Life under an icy ceiling

Winter brings hardships for many animals--lack of food, deep snow and cold temperatures. For fish sealed from the winter landscape by a ceiling of ice, the biggest battle isn’t food or cold but oxygen. 

Fish handle colder water by decreasing their activity level which in turn decreases their need for food. By the end of winter, food might be sparse but fish decrease their activity level even more to cope. However, fish cannot cope with running out of oxygen. 

Fish obtain oxygen from the water they take in through their mouths and pass over their gills

Fish use their gills to obtain oxygen from the water much like people use their lungs to obtain oxygen from the air. The oxygen in water is dissolved like carbonation in soda but with smaller bubbles. 

When a lake isn’t capped with ice, oxygen becomes dissolved in the water through turbulence by wave action, waterfalls, rapids, riffles and currents. Oxygen is also released into water by photosynthesis from aquatic plants. 

Once a lake is capped with ice, the lake becomes a closed system. There are no waves to mix in oxygen. The only way oxygen is added is through photosynthesis if the ice isn’t covered with snow. 

If snow blankets the ice, aquatic plants can’t photosynthesize and sometimes will die because of the lack of sunlight. When a plant dies, it begins to decompose and the process of decomposing utilizes oxygen--the same oxygen fish need to survive. 

Snow blocks sunlight from reaching aquatic plants beneath the ice

Even though cold water can hold more dissolved oxygen than warm water, fish will decrease their respiration rates in winter to survive. Unless aquatic plants are able to photosynthesize, the finite amount of oxygen has to be shared by all the fish and aquatic organisms in the lake for the entire winter.

Some fish can tolerate low levels of oxygen better than others. Bass, trout and blue gills tolerate low levels of oxygen the least because they require high levels of dissolved oxygen. Northern pike, crappies and yellow perch have more tolerance for low oxygen levels. Fathead minnows and bullheads can handle low oxygen levels better than most fish.

If all the oxygen is depleted from a lake, no fish can survive. Fish dying due to lack of oxygen in the winter is called winterkill. 

Fish survive the nearly six months of lake ice in some locations by conserving energy through decreased activity, lower metabolic rates and lower respiration rates. With decreased metabolism and activity, digestion slows considerably. Food digested in 24 hours in the summer may take an entire week to digest in the winter. 

The first ice on Roman Nose Lake in mid-October begins a long winter for the fish living below the icy ceiling

Some fish spend the winter in a state of dormancy by moving to the bottom of lakes and seeking shelter under logs, rocks or fallen leaves. A few fish, like carp, go into diapause which is a suspended state with an extremely slow heart rate. 

Cold-loving fish, such as lake trout, whitefish and brown trout, remain fairly active in winter. They tend to venture into new range in the winter that is often too warm and oxygen-poor in the summer, often because it is shallow. 

Each species of fish is different on how it adapts to life below an icy ceiling for several months every year and sometimes the thawing lake edges cannot come soon enough.

Note: Published in the Bonners Ferry Herald on Jan. 30, 2014. 

Thermometers help us define hot and cold

What does cold mean to you: 32 degrees, 0 degrees or minus 20 degrees Fahrenheit? Mid-winter temperatures of 32 degrees Fahrenheit are balmy for someone living in Fairbanks, Alaska but frigid for someone in Phoenix, Arizona. 

Everyone’s idea of cold or hot is relative until it is correlated to a temperature scale. The two most common temperature scales are Fahrenheit and Celsius. Water freezes at 32 degrees Fahrenheit and zero degrees Celsius. 

Fairbanks, Alaska residents routinely encounter temperatures below minus 40 degrees Fahrenheit

No matter which temperature scale is used, the temperature has to be measured in some manner. Thermometers provide a temperature sensor and a means of conveying the information so it is useful to the observer. 

We use thermometers to check the outside temperature, set the thermostat or check the temperature of meat on the grill. There are several different ways temperature is measured. 

The most basic thermometer is the glass bulb thermometer, often with a red liquid inside a tube. In 1709, German physicist Daniel Gabriel Fahrenheit invented the glass bulb thermometer based on thermal expansion.

Under the principal of thermal expansion, when a substance becomes hotter it expands to a greater volume and when a substance becomes colder it occupies less volume. The increase or decrease in volume in a consistent-sized tube is proportional to temperature. 

