The owl’s ears are covered by feathers, but are not symmetrical with one being higher on the side of the head than the other. This arrangement provides the owl with the ability to triangulate sounds and precisely locate prey in the dark or when prey is hidden, such as when an animal is moving about under a layer of snow. Their flattened face, shaped as a round disc, also helps to direct sound to their ears. Like all owls, their eyes are fixed in the sockets, but the bird can swivel its head almost 180° to either side allowing it to see in all directions.

^{Great horned owl talons by Curtis Bouvier, May 2010}

Great horned owls hunt from a perch, observing the area below them before diving swiftly and silently from far above. Their diet consists of small mammals, birds, amphibians, and a variety of snakes. Their talons are powerful and deadly, with a grip comparable to much larger birds such as golden eagles. Most prey is killed by being pierced or crushed in the talons. Owls may hunt and kill for more than their immediate needs and will cache their kills for future meals.

Great horned owls are not migratory. When an owl is ready to mate, courtship occurs in late fall and pairs mate for life, establishing a territory together in which they will live their entire lives. Most territorial defense is through hooting at a transgressor, but rare physical confrontations have been observed. If an owl cannot establish its own territory, it will live in silence among the fringes of other territories.

^{Great-horned owl juveniles, Bubo virginianus, by Alan Vernon, Jun 2010}

^{Great horned owl female & juvenile on nest by John Kees, Apr 2012}

Males are responsible for picking a nest site, almost always taking over a nest constructed by another species. Mated pairs breed once every two to three years, laying from one to six eggs. Egg laying occurs between late February and early April. The female alone incubates the eggs, never leaving the nest, while the male hunts and brings her food. After about 33 days, the eggs hatch. Young owls will start to fly after seven weeks, but take a full month or more to become proficient.

^{Great horned owl calling, Bubo virginianus, by Michael & Katie LaTour, Jan 2019 (at 0:02, 0:10)}

^{Great-horned owl pair calling by Bushman, Dec 2013 (at 0:18, 0:41, 0:51, 1:22)}

Owls are more often heard than seen. Although the females are larger than males, females have a smaller voice box and thus a higher pitched hooting call ending with a slight rising note. Juveniles can make hissing or screeching sounds and are often misidentified as barn owls, Tyto furcata.

You can learn more about these magnificent birds at the Jurica-Suchy Nature Museum. Make a reservation to come see us by visiting our website at: https://ben.edu/campus-links/jurica-suchy-nature-museum/ (click on Register to Visit the Museum).

Bird Song

As spring approaches, many bird species will be migrating across the country from warm winter sites back to summer nesting areas to mate and raise young. For many bird watchers, a favorite activity is to identify birds by their songs. Songbirds have an organ called the syrinx that produces the lyrical notes we can listen to. Birds may produce one or more notes at a time creating complex calls and melodies. Some of these songs are used to attract a mate, or to identify itself to another family member, or as calls of warning about any approaching danger. Night traveling species may use calls to keep the flock together while flying, but most calls are heard throughout daylight hours.

In the upper Midwest, in prairie and wetland areas, the first migrators in early March will include ruby-crowned kinglets, blue-winged teals, loggerhead shrikes, upland sandpipers, and eastern bluebirds. As night time temperatures become warmer and stable, summer tanagers, Baltimore orioles, and up to 35 warbler species will begin moving through this area. Some species to watch for in northern Illinois are American white pelicans, common loons, Northern pintail ducks, and yellow-bellied sapsuckers.

You can find many excellent observation spots in your area by searching online for “spring birding hotspots in your area”. Another favorite forecasting site to follow migrating bird groups is the University of Cornell’s BirdCast Project website.

American white pelican, Pelecanus erythrorhynchos, by Manjith Kainickara, Nov 2010

