WHAT'S NEW IN NATURE? 2004 Archive

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June 2004:
Our resident bats are reproducing right now! Little brown bat (Myotis lucifugus)

The little brown bat is a small mammal with a body length of 3 - 31/2" and weighing approximately 1/8 to 1/2 an ounce. The wingspan of little brown bats range from 6 - 8". Bats are the only mammals that engage in truly active flight. As their name suggests they are glossy brown above with a light buff color below. These bats can live 20 to 30 years.

The Little Brown Bat is found from Labrador west to central Alaska and south to the Appalachians in Georgia and Arkansas. Located in most states except Florida, Texas, and southern California. The little brown bat is found abundantly throughout New Hampshire.
Little brown bats are insectivorous, eating a variety of insects including some agricultural pests. They can eat 50% of their own body weight each evening. During gestation and lactation, even more insects are consumed. These nocturnal mammals use echolocation to navigate and locate prey.

Bats hear high frequency sounds emitted by their prey enabling them to distinguish contracting a muscle in the ear, these bats can block out their own sounds while still detecting prey. Little brown bats feed primarily over wetlands and other still water where insects are abundant. They use rivers, streams, and trails as travel corridors to navigate across the landscape. Bats will occasionally swoop down close to mammals to indulge on the insects that swarm around them, not to make a nest in the hair.

Little brown bats hibernate in clusters during the winter months, though little is known on hibernation locations in New Hampshire. Caves or mines are preferred but large tree cavities with favorable microclimates may be used. In order to minimize evaporative losses the humidity in these hibernation areas must be high, preferably over 90%. A constant temperature of 40 degrees F is desirable for hibernation.

Sexual maturity is reached in 6 to 9 months for females and a year for males. Breeding occurs from September to October but the female stores the sperm for fertilization in the spring. The young are born from mid-June to early July. Little brown bats generally have one offspring per year, occasionally two. The young become self-supporting within a month.

Little brown bats seek cavities for shelter, roosting and brooding. In summer females brood their young in dark, warm sites such as barns, attics, caves, hollow tree cavities and other protected areas. Little brown bat roost sites are highly variable and not well known. In temperate regions, they often use cavities along forest edges with high sun exposure.

Management of bats
• Suitable roost sites for bats can be maintained by conserving standing dead trees (snags) along riparian areas, forest edges and in regenerating stands. Maintaining snags, particularly those over 14 inches width, in mature and over-mature stands is also beneficial.
• Avoid any disturbance of bats during hibernation.
• Avoid handling bats and vaccinate dogs and cats for rabies.
• Bat houses promote public awareness of bats, although their effectiveness is uncertain. To encourage bats, place the house in an area that receives at least four hours of sun exposure and is within a quarter mile of streams or rivers. A darkened bat house will absorb more heat and be more effective in cooler regions such as New Hampshire.

Your opinion of bats may be less favorable if you find them in your living quarters.

First thing, do not use pesticides. Adult bats leave their roosts to feed every night and don't need to be coaxed out. If this is a nursery colony, wait until the young can fend for themselves. This doesn't take long -- about five weeks. Most bat pups are born in late June or early July; so by mid-August (these dates are for Indiana), even the youngsters should be weaned and well on their way to independence.

Assuming you didn't do anything to knock him down, a bat on the floor is probably sick. It should not be handled with bare hands. Contrary to folklore, bats are no more likely to carry rabies than any other woodland creature. However, taking the chance is foolish. Unlike birds, most bats find it difficult to take flight when lying on a horizontal surface; they normally get airborne by falling instead of flapping their wings. So you should be able to scoop it up in a shovel or dustpan and take it outside.

Healthy bats are very mobile and you probably aren't going to be able to catch them. The best way to get rid of them is to determine where they are getting in and out. You can usually figure this out by the guano on or below the entrance. Wait until they leave to feed, then nail or staple a screen or fine hardware cloth over the opening(s). Do not use netting -- they can get entangled in it -- and they are very good at getting around any fabric. You will be rid of most of them after the first night. If you have some stragglers, they will get very hungry very quickly. Take down the hardware cloth the following evening, let them out too, then put it back up. If the rest of your residence or outbuilding is bat-tight, that should take care of it. --National Speleological Society (promoting the study & conservation of caves) http://www.caves.org
For more information on bats visit the Bat Conservation International website – http://www.batcon.org/

May 2004:
The Fisher: New Hampshire’s Rodney Dangerfield

Historically speaking, New Hampshire’s Fisher, like Rodney Dangerfield, got no respect. Although fishers are now widespread, many of the state’s citizens would prefer to have the fisher exterminated, or nearly so. Fishers are blamed for all manner of problems. The fisher has seemingly always been a creature of mystique, mystery, and fear. Commonly—and mistakenly—called a “fisher cat,” the fisher has endured the scorn of generations. Rabbits, partridge, pheasants, turkeys, horses, and children are supposedly all vacuumed up by the fishers’ relentless marauding. This is NOT the fisher I know!