Glass tube thermometers are calibrated using known temperatures--the freezing and boiling points (212 degrees Fahrenheit) of water. Testing a candy thermometer in boiling water can determine the accuracy of the thermometer.

Meat and patio thermometers with the dial on a circular scale measure temperature through bi-metallic strips. The bi-metallic strips are wrapped into a coil with one end attached to the housing of the thermometer and the other to the indicating needle. The two strips of metal are different and, therefore, expand and contract at different rates in response to temperature. As they expand or contract, the metal bends a certain direction and changes the position of the needle. 

Digital thermometers use heat sensitive liquid crystals to measure temperature. Thermocouples in weather stations and thermostats measure the electrical potential between two different alloys joined together and the difference is related to the temperature.

Other factors influence what the temperature actually feels like to us instead of the temperature indicated on the thermometer. Anyone who has been outside on a windy, winter day knows that the temperature feels colder than what is indicated--a factor known as wind chill. 

Wind chill is based on the rate of heat loss from exposed skin by wind and temperature. More wind cools the body faster and makes a person feel colder. At zero degrees Fahrenheit and a 15 mph wind, the wind chill is minus 19 degrees Fahrenheit. 

Another factor that influences what the temperature feels like, especially during summer, is humidity. High humidity causes those muggy, sauna-like days of summer when sweat won’t evaporate. 

The most common measurement of humidity is relative humidity. Relative humidity is the ratio of how much water vapor is in the air compared to the highest possible amount of water vapor that could be in the air at a given temperature. One hundred percent humidity means the air is completely saturated. 

For people, sweating keeps the body cool and sweat cannot evaporate if the air is saturated. If the relative humidity is low, then we feel cooler than the actual temperature because sweat evaporates more easily. At 75 degrees Fahrenheit with zero percent relative humidity, the air temperature feels like 69 degrees Fahrenheit. Change the relative humidity to 100 percent and the temperature feels like 80 degrees.

Between humidity and wind chill, the temperature we feel outside can vary significantly from what the thermometer indicates, adding more ambiguity to one’s definition of cold or hot.

Note: Published in the Bonners Ferry Herald on Jan. 23, 2014. 

White-tailed deer skull yields rare surprise

After picking up his white-tailed deer skull from the taxidermist this fall, Kody Atkins found out the deer had an uncommon feature--upper canine teeth. The small teeth were located halfway between the molars and the front end of the upper jaw, one on each side. 

A white-tailed deer with upper canine teeth harvested in Boundary County, Idaho

Upper canine teeth are found in male and female elk and are known as ivories, whistlers, buglers, eye teeth or dog teeth. Upper canine teeth in deer are uncommon and even could be considered on the borderline of rare. 

In one study, deer researcher C.W. Severinghaus examined 18,000 white-tailed deer and only 23 had upper canine teeth, a total of 0.01 percent. Other studies have found upper canine teeth slightly more prevalent in southern states than northern states. 

During a study in 1963, the Nebraska Game and Parks Commission checked every mule deer harvested and only two of the deer examined showed upper canine teeth. 

The upper canine teeth are not the meat-piercing canines that are found in the dog family. Instead, the upper canine teeth found in the deer family are vestiges of prehistoric tusks. 

For elk, the upper canines consist of ivory, the same material as the tusks of walruses, wild boars and elephants. 

An elk ivory

The ancestors of modern-day elk and deer once sported large canines in the form of tusks. They used the tusks during rut and as defense against predators because their antlers were not as large as today. 

Over the millennia, elk and deer evolved larger antlers for defense and the upper canine teeth regressed. Elk retain the largest upper canine teeth in the deer family. 

Elk still maintain the ancient behavior of curling their top lip into a “sneer” threat posture to reveal their upper canine teeth. The ivories aren’t as threatening now as they once had been since they have shrunk down to rounded, thumb-tip sized nubs.

There are three deer species in the world that still possess tusk-like upper canine teeth: musk deer, Chinese water deer and muntjacs. Musk deer and Chinese water deer both have upper canine teeth but no antlers. Muntjacs of southeast Asia have both tusks and antlers. 

The upper canine teeth of white-tailed deer are not as large as those of elk

Other members of the deer (Cervidae) family also possess vestiges of canine teeth. Both male and female caribou generally grow upper canine teeth but they typically don’t break through the gum line. Moose normally lack upper canines but a few rare cases of rudimentary upper canines have been reported.

