March 2023 – Discover-Nature

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.

Nuthatches

In northern Illinois, it is still winter, and we have enjoyed watching various birds at our backyard feeders, including nuthatches. There are four species native to North America and about two dozen more found world-wide. Taxonomists have moved several species back & forth between genera in recent years, making the exact number of species vary from time to time. The name is from an English reference to the behavior of wedging a nut into a crevice and pecking at it until the inner portion is hatched and can be eaten.

White-breasted nuthatch, Sitta carolinensis by Mdf, Dec 2005; Pygmy nuthatch, Sitta pygmaea by Len Blumin, Mar 2006; Brown-headed nuthatch, Sitta pusilla by Anne Davis, Nov 2013; Red-breasted nuthatch, Sitta canadensis by Katie Herr, Dec 2013

Nuthatches have short tails and legs, compact wings, powerful bills, and strong claws. Nuthatch species have similar markings including varying hues of grayish-blue wings, black caps, a white throat, and light colored white-buff-reddish bellies. In most species, a dark eye-stripe and white cheeks frame each side of the face. Males and females are hard to distinguish, although males may have darker hues on their bellies.

White-breasted nuthatches, Sitta carolinensis, stand 5″ tall with a white face completely surrounding the eyes. They range from southern Canada to Mexico. Red-breasted nuthatches, Sitta canadensis, have a white face and neck and range from southern Canada to the central U.S. Brown-headed nuthatches, Sitta pusilla, have a white belly and cheeks with a white spot at the nape of the neck. They are found in the pine forests of the southeast U.S. Pygmy nuthatches, Sitta pygmaea, characterized by a white spot under their eyes, are found west of the Rocky Mountains from British Columbia to central Mexico.

White-breasted nuthatch, Sitta carolinensis, heading down by Sarunas Burdulis, Feb 2021
Click > below to listen to the song recorded by Aidan Place, May 2020

Nuthatches are the only birds that can walk head first down a tree trunk, allowing them to forage up or down a tree trunk, seeing insects in crevices missed going the other way. They are comfortable eating while hanging upside down, as are woodpeckers; however, the nuthatch does not use its tail for support relying solely on the strength of its feet. They eat insects and invertebrates when available, but will readily feed on seeds, peanut butter, and suet in colder periods. Food items are often cached in crevices in trees and then covered by lichen or bits of bark.

Brown-headed nuthatch, Sitta pusilla by Shawn Taylor, Mar 2020
Click > below to listen to the song recorded by PT Xiao, May 2022

Nuthatches prefer open woodlands near sea level in temperate climates. In warmer southern regions, they live at slightly higher elevations. They use abandoned woodpecker holes or natural cavities in trees for nesting. Inside, they build a small cup from twigs, lined with soft material for their eggs. Entrances may be protected in a variety of ways. Red-breasted nuthatches collect pine resin to line the rim of the nest hole and avoid it themselves by diving straight into the hole. White-breasted nuthatches often crush blister beetles and rub the remains around the rim, using the foul smell to deter potential predators.

Red-breasted nuthatch, Sitta canadensis by Walter Siegmund, Jul 2008
Click > below to listen to the song recorded by Matthew L. Brady, Jan 2023

Nuthatches are one of only a few animals that use tools. A small piece of bark is often used by red-breasted nuthatches to apply resin to the nest entrance. Bark splinters are also used by brown-headed nuthatches to pry up bark on tree trunks and extract the insects underneath. If the tool performs well, the bird will carry it from place to place. Pygmy nuthatches live in large, extended family groups with other relatives often helping to care for younger birds. They nest in large family groups, huddling together for warmth on cold nights. Red-breasted nuthatch irruptions are common in the central U.S. when the weather turns harsh in Canadian boreal forests, making it difficult to find enough food.

Pygmy nuthatch, Sitta pygmaea by Becky Matsubara, Aug 2019
Click > below to listen to the song recorded by Ron Overholtz, Jan 2019

Nuthatches are a favorite species at backyard bird feeders. They will turn up daily for seeds, nuts, peanut butter, and suet, and are entertaining as they flit in and out, taking food items away to cache in nearby trees or other crevices.

Listen to additional calls and songs for each species at the following sites: White-breasted nuthatch: https://xeno-canto.org/species/Sitta-carolinensis Red-breasted nuthatch: https://xeno-canto.org/species/Sitta-canadensis Brown-headed nuthatch: https://xeno-canto.org/species/Sitta-pusilla Pygmy nuthatch: https://xeno-canto.org/species/Sitta-pygmaea

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.