Call from a young chick by Andrew Spencer, XC36292

Baltimore oriole, Icterus galbula, by Tony Castro, May 2013

Alarm call by Joost van Bruggen, XC864040

Call by Gus Mueller, May 2007

Blue-winged teal, Spatula discors , by Alan D. Wilson

Call by Jonathon Jongsma

Common loon, Gavia immer, by John Picken, Jul 2011

Tremolo call by Darwin Long, Apr 2006

Eastern bluebird, Sialia sialis, by Sandysphotos2009, Apr 2010

Call by Jonathon Jongsma, Jun 2011

Loggerhead shrike, Lanius ludovicianus, by Jeffrey Gammon, Dec 2020

Alarm call by Bobby Wilcox, XC418584

Call by Ed Pandolfino, XC455607

Northern pintail, Anas acuta, by J.M. Garg, Jun 2007

Call by Paul Driver, Feb 2012

Pied-billed grebe, Podilymbus podiceps, by Mdf, 2005

Begging call by José Dellacasa Bravo, XC946741

Nocturnal flight call by David Tattersley, XC811994

Pair contact call by Richard E. Webster, XC971465

Ruby-crowned kinglet, Regulus calendula, by Tony Castro, Jun 2019

Call by Christian Kerihuel, XC814137

Sandhill crane, Grus canadensis, by Jeffery Gammon, Jan 2017

Call by National Park Service, Jan 2004

Left: Summer Tanager female, Piranga rubra, by Gonzalo Zepeda Martinez, Jan 2016

Right: Summer Tanager male, Piranga rubra, by Charles J. Sharp, Feb 2023

Call by Lance A. M. Benner, XC426315

Upland sandpiper, Bartramia longicauda, by Johnath, Jun 2010

Call by Andrew Spencer, XC104334

Yellow-bellied sapsucker, Sphyrapicus varius, by Rhododendrites, Feb 2021

Call by G. McGrane, 2006

At the Jurica-Suchy Nature Museum, our nature journaling club, Nature-Doodlers, will be meeting on March 29th, 10am, at the museum to learn about bird observations, drawing and recording our sightings. Make a reservation to come out to this free event by clicking on the QR Code below:

Salamanders

Salamanders are in the order of amphibians named Caudata, which includes mudpuppies, newts, and sirens. There are about 760 species of salamanders worldwide and 121 species are endangered. With the exception of a few in the Amazon basin, they are found only in the northern hemisphere. They live in habitats that provide sufficient humidity levels to keep their skin moist, from sea level to nearly 15,000 feet in altitude.

^{Northern zig-zag salamander, Plethodon dorsalis, by John P Clare, 2016}

^{Marbled salamander, Ambystoma opacum, by Jupiterimages, PhotoImages}

The smallest species are lungless salamanders of southern Mexico, growing to an inch in length. The largest species are the Chinese great salamanders, about six feet in length. They are often mistaken for lizards, having smooth or bumpy skin, but can be easily identified by their total lack of scales. All salamanders have a tail which is rounded in terrestrial species but slightly flattened and often crested in aquatic species. Most salamanders are grey, brown, or white, but a few terrestrial species are brightly colored. Cave dwelling salamanders often lack all pigment and appear pinkish-white in daylight.

^{* Western lesser siren, Siren intermedia nettingi, by Peter Paplanus, 2013}

^{Long-tailed salamander, Eurycea longicauda longicauda, by Meghan Alessi, Getty Images}

Salamanders, other than cave-dwellers, tend to have well-developed eyes. Research shows they are very attuned to differentiating brightness, but cannot see colors. Their eyes are large and provide nearly 360 degrees of view. Salamanders have no external ears, but can detect vibrations received through their jaw bones. Although some species can emit small squeaks, salamanders have no vocal chords or voice box and do not use vocal communications. Their sense of smell is well-developed and plays an important part in locating prey and mates.

^{* Hellbender, Cryptobranchus alleganiensis}
^{alleganiensis, by Jason Ondreicka, Getty Images}

^{Cave salamander, Eurycea lucifuga, by Alfred Crabtree, 2012}

Salamanders may have functional lungs, non-functioning lungs, or no lungs. All species have the ability to exchange gases directly through their skin and the membranes inside their mouth and throat, but this also requires that the skin remain moist at all times. Terrestrial salamanders depend on moisture found in deep leaf litter, holes in trees in temperate zones, or moisture collected in bromeliads growing on trees in tropical zones.

^{Four-toed salamander, Hemidactylium scutatum,}
^{by Jason Ondreicka, Getty Images}

Salamanders have three sets of glands located under the skin, covering their entire body. Mucous glands secrete a sticky liquid that is spread over their body keeping the skin from drying out. When salamanders are in the water, the mucous acts as a lubricant, enhancing their swimming ability. A second set, called the granular glands, produce toxins and odors unique to each species that helps to deter predators and attract mates. A third set of glands is a mixture of the first two, doing a little bit of the work of each.

^{Small-mouthed salamander, Ambystoma texanum,}
^{by Jupiterimages, PhotoImages}

^{Tiger salamander, Ambystoma tigrinum tigrinum, by John P Clare, 2013}

Salamanders are not as noticeable as many other species. They prefer secrecy and out-of-the-way hiding places. Most species are active at dusk and into the nighttime. All salamanders are carnivorous, feeding on small crustaceans, insects, spiders, and their favorite food – worms. Predators include snakes, lizards, fish, birds, and small mammals. Salamanders defend themselves by exhibiting threatening poses and emitting toxins, many with a bad odor. As a last defense, they may voluntarily lose their tails to a predator, a trait known as autotomy. A new tail can be grown within a few weeks.