The rarity of upper canine teeth in deer and moose is a factor of genes. The gene for vestigial upper canine teeth is still present in some deer. When a male and female possessing the gene mate, there is a chance the trait will show up in their offspring. Severinghaus even found some does during his study that possessed upper canine teeth. 

They may not be as valuable as elk ivories, but the upper canine teeth of deer are a rare find to be on the look out for when cleaning a skull. 

Note: Published in the Bonners Ferry Herald on Jan. 16, 2014.

Chickadees utilize various tactics to survive

One of the most loyal visitors to bird feeders are chickadees. No matter what the weather, chickadees quickly dart to a feeder, grab a seed and fly back to a safe perch. Most often the chickadees are black-capped chickadees with their familiar black cap, black bib, and gray/white body. However, other chickadees are present in North Idaho and some do visit feeders.

All chickadees exhibit the distinctive cap and bib. Mountain chickadees are similar to the black-capped chickadees except they have a white stripe above their eyes within the black cap. Boreal chickadees sport a brown cap and an overall plumage of dark brown and gray. Chestnut-backed chickadees sport the black cap and bib but have a dark chestnut-colored back and flanks. 

During the winter, black-capped chickadees gain ten percent of their body weight in fat each day just to shiver it off at night

During cold snaps, chickadees seem to feed all day long and for good reason. Staying warm at night is no easy feat for an animal especially small animals. Black-capped chickadees seek out tight cavities to roost in at night and they fluff up their feathers. However, chickadees utilize two more measures to help them make it through the night--they lower their body temperature and shiver.

Black-capped chickadees lower their body temperature from 107 degrees Fahrenheit to 86 degrees at night to conserve vital energy reserves. They also shiver to stay warm. 

Shivering consumes a fair amount of energy and to compensate for the energy needed, chickadees eat a lot during the day. Chickadees in Alaska gain 10 percent of their body weight in fat each day to burn off at night. The human equivalent is a 165-pound person losing 15 pounds by shivering all night and then eating 15 pounds the next day to do the same.

Chickadees consume a large quantity of food in winter. In the fall, chickadees cache food so they do not have to spend precious energy searching for food all the time during winter. In the winter, 50 percent of a chickadee’s diet is seeds and the remainder is frozen insects and spiders. In the summer, a chickadee’s diet shifts to 10 to 20 percent seeds and the remainder is insects, spiders and berries. 

The strong legs of a chickadee allow it to hang upside down while foraging, such as when feeding on the buds at the ends of branches. This acrobatic feeding strategy is only utilized by a few other bird species.

Mountain chickadees look similar to black-capped chickadees except for the white stripe above their eye

Chickadees search the nooks and crannies of trees for spider and insect eggs and larvae, along with caterpillars. In the winter, chickadees form the nucleus of mixed flocks looking for frozen insects. The flocks can consist of chickadees, nuthatches, brown creepers, kinglets and woodpeckers. These birds aren’t typically found foraging together except in the presence of chickadees.

The chickadees will continually call to one another to keep the flock together. Another time when chickadees are extremely vocal is when they are mobbing a predator. 

These faithful feeder visitors may not seem like the type to mob but chickadees are one of the most tenacious and aggressive songbirds when mobbing predators. They take the lead in announcing the presence of a small owl from a nearby perch or strike the owl from behind. Other birds may join in the mobbing to encourage the enemy to move to another area. Mobbed enemies often include small owls, squirrels, raccoons or cats. 

The vocalizations of chickadees can be heard throughout the forest or as close as outside a window, whether they are mobbing a predator, keeping a flock intact or grabbing seeds from a feeder.

Note: Published in the Bonners Ferry Herald on Jan. 9, 2014. 

Outdoor Trivia: What do you know?

To wrap up 2013, I thought I would continue the year-end outdoor trivia quiz I began last year. 

