Wildlife endure winter’s long cold season
PHOTOS BY GARRY BRANDENBURG — Canada geese use a technique to help keep their feet warm. They tuck one leg into their belly feathers while balancing and standing on the exposed leg. What looks like a flock of one-legged geese is just a chance encounter of lots of relaxed geese. They are adapted to winter weather by remaining as inactive as possible. That uses less body fat and helps endure a long winter season. Waterfowl legs and feet do not freeze because arterial blood flow away from the heart is warm and bypasses closely spaced veins taking blood back to the heart. Heat is exchanged from the arteries to the veins. Today’s images were made at Marshalltown’s Riverside Cemetery.
Winter can be a difficult time for wildlife survival. Yet Mother Nature has provided every species that remains in cold country with adaptations to make it through a long cold winter.
Adaptations include accumulated fat layers from which nutrients can be pulled as needed. By springtime, fat layers may be much less but new spring plant growth and warmer weather will be welcomed.
Many small mammals hibernate. Ground squirrels fit this scenario, and so do groundhogs. Other small mammals may just stay underground below the frost line and take long naps without really going into full hibernation mode.
Inactivity reduces nutrient needs and since there is little vegetation to eat anyway at the surface, it is best to not try. Spring will come in due course.
Eagles will seek out carrion, or fish, or if they spot an injured waterfowl, will use the opportunity to eat what is available. We have a good number of local bald eagles that will search the Iowa River for fish.
Eagles also have the ability to fly to open water areas where fish may become vulnerable if they swim too close to the surface. Three Bridges County Park is one such area where water stays ice free as it passes over the old rocks of the former dam.
If one drives to Lake Red Rock, below the dam, little fish called shad are an almost guaranteed source of fish to eat. The shad may be stunned by passing through the water outlet gates of the dam.
Not to be outdone, I have seen bald eagles in open country far from water, and when I ask myself why an eagle would be in the middle of nowhere, I can only speculate that the big bird is just covering a lot of territory to find something to feed itself. They make it happen.
We have a lot of deer in Iowa. Even after the hunting seasons have taken out over 108,200 animals, the remaining deer numbers are sufficient to provide a breeding population capable of replacing hunting season losses.
Now during the cold of winter, deer are finished with the rut, feel less pressure to move about, and by remaining relatively inactive, preserve heat inside their big bodies, and they are living in part of the fat layers they accumulated from last summer and fall.
A biological principle of why warm-blooded vertebrates (think deer, elk, caribou, moose, bison) have large body size is to allow them to be more efficient at retaining heat. As an animal gets bigger, its surface area increases as a square but its volume increases as a cube.
The bigger the animal, its volume increases way more than the surface area. Internal body heat is easier to retain.
If one looks at the natural history and adaptations of ice age mammals, for instance, the bison of long, long ago were way bigger bodied than today’s plains bison. Since the ancestral bison had to live during short summers and very long winters in the short grass steppes of recently de-glaciated landscapes, their adaptations to post ice age climates dictated the efficiencies of large bodies.
Those larger bison species, about 5 or 6 to be more specific, gradually became extinct as the naturally warming climate began to dominate after the last ice age. Bison bones found at archeological dig sites tell of these animals not adapting to the changes. Our modern smaller bodied bison proved to be the winning ticket as the interglacial warm period of the northern hemisphere dominated.
Whitetail deer live year round in northern Canada and in many mountainous territories of the United States. They have large body sizes up north, and as one moves south through the Midwest and into the southwest or southern states, deer bodies are generally smaller.
Those southern deer live in warmer climates. The tiny Coues deer (pronounced cows) of Arizona or Mexico is one example. The key deer of southern Florida is another instance of small body size.
An Iowa doe deer going into the winter season might have 30 percent of her body weight as fat. Fat is stored energy and it also works as an insulation layer.
Having enough fat is part of the insurance package for the pregnant doe deer to allow sufficient growth of her unborn fawn or fawns. When the fawns are born in late May or early June, their nourishment is dependent upon a healthy doe deer. She remained healthy by the careful balance of living off her fat reserves prior to the greening up of new spring vegetation.
During winter, deer, being browsing animals, eat twigs and buds and other more scarce foods. What they eat may help but those nutrients must be supplemented by using her fat reserves in combination to hold her over toward spring. The stomachs of deer in winter may contain lots of
browse materials however the energy content is low both in calories and protein.
Deer legs are long and thin. They must be able to run fast to avoid predators, and within their legs is the countercurrent heat exchange from arterial blood to vein blood as these vessels lay beside each other within the legs.
Deer hooves are virtually bloodless so no thermal needs are required. Unlike people, we need mittens or gloves of the right size and materials to keep our fingertips warm during cold weather. Deer also have a winter coat of hairs that includes a dense underlayer of soft hairs and longer outer hairs that are hollow.
These insulation factors help retain body heat. In summer, a deer’s hair coat from winter is shed, and its summer hairs are not hollow. The soft underlayer is not present. This equates to us taking off a sweater in the summer and putting it back on in late fall and winter.
Winter can be difficult but not impossible for wildlife survival. Mother Nature has it figured out. We can learn from her nature school if we spend the time to observe and study her ways.
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A photo contest is offered again this year by the Marshall County Conservation Board. The deadline for entries is Tuesday, Jan. 31 at midnight. All entries offered for this contest must be done electronically by email to mccb@marshallcountyia.gov.
Note in each submitted image the category you wish to have the image entered, your name and address, phone number and any brief description of what your images are all about.
Photo categories are as follows: scenic, with obvious natural resource connections; Native Wildlife; Native plant life; Open Nature; and lastly Outdoor Recreation. Enter images that you made last year, and see if you could be declared a winner to receive a $20 gift certificate.
Judging will be conducted on Feb. 5. Then, between Feb. 5 and Feb. 11, all the image category winners will be posted on the website so that viewers can pick a people’s choice award. Look up the finalists’ images on https://www.marshallcountyia.gov/510/Annual-Photo-Contest.
There will not be a chili supper associated with the photo contest this year. Just submit images you like electronically and then wait to see how the competition develops in each category. Certificates will be mailed to the winners.
The wide array of excellent images from past years’ contests attests to the quality of outdoor experiences local folks have experienced. One way to beat winter time blues is to go through your collections of images.
Pick the best of the best. Then make an entry in the contest. Good luck.
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Henry David Thoreau said “Live each season as it passes. Breathe the air, drink the drink, and resign yourself to the endurance of the Earth.”
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Garry Brandenburg is the retired director of the Marshall County Conservation Board. He is a graduate of Iowa State University with a BS degree in Fish & Wildlife Biology.
Contact him at:
P.O. Box 96
Albion, IA 50005
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- PHOTOS BY GARRY BRANDENBURG — Canada geese use a technique to help keep their feet warm. They tuck one leg into their belly feathers while balancing and standing on the exposed leg. What looks like a flock of one-legged geese is just a chance encounter of lots of relaxed geese. They are adapted to winter weather by remaining as inactive as possible. That uses less body fat and helps endure a long winter season. Waterfowl legs and feet do not freeze because arterial blood flow away from the heart is warm and bypasses closely spaced veins taking blood back to the heart. Heat is exchanged from the arteries to the veins. Today’s images were made at Marshalltown’s Riverside Cemetery.
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