Salamanders are easy to care for and their habitats are easily duplicated making them widely distributed in the pet trade and for use in laboratories. Additional conservation impacts come from habitat fragmentation, or habitat degradation, or habitat loss due to draining of wetlands and forest clearing.

^{Northern slimy salamander, Plethodon}
^{glutinosus glutinosus,}
^{by Jason Ondreicka, Getty Images}

^{Red-backed salamander, Plethodon cinereus cinereus, by Steve Byland, Getty Images}

In Illinois, we have 20 species of salamanders, pictured throughout this blog. Seventeen are terrestrial and three are aquatic (*). Consider coming to the Jurica-Suchy Nature Museum or a nature museum near you to learn more about salamanders in your area.

Spotted salamander, Ambystoma maculatum, by Louisianatreefarmer, Getty Images
Blue-spotted salamander, Ambystoma laterale, by Jason Ondreicka, Getty Images
Central newt, Notophthalmus viridescens louisianensis, by Andrew DuBois, 2016
Dusky salamander, Desmognathus fuscus conanti, by Jason Ondreicka, Getty Images
* Mud puppy, Necturus maculosus maculosus, by Andrew Hoffman, 2010
Three-toed salamander, Amphiuma tridactylum, by Peter Paplanus, 2016
Southern two-lined salamander, Eurycea cirrigera, by Peter Paplanus, 2021
Mole salamander, Ambystoma talpoideum, by Andrew DuBois, 2016
Dark-sided salamander, Eurycea longicauda melanopleura, by Andrew Hoffman, 2010

Night Buzzers

Have you had your windows open in the evenings and heard the night noises? Chirping, trilling, and buzzing sounds all provide a delightful background to quiet evenings in autumn. The sounds come from a variety of insect species including crickets, katydids, and cicadas.

^{Riley’s Tree cricket by EdwardSnow, Getty Images}

One method insects use to produce these unique songs is called stridulation. Crickets have a scraper on the edge of one wing and a serrated ridge on the opposite wing. When the scraper is moved across the ridge, a chirp can be heard. Crickets may move their wings slowly creating a continuous chirping sound, or more rapidly, creating a smoother and higher-pitched trilling. Katydid also uses this method with a row of stridulatory veins on the undersides of both forewings. Each row has small teeth-like protrusions. When the wings are rubbed together and the teeth slide over each other, a similar clicking sound can be heard.

^{Tree cricket from Pixabay}

^{Katydid by Pixabay}

^{Cicadas in the forest from Pixabay}

Cicadas use another method involving an organ called a tymbal to creating their unique night buzzing. The tymbal, located on their abdomen, is a pair of ribbed membranes that can be flexed against each other. When they are engaged, a ticking sound is created. When moved rapidly, the continual ticking is heard as a buzzing sound. Behind the tymbal, a hollow chamber in the body is used to amplify the sounds.

^{Speckled Bush Cricket by EVO GT, Aug 2012}

^{Common tree cricket nymph by Vinicius Rodrigues de Souza}

Stridulation in cricket species can only be performed by male crickets. Each species has a unique set of sounds, and there are songs for attracting a mate over a distance as well as a courtship song when she draws near. He may also use a warning sound to ward off any other males infringing on his territory. Tree crickets have long, skinny bodies, live in trees, are nocturnal, and their color is adapted to their habitat. In order to project their call further, they may pull a leaf together around themselves to amplify the sound.

^{Katydid by ElizabethPack, Getty Images}

^{Katydid by Macroworld, Getty Images Signature}

Katydids are nocturnal, from 1/2 to 5 inches in length with a leaf-like appearance that provides excellent camouflage for this tree-dweller. There are over 8000 species in the United States, each with its own distinctive song. Katydids can create everything from soft to loud, harsh sounds. Both sexes can create sound and it is used for many forms of communication. There are songs to attract a mate, songs to warn off potential competitors, songs that provide information about a potential mate, and songs that warn the nearby community of danger.

^{Cicada exoskeleton by GrigoriosMoraitis, Getty Images Signature}

Cicadas create a buzzing sound that can be heard across short distances. Much of the buzzing we attribute to them comes from several individuals together in one area. Songs are unique among each species and used similarly for attracting mates and establishing territory. In addition, a large group of cicadas will use buzzing to drive away potential insect predators who are intimidated by louder sounds including robber flies, mantises, and spiders.

Maybe you will take a stroll this evening, or open your windows for some nighttime air. Be sure to listen for the music in the background of the evening.

