Month: December 2021

Last Minute Gifts

Are you looking for any last minute gifts for someone or yourself who likes to observe nature in the field and wants basic identification and facts without having to carry a full set of field guides?  Flash guides, flash cards, and mini field guides are easy to carry, contain basic information for identifying the most common species, and often have observation tips or facts that will get you started on learning more.

Flash guides are one of my favorites to use outdoors.  They are laminated, fold-out packets that contain full color illustrations and basic identification information for a specific group of species and their habitats.  Small format field guides are paperback books with laminated covers to help protect them in the field.  They cover only the most common species and facts for each.  They are not meant to replace full field guides, but are excellent for quick information.  Both guides can be used in all weather conditions including when wet or muddy, and are easy to clean with a damp cloth.  Guides are lightweight and will easily fit in a vest pocket or shoulder bag.  Flash cards are a similar format, with illustrations on one side and basic information on the other.  Printed mainly as a learning tool, you may still find them useful in the field.

Questions you may want to use to help evaluate a resource may include:

  • Do I want to take it out into the field?  Is it easy to carry? Weather-proof?
  • Does the guide cover the wildlife or habitats I want to observe?
  • Does it contain the most common species I am likely to see?
  • Are illustrations, photos, and drawings easy & sufficient for me to use?  Are field marks noted?
  • Do you only want information on ID, or should it include natural history information also?

Many guides are available through local museums, arboretums, or zoos.  Much of the information on these guides has not changed over the years, so shopping the internet for used guides that may not be currently in print is always a good option.  I use them often in the field for basic ID and to begin learning about the species I am observing as well as the habitats they reside in.  I hope you get out and have fun observing and learning during your own outdoor adventures in the coming months.

A selection of possible guides includes:

Pronghorns

…long distance champs, able to run at 30mph for 15 miles…

The pronghorn, Antilocapra americana, is the only living species in the family Antilocapridae.  All of the animals in this family are native to North America, having diverged from a common ancestor in the giraffe family during the Early Miocene period about 14 million years ago.   During the late 1800s, populations were estimated to be between 50 and 100 million animals, roaming from southern Canada to Arizona and eastern California to the Rocky Mountains.  Fencing of land for ranching and farming severely impacted migration and breeding opportunities.  These restrictions, along with hunting, reduced pronghorn populations to 20,000 by 1925.  Establishing open range areas, including National Park land, and limiting hunting helped the pronghorn population grow back to about a half-million by the late 1900s.

Pronghorn female, white rump flash, Yellowstone National Park, WY by Ala

Pronghorns are deer-like mammals with bright white cheeks, bellies, and rumps against a reddish-tan body.  Their short mane stands erect at 3″-4″ high.  Bucks have a black neck patch and a broad black band running from their eyes to a black nose.  Black horns grow to 12″ for females and up to 20″ on males, curving backward and inward with one prong jutting forward.  Their eyes are large and set out  from the skull allowing them to detect movement at distances of up to four miles.  Teeth grow continuously in response to wear from eating rough grasses and brush.  Pronghorns have hollow-core hairs covering their bodies.  When the hair lies flat, it provides excellent insulation for colder temperatures.  The hair can also stand erect, allowing cooler air to circulate next to the skin during summer heat.

Pronghorn female herd, Yellowstone National Park, WY by Elaine R. Wilson, 2008_fi

Pronghorns live in herds, a lifestyle that has several advantages for non-hunting animals living in flat, open terrain with large predators.  Defense against predators is better when there are more pairs of eyes watching.  More animals together in a herd also means there is the possibility of many fighting back against a predator.  Herds keep males and females in closer contact at breeding time helping to synchronize mating cycles so that all young are born at the same time and can be cared for by many adults.  Pronghorns warn distant herd members of predators by flaring long white hairs on rump patches  that give a flash that is visible over long distances.