Contrary to popular belief, house cats are not a regular food item for fishers. Scientific studies show that fisher prefer to eat small prey species. Mouse-sized animals make up about a third of their diets, and a smaller proportion is snowshoe hare. Most of the fisher’s diet consists of mice, small birds, fruit, and berries, as well as deer in the form of carrion. Cat hairs were found in only one of over 1,000 stomachs examined in 1979 and 1980.

Fishers remain one of the most secretive and mysterious characters on the wildlife scene. About the size of a cat (measuring 20 to 25 inches long without the tail, and weighing about 6 to 12 pounds) a fisher has shorter legs and a longer body than a cat, so it looks more like its true relatives, the weasel, mink, and otter. Fishers appear to be all black, but the fur around their face and shoulders is lighter in color. Solitary animals, fishers can be active day or night. They tend to avoid field and open land without overhead cover, preferring forested areas, especially those with the densest canopies, like evergreens.

Fishers, along with most of New Hampshire’s other furbearers, were nearly exterminated from the state in the years before the Civil War because unregulated trapping since the mid-1600s had taken its toll. Habitat loss also contributed to the decline in the fisher population. The forested habitat preferred by the fisher was at a premium in those days, because much of the New Hampshire’s land was in agricultural use. Some measure of protection was afforded the fisher in the early 1900s, but it was not until 1934 that total protection was finally given to the few residential fisher left in the North Country. The remnant population rebounded, re-establishing themselves in the state from north to south. It’s not true that fishers were imported into the state in order to control porcupine numbers (though they are one of the few animals that prey on porcupines); rather, fisher populations came back once they were given complete protection. The fisher was again abundant enough in 1962 to declare an open season. During the early 1970s the value of fisher pelts soared, leading to another population crash in 1976. After a couple of years of closed seasons, fisher trapping re-opened in 1979 with a shortened season and restricted bag limits. The population has steadily increased since then, with trappers taking about a thousand fishers a year in the late 1990s, despite a much lower pelt value.

Based on evidence from the state’s trappers, Fishers are as abundant today in New Hampshire, especially in the southern third of the state. Fish and Game closely monitors changes in the population levels to assure there won’t be another collapse in the number of fishers in the state. We don’t want history to repeat itself, because this secretive mammal is part of what makes New Hampshire such a special and wild place to live. --Eric Orff, Wildlife Biologist

March 2004:
Bored with winter?

Why don't you build an igloo. It's a fun activity for adults and children. Mike and Carol Andrews went to an igloo building class at Yestermorrow Design Build School in Warren, VT. Bert Yankeliun, engineer from the cold Regions Research Lab showed us how. The Montshire Museum also holds classes for igloo building enthusiasts.

Building an Igloo
The following is reprinted from "The Complete Wildnerness Training Guide" written by Hugh McManners and published by Dorling Kindersley.
From Chapter Three, "Living In The Wild"
Provided temperatures remain below 32 degrees F, constructing snow shelters is relatively easy. Sheltering from the wind is the first priority, since the wind can drastically decrease the air temperature. Temperatures below 14 degrees F become increasingly unpleasant, so that it becomes necessary to construct shelters in which heat can be retained extremely well. These can range from a simple, hollowed-out heap of snow to an igloo, which can take a few hours to construct. In a long-term shelter, such as an igloo, heavy, cold air can be diverted away from the occupants by digging a cold sink to channel the air down and away from the shelter. It is important to allow for adequate ventilation in all snow shelters in order to prevent suffocation.

1. Cut blocks from dry, hard, hard snow, using a snow saw or large knife. Each block should be about 3 ft. (1m) long, 15 in. (40cm) high, and 8 in. (20cm) deep.

2. Form a circle with blocks around the hole created where you cut the blocks. Cut the circle in a spiral from the top of the last block to the ground ahead of the first block. Make sure the cut angles to the inside of the circle. This will make it easy to construct a dome.

3. Build up walls, overlapping the blocks and shaping them so that they lean inward. Cut a hole under the wall for the cold sink and entrance. Put several blocks along one wall as a sleeping platform.

4. The last block must initially be larger than the hole. Place the block on top of the igloo, then, from inside, shape and wiggle it to slot exactly into the hole.

5. Hot air from your body and stove rises and is trapped inside the dome. Cold air falls into the sink and flows away to the outside. It is essential to cut ventilation holes in the walls with an ice ax.

Finished Igloo. With warmth inside the igloo, the surface of the walls will melt and freeze over, to form a smooth, airtight ice surface. The roof over entrance tunnel prevents snow from blowing into igloo.