^{A night chorus from Pixabay}

Beat The Heat

This week, the weather has been hot for the upper Midwestern U.S. with temperatures topping out above 100°F. Combined with high dew points in the mid-70s, the heat index temperature was upwards of 110°F. Here are some ways that plants and animals keep cool in the extreme heat.

^{Mojave Desert by LezusRocks, Getty Images}

^{Kit fox at entrance to desert den by Stevelenzphoto, Getty Images}

Desert environments, where hot conditions exist daily, are home to numerous animal species that live underground. Heat from the sun penetrates soils and sand layers for several inches, but at 20″ below the surface of the sand in the Mojave Desert, temperatures are fairly constant around 86°F while the surface may be over 110°F. Few large mammals are known to use burrows, although kit foxes and humans are two examples. Basements and lower levels in buildings are often preferred areas on hotter days.

^{Shaded walk in the woods by Felixmizioznikov, Getty Images}

Shade from trees is highly effective in creating cooler areas. Leaves are lighter in color than most soils and paved areas, and leaves reflect much of the sun’s radiation upwards, away from the shady area underneath. Denser foliage and rough leaf textures enhance the cooling effect. Under a shade tree, temperatures may drop up to ten degrees and other surfaces no longer exposed to direct sunlight, including our skin, may be 20 to 40 degrees cooler.

^{African elephant by Petr Polak, Getty Images: Black-tailed jackrabbit by Rancho_Runner, Getty Images; Fennec fox by Nattanan726, Getty Images}

Vasodilation occurs when blood vessels near the skin’s surface expand so more blood flows next to the skin. Many animals living in hotter climates, including fennec foxes, black-tailed jackrabbits, and African elephants, have large ears with broad, flat surfaces devoid of hair, fur, or other insulation. The ear’s large surface area is covered by a thin layer of skin and blood vessels. During hot weather, heat carried in the blood through the ear is readily lost to the outside environment, providing a cooling effect for the rest of the body.

^{Large crowd by Shaunl, Getty Images Signature}

Evaporative cooling is another method through which heat can be dissipated from a body. Trees use this method by losing water vapor through their leaves during photosynthesis, cooling the air under the leaves. Humans employ this method in a process called sweating. We lose warm water through skin pores directly to the air around us. Sweating also moistens our skin’s surface, indirectly providing additional cooling as air moves across the skins surface and wicks away additional heat. An important aspect enhancing the effectiveness of this method is our posture. Being supported by two legs, rather than four, exposes much less surface area to the direct rays of the sun, and much more surface area to air currents.

^{Forest path by Inga Nielsen, Getty Images}

While sweating is good for cooling, it is removing water from the body, which must be replaced for the process to continue. Exposure to today’s temperature extremes may result in a loss of three gallons of water or more from an average-sized human. As you are out enjoying nature during hot days, remember to keep hydrating to stay cool and keep other bodily systems healthy.

Oak-Hickory Forest

Oak-hickory forests makeup one-fourth of all the woodlands in the eastern United States. At the end of the last ice age, oaks were only found in the Appalachian Mountains and the driftless section where glaciers did not form in southwestern Wisconsin. In the last 15,000 years they have repopulated the land from the Mississippi River to the Atlantic coastline.

Clockwise from top left: Quercus alba, white oak by Chris Andrei, Getty Images; Quercus palustris, northern pin oak by Michel VIARD, Getty Images; Quercus rubra, northern red oak by ValerijaP, Getty Images; Fraxinus pennsylvanica, green ash by Garsya, Getty Images; Carya ovata, shagbark hickory by Elmar Langle, Getty Images; Prunus serotina, black cherry tree by Ina Hensel, Getty Images

Oak-hickory forests are an open woodland community where trees make up less than 10% of the plant life. Species of both the red oak and the white oak groups dominate these wood including Northern red oak, Quercus rubra, black oak, Quercus velutina, white oak, Quercus alba, and bur oak, Quercus macrocarpa. Two members of the hickory family, shagbark hickory, Carya ovata, and bitternut hickory, Carya cordiformis, are also found in abundance. These forests are rich with several other tree species most notably red maple, Acer rubrum, sugar maple, Acer saccharum, black cherry, Prunus serotina, black walnut, Juglans nigra, and green ash, Fraxinus pennsylvanica.

^{Arisaema triphyllum berries by ES3N, Getty Images}

^{Arisaema triphyllum, jack-in-the-pulpit by Holcy, Getty Images}

The open structure of the forest supports a large variety of other plants that offer food, shelter from predators and weather, and places to raise a family. Food sources are plentiful including fruit-bearing plants of the genus Vaccinium, which includes blueberries and raspberries, and vines from the genus Vitis, which includes several species of wild grape. Bloodroot, Sanguinaria canadensis, and Jack-in-the-pulpit, Arisaema triphyllum, along with several clovers, attract birds and insects that attract larger predators, creating a rich forest community. It is estimated that oak-hickory forests support over 300 animal species including birds, mammals, insects, reptiles and amphibians.