Pronghorn male, National Bison Range, MT by Alan D. Wilson, 2008_files

Dominant males establish territories early in the spring and defend these using loud snorts, chasing away competitors, and butting with their horns.  Mating takes place in autumn, followed by seven months of gestation, with one or two fawns born in late spring.  Newborn fawns lie quietly in tall grass, while mother feeds some distance away so as not to give away the fawn’s location to predators.  She will visit each fawn several times a day to nurse.  After 7-10 days, the fawns are strong enough to join the herd.  Pronghorns are active night and day, catching snatches of sleep whenever possible while feeding.  Herds migrate annually, following no set path, but going where food sources are available.  While they avoid mud, rivers and streams are easily crossed as they are excellent swimmers.

Pronghorn male in full stride, Grand Teton National Park, WY by Alan D. Wil

Pronghorns are a unique native species of North America.  The biggest threats to pronghorn today are oil exploration and strip mining as well as roads and fences across migration routes from spring breeding to winter grazing locations.  They have the longest land migration of any species in the United States.  Pronghorns are the second fastest animal on land, able to run at 70 mph for three to four minute bursts,  while the cheetah is faster for short distances, pronghorns are the long distance champs, able to sustain 30 mph for distances in excess of 15 miles.  You can see them at many zoos across the United States, or keep your eyes open as you travel their favorite range in southwestern Wyoming.

Cooper’s Hawks

The Cooper’s hawk, Accipiter cooperii, is a woodland inhabitant and hunter.  In Illinois, they were state listed as endangered from 1977 to 1997.  Since then, with less pesticide use in the environment, we are seeing more of them in backyards here and across North American urban areas.

Cooper’s hawks are blue-gray on the back,  with a black cap, and a belly of white with rufous streaks.  The tail is long and  rounded with black horizontal bars.  Hooked bills for tearing, needle-sharp talons for grabbing prey, and forward-facing eyes providing good depth perception contribute to making this bird an excellent hunter.  They approach stealthily, or sit and watch, then attack with a burst of speed.  Using their tails as rudders, Cooper’s hawks are able to turn quickly and sharply when in flight, giving them outstanding chase and catch abilities while on the wing in a wooded habitat.  Chases can become intense, and several birds have been found to have cracked or broken ribs from encounters with tree branches.

Cooper’s Hawk [back], Accipiter Cooperii by Alan D. Wilson, 2010

Historically, these birds nested in woodlands with extensive canopies and ate songbirds feeding in agricultural row crops.  Many birds have moved to living in urban settings, favoring white pines and oak trees that offer good canopy coverage.  Individuals are loners except at breeding time in the mid-spring.  Males will build a simple nest, and females will lay 2-6 white eggs.  Females incubate the eggs for four to five weeks, then both parents teach the young to hunt.  Juveniles are fully independent and able to live on their own after five weeks.  Egg predation is minimal, with the average clutch losing 25% or fewer of its eggs.  First year mortality rates are high, around 70%, but drop off quickly to 30% for adults.  The average life span in the wild is comparatively long at eight years.  Many birds die from mid-air collisions with wires, autos and windows, especially in urban settings.  Birds are susceptible to a number of bacterial diseases, which may impair the birds’ abilities, but are normally not deadly.

Cooper’s Hawk juvenile on nest, Accipiter Cooperii by Alan D. Wilson, 2012

In Illinois, there are populations that are year-round residents, and there are migrating populations in both spring and fall.  Resident birds may move 50 to 150 miles for short periods depending on temperature and storms, and then move back again.  Spring migrators leave the southern parts of North America headed for breeding areas across Canada for the summer and return in fall to warmer climates.  Our best data on population numbers for this species come from the Christmas backyard bird count and individual watchers journaling their daily observations.

Cooper’s Hawk, Accipiter Cooperii by Robert Adams, 2013

Cooper’s hawks eat small to medium-size birds including cardinals, sparrows, doves, robins, and starlings.  They will also supplement this fare with small mammals such as field mice and squirrels, and other prey including snakes and toads.  With the rise in backyard bird feeding and the restoration of natural areas across the state, birds of prey and Accipiter hawks in particular have become common urban residents.  Two other Accipiter hawks that share habitat and hunting ranges with the Cooper’s hawk are sharp-shinned hawks and Northern goshawks.  These hunters may be considered a natural biological control for larger populations of birds such as sparrows and starlings, but hawks are generalists with their prey and may pose as big a danger to rare birds, as well.

