Thursday, February 26, 2015

Baby It's Cold Outside!

Since the cold icy weather hit North Texas Sunday evening we have been indoors, staying warm, but have been thinking, as we watch birds at the feeders, what about the wildlife in our area?
Here are some of nature’s strategies for winter, from “Science Made Simple”:
Some animals migrate while others remain and stay active in the winter. They must adapt to the changing weather. Many make changes in their behavior or bodies. To keep warm, animals may grow new, thicker fur in the fall.
Food is hard to find in the winter. Some animals, like squirrels, mice and beavers, gather extra food in the fall and store it to eat later. Some, like rabbits and deer, spend winter looking for moss, twigs, bark and leaves to eat. Other animals eat different kinds of food as the seasons change. The red fox eats fruit and insects in the spring, summer and fall. In the winter, it cannot find these things, so instead it eats small rodents.
Animals may find winter shelter in holes in trees or logs, under rocks or leaves, or underground. Some mice even build tunnels through the snow. To try to stay warm, animals like squirrels and mice may huddle close together.
Cold-blooded animals like fish, frogs, snakes and turtles have no way to keep warm during the winter. Snakes and many other reptiles find shelter in holes or burrows, and spend the winter inactive, or dormant. This is similar to hibernation.
Water makes a good shelter for many animals. When the weather gets cold, they move to the bottom of lakes and ponds. There, frogs, turtles and many fish hide under rocks, logs or fallen leaves. They may even bury themselves in the mud. They become dormant. Cold water holds more oxygen than warm water, and the frogs and turtles can breath by absorbing it through their skin.
Insects look for winter shelter in holes in the ground, under the bark of trees, deep inside rotting logs or in any small crack they can find. One of the most interesting places is in a gall. A gall is a swelling on a plant. It is caused by certain insects, fungi or bacteria. They make a chemical that affects the plant's growth in a small area, forming a lump. The gall becomes its maker's home and food source.
Every type of insect has its own life cycle, which is the way it grows and changes. Different insects spend the winter in different stages of their lives. Many insects spend the winter dormant, or in "diapause." Diapause is like hibernation. It is a time when growth and development stop. The insect's heartbeat, breathing and temperature drop. Some insects spend the winter as worm-like larvae. Others spend the winter as pupae. (This is a time when insects change from one form to another.) Other insects die after laying eggs in the fall. The eggs hatch into new insects in the spring and everything begins all over again.

On the website for Michigan State University Extension service, we found some additional information on winter adaptations:
  • Bergmann's Rule states that northern species of a particular genus or similar class of birds or mammals tend to be larger in size, although this is not always true.  Larger body size means a higher body mass-to-surface area ratio.  It's easier to retain heat.  Polar bears are larger than tropical bears.  White-tailed deer in Michigan dress out at higher weights than their counterparts in Texas or Florida.  
  • Body appendages tend to get smaller in the north, as a heat conservation measure.  Snowshoe hares have smaller ears that cottontail rabbits.   Mammalian legs and snouts are frequently shorter and stouter.
  • Specialized fat, called brown fat, is produced during the food-rich seasons and expended during cold seasons.  This is also the kind of fat that most hibernators use for arousal and many migrators use for fuel.
  • Various "heat exchange" mechanisms can be found in animal circulatory systems that reduce heat loss to body extremities.
  • Certain fish and herptiles produce chemicals within and between cell walls that can lower their freezing temperature a few degrees.  In sheltered environmental niches, these few degrees can mean the difference between life and death.
  • Some mammals, such as flying squirrels and small rodents, will occupy collective dens to conserve body heat, even though some species are non-colonial during the warm season.  This is part of the reason that some species of snakes will do the same thing.
  • Food preferences change with the season.  Some browsers, such as white-tailed deer, have changes in digestive enzymes to cope with the different food sources.  This is one of the reasons why biologists argue against winter deer feeding.  If not done correctly, a deer can starve to death with a belly full of corn.
  • Aquatic mammals, such as otter and mink, grow thick layers of insulating fat and have specialized fur.  Similarly, ducks, geese, and swans have feathers and oil glands that keep water away from the skin.  Some have efficient circulatory heat exchangers between the body and the feet.  It's usually not the cold that causes waterfowl to migrate.  It's more a matter of food shortages. 
  • Birds and mammals undergo seasonal changes in feathers and pelage.  Trappers know that winter pelts are the highest quality because they are thicker and have different kinds of hair.
  • Muskrats and beaver construct shelters, partly for protection from severe weather.  A number of animals dig burrows, such as groundhogs, foxes, chipmunks, and moles. 
  • Many species of birds can adjust their internal body temperature downward to reduce the temperature gradient with environmental temperatures, thus reducing heat loss.  They also tend to shiver a lot to maintain body temperatures. 