^{Oak woodland by fotoVoyager, Getty Images Signature}

Oak trees provide a haven for wildlife. Acorns, the fruit of an oak tree, are large and heavy, so they do not spread far from the tree. They offer good nutrition and are a favorite of many wildlife species, whether eaten immediately or cached and eaten over time. Oak trees retain their dead leaves throughout the winter, not letting them fall until early spring. The leaves provide shelter from wind and rain, as well as hiding many smaller birds and mammals from airborne predators. Oak trees have craggy bark providing shelter for insects and other small animals including many amphibian species that overwinter under the bark.

After dying, oak leaves retain tannin, a chemical that slows down their decay. As leaves build up on the forest floor year after year, they create thick layers used by amphibians, reptiles, small mammals, and insects for shelter from predators and weather. In winter, the leaf layer provides insulation from the snow and cold, allowing small animals to move around under the snow, hunting for food, or moving to other sites. However, the leaves can be advantageous to some predators, as well. Owls, and other nighttime hunters, have excellent hearing and can easily detect the sounds from crackling leaves as prey attempts to hide and flee.

^{Gnarled tree with large cavity from wepix, Getty Images Signature}

^{Nature lives forever in fallen trunks by Oleksiy Brunets, Getty Images}

Many tree species are susceptible to dry rot of their interior wood, and none more-so than members of the red oak family. This provides natural cavities for woodland species. Woodpeckers, owls, chickadees, and nuthatches, plus squirrels, raccoons, bats, amphibians, and reptiles all use cavities for shelter and protection. Almost 40% of animal species inhabiting oak-hickory forests will use cavities at some point in their lifetimes. As trunks and branches decay and fall to the forest floor, they create opportunities for food and shelter. In addition, animals drawn to these spaces provide food for larger predators.

As you walk through forested areas over the summer, take note of the tree species and the overall structure you observe Can you spot holes in trees, logs laying on the forest floor, and thicker layers of leaf cover? Are the woods open where you can see possible lanes of movement? What plants have fruit or seeds? Keeping a journal of observations helps us to identify the changes and enjoy these rich habitats.

^{Dry oak forest in springtime by Meinzahn, Getty Images}

^{Swamp oak forest in springtime by Aleksander, Getty Images}

Frog Calling

Spring has arrived bringing rising temperatures, warm winds, and spring rains to the upper Midwest. This is the time of year when many amphibians, most notably salamanders, frogs, and toads, start their annual breeding periods. Illinois has nineteen native frog species. They are secretive and difficult to find most of the year; but spring is the season for mating, and males will leave their woodland homes and make their way to the nearest pond on nights when temperatures stay in the forties or above.

Frogs use a variety of different calls. Advertisement calls, the loudest calls voiced by male frogs, advertises their presence and availability to potential mates. The courtship call, a slight variation of the advertisement call, is used as a female gets close to direct her to the exact location where the male is waiting. If a male mounts an unreceptive female, or mounts another male, which can happen by mistake in the dark, a release call is emitted to inform the male to stop and look for another potential mate. Aggressive calls may be used by one male towards another who gets too close. And if any frogs are attacked by a predator, a loud distress call is made. This may be to startle the attacker or warn other frogs in the area.

^{Waterfall Glen gray tree frogs calling by DonArnold, 2022}

Calls are created by filling the lungs with air, and then blowing out a steady stream of air over the vocal chords. When calling, the mouth and nostrils are normally closed. The air is passed from the lungs, over the vocal chords in the larynx and into the air sac under the mouth. This air sac, shown in many frog pictures, amplifies the sound to help it carry farther. Calling requires considerable energy and may increase the metabolic rate, the rate at which calories are used, from ten to twenty times the resting rate of an individual. For frogs with breeding periods lasting many weeks, the expenditure of calories will cause a male to lose a significant amount of body weight.

^{NoName Marsh, Boreal Chorus & Spring Peeper by DonArnold, Mar 2022}

Many different species of frogs lay their eggs in the same ponds. Males arrive early in the evening and begin advertising, while females arrive a bit later and identify a potential mate based on his call. When a gravid female approaches, the male clasps her from on top and holds on. After a time, the female releases her eggs in the water, and the male immediately fertilizes them by releasing sperm into the water around the egg sac. Depending on the species, all of the eggs may be deposited in one egg sac or in several separate egg sacs. Egg laying can last several minutes to several hours. After each group of eggs is laid, the male and female may separate or rest for a brief period and then move to another spot to deposit more eggs.