Cooper’s hawks are more active in early morning hours, and they are considered one of the top daytime predators.  As you watch your feeders this winter, be aware of this opportunity to observe a skilled hunter in flight.  They are exciting to observe, sitting close up in a backyards or chasing prey through the trees.

Moon Jellies

Moon jellies are a group of ten species in the genus Aurelia.  They are considered true jellies, but DNA testing is required to distinguish between the species.  They are found in oceans worldwide in shallower waters common in coastal and upwelling areas where prey is more abundant.

Moon jellies have a shallow, transparent, dome-shaped body and short tentacles that hang down from underneath.  Full size adults grow from 12″ to 16″ in diameter.  As with all jellyfish, their body is 95% water, and many of the organs found in other animals are missing.  Jellyfish lack respiratory, circulatory and excretory systems.  They have no lungs, heart, blood, brain, bones, nor teeth.  They do have  rhopalia, small sensory organs found around the rim of the dome, containing statocyst structures that sense gravity to determine balance and depth in the water.

Moon jellies by Eric Kilby at New England Aquarium, 2009

Dietary requirements of moon jellies are not well understood.  Jellyfish are dependent on what the wind and currents bring by to eat.  Stinging cells call cnidocytes cover their tentacles and contain nematocysts that can deliver toxin to immobilize prey.  Moon jellies are predators hunting fish, mollusks, crustaceans, and other small invertebrates.  Food is collected in small pockets along the rim of the dome.  There are four arms that transfer the food to the gastrovascular cavity located in the middle of the underside.  Digestive enzymes break down the food and nutrients are distributed throughout the body by a system of canals.

Moon jelly, Aurelia aurita by James St. John at Lake Superior Aquarium, 2015

Reproduction includes both sexual and asexual processes.  Adult males release strands of sperm into the water which adult females will ingest and use to fertilize their eggs.  She incubates the eggs in pockets located on her four arms.  Eggs hatch and larvae, called planulae, are released into the water.  Planulae  continue to grow and eventually attach themselves to rocks on the ocean floor.  Anchored to the rock, they enter their next life cycle stage known as a polyp.  At this time, they can catch, eat and digest their own prey, and may spend several years as a polyp.  As a polyp, they begin strobilation, an asexual reproduction process whereby a polyp clones itself and buds off the clone to form an ephyra.  Both the polyp and ephyra grow into adult jellyfish.  Through an unknown process, polyps can determine when conditions are ideal to enter their final adult form, called a medusa, through sexual reproduction.  Strobilation allows the population to expand quickly, while egg production guarantees a diversity of genes in the next generation.

Moon jelly, Aurelia aurita by Keppet at Monterey Bay Aquarium, 2013

Moon jellies are social animals, travelling in smacks, large groups numbering in the thousands that float across great distances.  An adult in the wild will live about a year, but may live several years in captivity.  During summer, jellyfish try to reproduce daily.  At the end of summer, with less food available and energy levels waning, many individuals become susceptible to bacterial diseases and die before winter.  In addition, they are food for open ocean predators including ocean sunfish and sea birds.  Leatherback sea turtles feed exclusively on moon jellies, and can eat several hundred at each meal. 

Moon jelly, Aurelia aurita by Roger Myers at Monterey Bay Aquarium, 2003

In areas of increased human activity, moon jellies tend to thrive due to a decrease in competitors for food.  Moon jellies do well in waters with low dissolved oxygen concentrations and high nutrient loads.  When food is limited, moon jellies can shrink to one-tenth of their full size, returning to their previous size as food opportunities become more abundant.  A recent study identified the moon jelly as one of the “immortal jellyfish” groups.  Several individuals have been observed reversing the aging process, becoming younger all the way back to sexual immaturity, and then aging back to adults.  Studies hypothesize that this is an unending cycle.  You can view these incredible creatures at many of the world’s aquariums including the Shedd Aquarium in Chicago.