From the website, Earth Gauge we learn that:

Prior to the actual onset of winter, animals that resist winter stresses have physiological responsesthat are cued in by the reduced daylight hours. Less daylight triggers a response that isregistered in the “master control” gland (hypothalamus) in the brain. The hypothalamus thensecretes hormones that activate other systems throughout the animal’s body. Animals react invarious ways. Moose, elk and deer begin to rut. The interval between the mating season and givingbirth ensures the young will be born in the spring when food is abundant. Another reactionto shorter days is the urge to eat more thus building up layers of fat that will help animals make itthrough winter. Beavers and red squirrels cache extra food. Animals that remain active all winterwill grow a thicker coat of fur. Deer, elk and moose have winter coats comprised of hollowhairs that trap air for better insulation. Other animals develop thick undercoats.

Even though we may be winter-ready, we are still eager for Spring! 

Thursday, February 19, 2015

The Martins Are Coming!

All the way from South America! Yes, our largest common North American swallow, according to Cornell Lab of Ornithology, the Purple Martins should be arriving in North Texas neighborhoods any day now, for the summer breeding season. You can follow their migration progress on the Purple Martin Conservation Association site’s 2015 Scout Arrival Page.

For the fourth year, the welcome mat is out at Hagerman National Wildlife Refuge for Purple Martins, at the big Martin house just outside the Visitor Center at the Refuge, purchased by the Friends of Hagerman and installed in 2012 by Refuge staff and volunteers.  The staff reported  7 confirmed nests in the Martin house in 2014.

Some “Cool Facts” about Purple Martins, from Cornell Lab of Ornithology include:

     Native Americans hung up empty gourds for the Purple Martin before Europeans arrived in North America. Purple Martins in eastern North America now nest almost exclusively in birdhouses, but those in the West use mostly natural cavities.
· European Starlings and House Sparrows often push Purple Martins out of local areas by taking over all of the nest sites, including houses that people put up specifically for the martins.
· Purple Martins roost together by the thousands in late summer, as soon as the chicks leave the nest. They form such dense gatherings that you can easily see them on weather radar. It’s particularly noticeable in the early morning as the birds leave their roosts for the day, and looks like an expanding donut on the radar map.
· Despite the term "scout" used for the first returning Purple Martins, the first arriving individuals are not checking out the area to make sure it is safe for the rest of the group. They are the older martins returning to areas where they nested before. Martins returning north to breed for their first time come back several weeks later. The earlier return of older individuals is a common occurrence in species of migratory birds.
· The Purple Martin not only gets all its food in flight, it gets all its water that way too. It skims the surface of a pond and scoops up the water with its lower bill.

The Cornell Lab of Ornithology Macauley Library offers a variety of recorded songs and calls of birds; hear a sample song of the Purple Martin: In addition, the library offers videos; here is one selected for the demonstration of the Purple Martins’ flight, described as a mixture of flapping and gliding:

Another resource for those who would like to host a Martin colony is The Purple Martin Society of North America, which, with a wealth of information on Martins and Martin houses, is “dedicated to Purple Martin landlords.

Finally, are Purple Martins “skeeter eaters”? Here is the definitive answer, from the Purple Martin Conservation Association:

"Martins, like all swallows, are aerial insectivores. They eat only flying insects, which they catch in flight. Their diet is diverse, including dragonflies, damselflies, flies, midges, mayflies, stinkbugs, leafhoppers, Japanese beetles, June bugs, butterflies, moths, grasshoppers, cicadas, bees, wasps, flying ants, and ballooning spiders. Martins are not, however, prodigious consumers of mosquitoes as is so often claimed by companies that manufacture martin housing. An intensive 7-year diet study conducted at PMCA headquarters in Edinboro, PA, failed to find a single mosquito among the 500 diet samples collected from parent martins bringing beakfuls of insects to their young. The samples were collected from martins during all hours of the day, all season long, and in numerous habitats, including mosquito-infested ones. Purple Martins and freshwater mosquitoes rarely ever cross paths. Martins are daytime feeders, and feed high in the sky; mosquitoes, on the other hand, stay low in damp places during daylight hours, or only come out at night. Since Purple Martins feed only on flying insects, they are extremely vulnerable to starvation during extended periods of cool and/or rainy weather.”