Their skin is moist and cool to the touch. It is permeable, allowing air to pass directly through it into their circulatory system, helping to remove some of the workload from the lungs and heart. This can be especially useful during inclement weather. However, the skin’s permeability makes them susceptible to drying out, so they live in or close to water or high humidity environments. Their lifestyle includes being active mostly at night or on overcast days when it is cooler and more humid.

^{From left: Spring peeper calling by Andrew Hoffman, Jan 2000; Ornate chorus frog calling by FWC Fish & Wildlife, Jan 2014; Green tree frog calling by Eyeweed, Dec 2009}

Many frog populations have been impacted by losses of both wetland and forest habitat. Wetlands are used for breeding and forests provide sheltered areas with shade, ground cover, and higher humidity than areas open to bright sunlight. During spring evenings or overcast days, listen closely as you pass by these shady areas and nearby ponds to catch sound or sight of these wonderous small creatures.

Weasels

Weasels are members of the Mustelidae family, a group of carnivores that also includes badgers, otters, ferrets, martens, minks, and wolverines. All species have long necks and bodies with short legs, small, round ears, and thick fur. They are solitary animals that are active year-round, mostly at night. They use strong smelling scents from anal glands to mark their territory and signal other individuals when seeking a mate.

^{Clockwise: Black-footed ferret, Mustela nigripes, by J. Michael Lockhart, USFWS, Dec 2010; American mink, Neogale vison, by Patrick Reijnders; Common badger, Meles meles meles, by Prosthetic Head, Jun 2010; Wolverine, Gulo gulo, by National Park Service, 1968; Pine marten, Martes martes, by John Surrey, May 2015; Eurasian otter, Lutra lutra, by Bernard Landgraf, Jan 2005}

There are five species of weasels native to the Americas. Short-tailed weasels, also-known-as stoats, Mustela erminea and least weasels, Mustela nivalis, are found in the Arctic regions of northern Canada and Alaska. The long-tailed weasel, Mustela frenata, ranges from southern Canada through most of the continental United States to Central America and the northern areas of South America. Two other species of weasels that live in northern and central South America include the Colombian weasel, Neogale felipei, and the Amazon weasel, Neogale africana. The odd species name for the Amazon weasel was first derived from a museum skeleton that had been mislabeled as originating in Africa.

^{Short-tailed weasel, Mustela erminea, summer coat by Steve Hillebrand, USFWS, Nov 2012}

^{Short-tailed weasel, Mustela erminea, winter coat by Steven Hint, Mar 2011}

In summer, weasels are sandy-brown on their backs with light colored bellies and black-tipped tails. Species found in far northern regions molt twice each year, when their fur, except for the tail, changes to white for the winter. They have small heads with long whiskers and small, rounded ears. Necks and bodies are long and slim with short legs. Weasels are found in a variety of habitats from farmland to forested areas, but are often located along an open water source such as streams, rivers, and estuaries. The Colombian weasel has partial webbing of its feet, suggesting a semi-aquatic lifestyle. Long-tailed weasels and Amazon weasels have been observed easily swimming in larger bodies of water.

With their elongated bodies, weasels are able to easily follow prey into burrows, as well as through paths under ground cover such as leaves, snow and ice. Weasels are carnivores, hunting small mammals, birds, insects, and crustaceans. They are generally nocturnal hunters with keen senses of smell and hearing, making them capable predators. The least weasel, with a body between five and ten inches in length, has more biting power than a lion or hyena. A rabbit, its favorite prey, is five to ten times the size and weight of a weasel, but the weasel easily dispatches its prey by gripping the back of the neck to break the spine and kill it. Weasels are excellent climbers, allowing them to pursue prey off the ground.

^{Least weasel, Mustela nivalis by Keven Law, Aug 2008}

^{Least weasel, Mustela nivalis, summer in Alaska by Cecil Sanders, Aug 2008}

Weasel dens are built in burrows abandoned by other animals. A nest of grass and leaves is lined with fur from their prey. Mustelids use a reproductive strategy called embryonic diapause, found in very few mammal species. After conception, the new embryo enters a phase where it remains dormant for a period of time before implanting itself in the uterine wall to begin growth and development. The gestation period can be extended up to a year until conditions are optimal for the survival of both the offspring and the mother. In long-tailed weasels mating takes place in mid to late summer, but babies are born the following spring, when temperatures are warmer and food resources are plentiful and readily available.