What is this animal? A. Yellow-pine chipmunk B. Golden-mantled ground squirrel C. Columbian ground squirrel

1. Which is not an invasive species?

a. Eurasian collared-dove

b. European starling

c. English Sparrow

d. Black-capped Chickadee

2. Snowshoe hares are coprophagous, meaning they eat their feces to extract additional nutrients. True or False?

3. Moss differs from trees and flowers because of:

a. Lack of water and nutrient carrying system

b. Presence of spores

c. Lack of root system

d. All of the above

4. Which of the following is not an adaptation used by nocturnal animals?

a. Big ears

b. Big feet

c. Big eyes

5. How many eyes do grasshoppers and honeybees have?

a. Two

b. Three

c. Four

d. Five

6. Which tree is a deciduous conifer?

a. Ponderosa Pine

b. Rocky Mountain Maple

c. Alpine Larch

7. Which bird is North America's only aquatic songbird?

a. Belted kingfisher

b. American dipper

c. Marsh wren

8. Benchmarks can be in the form of:

a. Metal discs

b. Chiseled squares

c. Fire lookouts

d. All of the above

9. Turkey vultures have an extremely strong sense of: 

a. Taste

b. Hearing

c. Smell

d. Sight

10. Lightning can strike:

a. Only underneath the cloud

b. Within five miles of the cloud

c. Five to 10 miles from the cloud

d. More than 10 miles away from the cloud

11. Which is not a species of wasp?

a. Bald-faced hornet

b. Yellow jacket

c. Paper wasp

d. Honey bee

12. Which mammal is the slowest reproducer for its size?

a. Mouse

b. Bat

c. Pika

13. Which bird eats more ants than any other bird species in North America?

a. Bluebirds

b. Robins

c. Northern flicker

14. Killdeer draw predators away from their nest by:

a. Nesting high in a tree

b. Nesting in a burrow

c. Using distraction displays

d. Being silent

15. Female painted turtles are larger than male painted turtles. True or False?

16. Crab spiders can catch insects two to three times their size because of their:

a. Camouflage

b. Toxic venom

c. Sharp vision

d. All of the above

17. Which is not a type of honeybee in a hive?

a. King

b. Queen 

c. Worker bee

d. Drone

18. Marsh wrens prey on red-winged blackbird eggs. True of False?

19. Spiders can produce up to how many types of silk?

a. Three

b. Five 

c. Seven

20. Which butterfly is one of the few butterflies to overwinter as an adult?

a. Tiger swallowtail

b. Mourning cloak butterfly

c. Cabbage white

21. When do most owls nest?

a. February/March

b. April/May

c. June/July

22. The diet of a raccoon is:

a. Herbivorous

b. Carnivorous

c. Omnivorous

How did you do?

Outdoor Trivia answers

Photo: B. Golden-mantled ground squirrels resemble chipmunks but they don’t have  stripes on their cheeks like most chipmunks.

1. d. 2. True. 3. d. Moss lacks xylem and phloem, has spores instead of seeds and has rhizoids instead of roots. 4. b. 5. d. Grasshoppers and honeybees have five eyes--two large compound eyes and three simple eyes. 6. c. Alpine larch lose their needles in the fall after they turn golden yellow. 7. b. The American dipper is specially adapted to forage for insects, fish and tadpoles underwater in mountain streams. 8. d. Benchmarks can also be church spires, water towers or any point which can be readily picked out of the landscape. 9. c. A turkey vulture can smell a rotting mouse from 200 feet up in the air. \

10. d. While most lightning is beneath the cumulonimbus cloud, positive lightning can strike more than 10 miles away from the cloud. 11. d. 12. b. Bats usually produce one offspring a year after they reach maturity at two or three years of age. 13. c. Flickers use their long tongue covered with sticky saliva to collect ants. 14. c. Killdeer draw predators away from their nest by bluffing an injury and emitting a loud piercing call. 15. True. Females can reach nine inches and males can reach seven inches in length. 16. d. Crab spiders patiently wait on flowers until an insect lands and once caught, the toxic venom paralyzes the insect. 17. a. The only males in the hive are drones and their sole purpose is to mate with the queen. 18. True. Since marsh wrens and red-winged blackbirds live in the same habitat, they prey on each other’s eggs. 19. c. Each type of silk has a specific purpose, such as making egg cocoons, releasing draglines, wrapping prey or creating different parts of a web. 

20. b. The mourning cloak butterfly is one of the first butterflies flying around in spring, even if there is snow on the ground. 21. a. Most owls nest in February or March and that is when their calls can be heard the most at dusk and at night. 22. c. Raccoons will eat almost anything they can get their paws on from bird eggs to fish to garbage.