WARNING! It is vital to make at least one air hole in the roof to avoid suffocation. The igloo will get very warm inside with heat from your body, even if it is cold and windy outside. Without ventilation, lethal carbon dioxide will build up. Also, the use of stoves in an enclosed shelter is not recommended due to dangerous build-up of carbon monoxide.
Note: Unless the snow has been packed by the wind it is advisable to prepare the snow the day before by shoveling snow into a pile, then tamping it down with snowshoes. It is left over night to harden.

February 2004:
New Hampshire's Seven Sleepers

Seven types of mammals dodge the depths of New Hampshire's winter by snoozing it away. Bats, woodchucks, chipmunks and jumping mice go into a deep sleep, or hibernation. For these animals, life nearly ceases; they are at death's door. Yet, somehow, an alarm clock built into their bodies awakens them at just the right time. Imagine if you could hit the snooze button for four more months! Not only do these animals get to sleep as long as the average teenager, they actually have a weight loss program that works -- the winter sleepers lose between 25 and 50 percent of their weight while sleeping. Rounding out the seven sleepers, bears, raccoons and striped skunks sleep during the cold months, but not as deeply as the true hibernators. Sometimes they snooze only during the coldest, snowiest parts of the winter. New Hampshire's seven wildlife sleepers are:

Woodchucks are masters of winter sleep. By late September, when air temperatures drop into the 40s, woodchucks go into hibernation. The woodchuck's weight will drop by about half over the winter. Its heart rate plummets from 105 beats per minute to just 4, and body temperature drops from 104 degrees F to about 38.

Bats are also true hibernators. By late August or September, five species of New Hampshire bats are headed for their winter dens. These are usually caves or mines, not necessarily in this state, but possibly as far as 200 miles away. The last days of summer were spent adding about 25 percent to their body weight in order to have enough fat to last the seven months in hibernation. Bats' heartbeat slows from 210 per minute to just 8. A bat's body temperature may drop from nearly 100 degrees F to 32. Shivering prevents their body temperature from dropping below freezing.

Jumping mice, both woodland and meadow, occur across the state and, like bats and woodchucks, are true hibernators. They curl into a little ball and sleep for two or three weeks at a stretch, briefly awaken, then resume their torpor. Their body temperature hovers just above freezing. Ý Chipmunks are winter wanderers between weeks-long periods of sleep. These little creatures take the time in late fall to store a cache of winter food which they eat during waking periods over the winter. Typically, chipmunks have excavated one or two chambers in their underground burrows and have filled them with hundreds of nuts. They, too, are true hibernators, as their body temperature drops from 96 to 106 degrees F to as low as 42-45 degrees F. Their heart rate slips from 60 per minute to 20. A mild winter day with little snow and an abundance of acorns will draw chipmunks out of the den for a winter scamper.

Bears may double their weight in late fall in preparation for denning. Autumns with a lack of nuts and other foods, as we experienced in New Hampshire in 2003, can send some bears into their dens as early as September. During falls with an abundance of nuts, especially beechnuts or acorns, bears often will stay active into December. Bears usually build a den on top of the ground or under a blow-down or brush pile. Their winter sleep is not as deep as that of the true hibernators, as bears remain alert and can run away or defend themselves if disturbed. Their body temperature drops only about 10 degrees, from 100 degrees F to 90. Respiration drops more significantly, from about 40 to 8-10 breaths a minute. Unlike chipmunks, bears do not eat or drink or even relieve themselves during the 5-6 months of denning. Yet adult female bears give birth to two or three cubs in January about every other year. They are able to nurse the cubs and care for them during the coldest of months by relying on body fat stored from the previous fall.

Racoons and striped skunks are the last of the winter sleepers. Unlike the true hibernators, these animals may sleep only during the coldest temperatures and the deepest snows, but remain active periodically throughout the year. There is no dramatic reduction in their body temperatures, heart rate or respiration. Life goes on, just at a slower pace. Just like us humans! To conserve energy, both raccoons and skunks congregate in communal dens. Often, it will be the mother and her young from the summer who will den together, but sometimes as many as 12 to 20 raccoons may den together. Skunks enjoy mixed company of other skunks, as well; there can be 20 or more in a den, but usually no more than 10. Skunks, especially females, prefer to make their winter dens under or in buildings. Have you noticed a telltale odor of skunk this winter? If you have, get ready for the blast of reality when skunk-breeding season rolls around in January! Male skunks may travel over two miles a night in search of that den full of vivacious babes. Squabbling males or reluctant females may cause a stir that will include some spraying. Keep that clothespin handy! The denned skunks tend to have two or three brief active periods each day, each lasting less than 10 minutes. Skunks have a slight depression in body temperature and lose between 40 and 58 percent of their body weight.

New Hampshire's seven sleepers are all snuggled into their dens for a long winter's nap. Wouldn't it be nice to sleep through that next big snowstorm, or, better yet, that ice storm when the power is out? Plus, great news - "you snooze, you lose." If Christmas dinner, ribbon candy and holiday parties have you putting on a few extra pounds, remember, the solution is only a nap away. --Eric Orff, Wildlife Biologist

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