Weasels mate in mid to late summer, and young are born the following spring. Kits are blind and deaf for the first two to three weeks after being born, but grow quickly and are weaned between five and six weeks. In most species, both males and females are sexually active before the end of their first summer. In one species, the short-tailed weasel, living in northern areas with short summers, females are sexually mature at two to three weeks while still blind and deaf following birth. Most are sexually mated before they are weaned. Kits will leave the nest to claim their own territory before their first winter.

^{Long-tailed weasel, Mustela frenata, in Seattle Washington by Janis Coralee Leonhardi, Jun 2021}

Most species worldwide are listed as of least concern, with strong populations. An exception is the Colombian weasel, about which very little is known. The first live one was discovered by an amateur naturalist in 2011. There are fewer than a dozen documented animals living in riparian habitats in the cloud forests of Colombia above 5,000 feet. It is thought they are doing well, but too little is known of this relatively new species. The Jurica-Suchy Nature Museum or most local nature museums have wonderful displays of weasels and other members of the mustelid family for you to learn more.

Snake Defense

Snakes, with over 3,000 species worldwide, are one of the largest groups of reptiles. They are found on every continent except Antarctica and live in every type of habitat including freshwater and saltwater. They have numerous enemies and have developed defensive strategies enabling them to survive and prosper.

^{Catching a snake on the wing by CuriousLog, Jun 2007}

^{Red-shouldered hawk with snake by Don Loarie, Mar 2018}

^{Great Blue Heron eating snake by C Watts, Jan 202}2

Snakes must deal with threats from a wide range of animals. Bird species that prey on snakes include raptors, ravens, egrets , and storks. Nocturnal hunters, including owls, have excellent sight in low-light conditions and often hunt by spotting movement among foliage. Likewise, during daytime hours, red-tailed hawks and eagles can spot movement on the ground while soaring. Snakes are normally line-of-sight hunters, and are often unaware of threats from above, giving avian predators a distinct advantage.

_{^{American crocodile, Crocodylus acutus by Florida Fish and Wildlife, Feb 2021; Wolverine by Maia C, Aug 2012; Skunk by D Fletcher, May 2016}}

Most mammal predators are larger, more agile, and faster. Badger, wolverine, and racoon are all excellent climbers and may hunt from an elevated perch. Wolverine and skunk are also burrowers that will dig out their prey from underground. Snakes living in saltwater and freshwater environments are eaten by predators such as crocodiles and snapping turtles. In addition, some larger snake species regularly hunt smaller snakes.

^{Copperhead on dead leaves by Abbott Handerson Thayer, Mar 2022}

Snakes use a number of non-aggressive strategies to avoid confrontation and escape. Their best defense is to remain hidden, using colors and patterns to break up the outline of their body, allowing the snake to blend with the background foliage and be overlooked by any predators. Another passive strategy is balling, involving compressing their body into a tight coil or ball, typically with the head tucked in to protect this most vulnerable area. Playing dead is often an effective means to escape predation, honed to perfection by the Western hognose snake. This snake convulses its body, rolls onto its back, and lets its tongue loll out of its mouth. It may vomit or spew blood, release fecal matter or musk, all in its attempt to convince a potential predator that it is already dead and no longer appetizing.

^{Timber rattlesnake balled and hidden by Peter Paplanus, Apr 2022}

Mimicry is a development that has taken place in some species over long periods of time. Batesian mimicry is when a harmless species has evolved the coloration of a more dangerous species to fool a predator into leaving it alone. Scarlet kingsnakes of the southeastern United States are quite harmless but look very much like Eastern coral snakes, a venomous species in that same area. Auditory mimicry involves creating sounds used by more dangerous snakes. Fox snakes, found in deciduous forests, often vibrate their tails in leaf litter, making a buzzing noise very similar to the sounds made by rattlesnakes living in the same area.

^{Scarlet kingsnake by FWC Fish & Wildlife Research Institute, May 2015}

^{Eastern coral snake by FWC Fish & Wildlife Research Institute, Sep 2014}

Snakes often use one or more methods of intimidation. Bright display colors are found among many venomous species and serve as a warning to potential predators that this snake is dangerous. Another form of intimidation involves a snake inflating its body or a body part to make it look bigger. The puff adder inflates its whole body by filling its lung with air. Cobras hold their heads high and flare out an extra fold of skin on either side of their heads, commonly called “hooding.” Intimidation may also involve auditory cues including the rattling of a snake’s tail and the hiss emitted by cobras as they bring up their heads.

When the above strategies do not allow the snake to escape, most species will not hesitate to strike. Several species do not bite, striking with the nose or an open mouth; however, all venomous snakes will bite in self-defense, although they may not inject venom. A few species are able to spit venom, used purely as an act of self-defense, although if the venom targets an eye or nasal passage, the results can be extremely painful.