This post was originally published Feb. 20, 2014 and has been updated.

Thursday, February 12, 2015

A Fish Story

A recent headline proclaimed, “North Texas woman reels in record fish at Lake Texoma.” The fish, a striped bass caught in Oklahoma waters of the lake, weighed 27 pounds. Not to brag, but they are even bigger on the Texas side though, with record catches of over 30 pounds for the same species.

According to Texas Parks and Wildlife,
“Free-flowing current in the Red River makes Texoma one of the few lakes in Texas with a self-sustaining population of striped bass, and one of only eight inland freshwater reservoirs worldwide where this species has spawned. A cousin of the white bass, striped bass were first stocked in Lake Texoma by the Oklahoma Department of Wildlife Conservation in 1965. They began spawning in 1974.”

Lake Texoma now provides habitat for at least 70 species of fish, several of which were introduced by the Oklahoma Department of Wildlife Conservation and TPWD. Since the lake, formed in the 1940’s, is now entering its 8th decade, what changes have occurred over the years as far as the fish, the habit and the lake ecosystem; what have been the effects of cyclical drought and flooding? Hear Dr. Patton, Professor of Biology at Southeastern Oklahoma State University, speak on this topic for Second Saturday at Hagerman National Wildlife Refuge on February 14.

Dr. Patton has been a professor at Southeastern Oklahoma State University since 1998, where he teaches numerous classes in Fisheries and Wildlife Science. His recent related research has included fish-habitat relations in rivers of Oklahoma and Texas, sedimentation issues in Lake Texoma and freshwater turtle ecology and conservation in Oklahoma.

Second Saturday sessions are held from 10 – 11:30 am, in the Visitor Center at Hagerman National Wildlife Refuge, and are free and open to the public. The Refuge,  established 69 years ago this month, is located at 6465 Refuge Road, Sherman. For more information, call 903 786 2826 or see

Thursday, February 5, 2015

Host with the Most

While the ButterflyGarden at Hagerman National Wildlife Refuge remains dormant, there is a butterfly nursery out there just waiting for spring.  These are plants that will feed, or host butterfly and moth caterpillars once eggs begin to hatch.

According to Gardens with Wings,
If you keep an eye out you’ll see the female as she flits around the plant, gently laying her next brood’s eggs, sometimes on the top of leaves but usually on the bottom, hidden from predators.  Then, in 10 to 14 days, the tiny larvae, less than an eighth inch long, emerge and begin eating the plant. It’s a fascinating process as they munch away, growing larger every day. Equally fascinating is watching the caterpillar leave the plant to form a chrysalis.    
Because tiny caterpillars cannot travel far to find their own food, the female butterfly locates and lays her eggs on only the type of plant that the caterpillar can use as food. Most species of caterpillars are particular about the type of plants they can eat. If the egg was not placed on the correct plant, the caterpillar hatching from that egg will not survive.

So what is on the menu?  

Click here for a list of common garden plants that host caterpillars in North Texas, from the North American Butterfly Association. (Scroll past Nectar Plants to Host Plants)
Here are just a few of the “caterpillar nurseries” that have been planted or are on order for spring planting in the garden at the Refuge, and the species they will host:
  • Milk Weed - Asclepias tuberosa and Asclepias viridis –Monarch and Queen
  • Texas Redbud, Yaupon Holly  – Henry’s Elfin
  • Carolina Buckthorn – American Snout
  • Bigelow Oak – Horace’s Duskywing, Hairstreak
  • Inland Sea Oats – Bell’s Roadside Skipper
  • Downy Forestiera -  Hairstreaks
  • Passionvine – Gulf Fritillary
When you see some raggedy chewed up leaves on these host plants, you will know new butterflies will soon appear!

Monarch Caterpillar, by Brenda Loveless