Snakes are some of the most interesting species with a lifestyle very different from our own. They have many strategies for keeping themselves safe from wild predators, and will be around for us to observe, learn about, and be fascinated by.

Desert Habitat, pt.3

In the past two blogs, we have explored deserts and the plants which inhabit them. Animals native to these habitats have general adaptations for coping with temperature extremes, aridity, and finding water, food, and shelter. Strategies include hunting during cooler hours including at dawn, dusk, or overnight; obtaining water from sources other than standing water; burrowing underground to avoid temperature spikes and solar radiation; ability to conserve water in their body; ability to dissipate body heat; and being well-camouflaged. Look for each of these adaptations in the following species that live in our desert regions.

Greater roadrunner, Geococcyx californianus, by Tony Cyphert, Sep 2018

Ord’s Kangaroo Rat, Dipodomys ordii, by Andy Teucher, Jun 2005

The greater roadrunner, Geococcyx californianus, can only fly for several seconds at a time, but can reach speeds up to 17mph when running. They hunt early in the morning, retiring to shade when temperatures heat up mid-morning. Water requirements are met from foods including grass and prickly pear cactus, plus prey that includes lizards, scorpions, and rattlesnakes. Roadrunners do not urinate, but can excrete salt and save the water. They have an un-feathered area under their chins used to dissipate body heat. Ord’s kangaroo rat, Dipodomys ordii, is another species that gets all of their water requirements from the seed they eat. Individuals live in underground burrows, coming out only at night to feed. They conserve water in their bodies and do not sweat or pant. They have many predators, but with a 9-foot jump and excellent hearing, they are hard to catch. Seeds are collected and stored in their burrows, and they will gain 50% more water from the underground humidity before being eaten.

Horned Toad, Phrynosomasp., by TJFrom AZ, May 2009

Gila monster, Heloderma suspectum , by Karla Kishinami, Apr 2012

Horned toads, Phrynosoma spp., are small, ant-eating lizards with thick scales to conserve water and deter predators. To escape a predator, these animals can squirt a directed stream of blood from their eyes up to five feet away. They are sandy-colored with undefined outlines allowing them to easily hide amid rocky outcrops. Normally active during the day, they can retreat to burrows or under rocks if temperatures become too hot. During winter, horned toads will spend a period of inactivity, called brumation, in underground burrows. The Gila monster, Heloderma suspectum, is another lizard with armor protected skin marked with black and pink coloration that camouflages them well in sandy soils. They shelter from daytime heat under rocks and shrubs, emerging in early morning or evening to hunt small mammals, lizards, insects, and bird eggs. One of only two venomous reptiles in North America, their venom adversely affects their prey’s nervous system. The short, thick tail stores water in fatty tissue for use when needed.

Tarantula, Aphonopelma sp., by Saguaro National Park, Nov 2020

Western coral snake, Micruroides euryxanthus, by Ashley Wahlberg, Apr 2016

The tarantula, Aphonopelma spp., shelters in deep burrows lined with silk to prevent the sand from caving in. They are nocturnal hunters of insects, arthropods, and small lizards with a bite that delivers a small amount of venom to stun their prey. Venom immediately starts to break down tissue to liquify the meat, allowing the spider to use sucking mouth parts to draw in its meal. The Western coral snake, Micruroides euryxanthus, is brightly colored with red-white-black-white banding and venom that is twice as deadly as most rattlesnakes. They are very secretive, living under rocks or buried in the sand. Coming out at night or on some overcast days, they hunt for lizards and other snakes. Venom causes rapid paralysis and respiratory failure, although due to their small size and small amount of venom injected, they are not a threat to humans.

Like many environments, a healthy desert community exists when plants, animals, and habitat are all present and undisturbed. With much of the life in deserts underground, walking off trails and driving off roads can negatively impact what is under the surface. Removing plants and rocks used for water and shelter is equally damaging. I encourage you to get out, observe, and enjoy this unique habitat, or research many of the fun and interesting adaptations at a local natural history museum.

^{Pictures above clockwise: Bark scorpion by Josh More, May 2014; Cactus wren by Mick Thompson, Feb 2019; Jackrabbit, by Mark Gunn, Mar 2014; Javelina, Sonora Desert, by Richard Bonser, Jan 2005; Tarantula hawk wasp by Jim Mulhaupt, May 2010; Sonoran mud turtle by Grigory Heaton, Sep 2022; Round tailed ground squirrel by Wendy Miller, May 2022; Hoary bat by Michael Pennay, Sep 2009; Cactus deermouse by J.N.Stuart, Oct 2011}