Wednesday, November 28, 2012

Ground Squirrels Give a Hand to Burrowing Owls

The San Diego Zoo is reporting on the initial success of a project to help restore populations of burrowing owls in San Diego county by introducing California ground squirrels to their territory.

Welcome to the neighborhood!

The small owls, along with other species, have declined in number largely due to the introduction of non-native grasses by ranchers. These grasses provide a thicker ground cover than the owls are adapted to. According to researcher Ron Swaisgood of the San Diego Zoo, it would be impossible to restore this habitat to its previous state. However, introducing California ground squirrels might help to recreate a similar habitat as the squirrels dig their burrows and open up the vegetation.

Hey, where am I?

This project is, of course, not without its challenges and setbacks. Many of the ground squirrels apparently don't like their new home and take off for surroundings more to their liking. Others become prey for hawks and coyotes. But the researchers do what they can to ease the squirrels into their new hood. They move groups of squirrels that already know each other together (the squirrels are taken from private land where they are not wanted); the squirrels spend the first week in an "acclimation chamber" getting used to the new area; then they are fed tasty treats for several months as incentive to stick around.

So far the program has had some success. At least some of the squirrels are digging burrows and setting up households. And the owls seem to be benefiting, as some have already moved into abandoned squirrel burrows. The research team is closely monitoring the squirrels after release, and hoping to learn how to better insure greater success in the future!

Prairie Dog Reminder

Just a note to anyone who stumbles across this blog: on the right-hand side of this page you will see a widget where you can click to sign my petition on Care2, asking the EPA to ban two cruel, horrible poisons that ranchers and land developers routinely use for the mass slaughter of black-tailed prairie dogs. I am asking that you sign this petition. There are more humane ways to deal with prairie dogs if they absolutely must be removed from ones property. You can read more about why I care deeply about this issue here on my previous post. I and the prairie dogs thank you for your help.

Monday, November 19, 2012

Squirrel Facts: Squirrels of the Desert

When most Americans think of squirrels, we think of the eastern gray, the familiar bushy-tailed tree squirrel of parks and suburban yards. But there are many different kinds of squirrels--over 300 species worldwide, and they live in almost every different kind of environment that we can imagine, from the tropics to the arctic. There are even squirrels that live in some of the harshest, most hot and arid deserts in the world.

Mohave Ground Squirrel, Mohave Desert, Southwestern US

Ground squirrels can be found living and thriving in two of the hottest, driest deserts of the world: the Mohave Desert of southwestern North America; and the Kalahari Desert of southern Africa. In both of these regions, daytime summer air temperatures can reach up to 114 degrees F, with surface soil temperatures as high as a blistering 140 degrees. Needless to say, animals that live in these places must evolve strategies to cope with such extreme conditions. The squirrels of these deserts have indeed developed some ingenious ways to survive.

Cape Ground Squirrels, Kalahari Desert, Southern Africa

One way that desert squirrels survive the heat is through a sort of reverse hibernation called aestivation. Just as ground squirrels and other mammals of cold arctic regions go into hibernation, some ground squirrels of the deserts will put on body fat, go into a burrow, and lower their heart, respiration, and metabolic rate, basically sleeping through some of the hottest months of the year. The Mohave ground squirrel, a rarely-seen ground squirrel of California, will aestivate from mid-summer through the fall, emerging in January or February. During the spring following a drought season, these ground squirrels might even skip mating and reproducing that year, and begin their aestivation as early as April.

Young Mohave Ground Squirrels

Squirrels of the desert also cope with the extreme heat by adjusting the times that they spend looking for food. Cape ground squirrels of the Kalahari desert will usually forage for food during the daytime during the cooler winter months. But in the summer, they will stay underground in their burrows during the hottest parts of the day, emerging to search for food only in the early morning and the late evening. These squirrels also store food in their burrows, so that they will have something to eat during those hottest periods.

When desert squirrels must forage for food in the heat of the midday sun, they can find ways to minimize their discomfort. Round-tailed ground squirrels, another species of the southwestern US, climb into bushes to forage, taking advantage of the shade and minimizing their contact with the hot sand. And the Cape ground squirrels, when they must go out into the daytime sun, use their bushy tails as "umbrellas" to give themselves some shade.

Round-Tailed Ground Squirrel, Southwestern US

It is not surprising that most or all of the squirrels of the deserts are ground squirrels, which live in burrows under the ground surface. Burrows are an extremely important part of the desert squirrels' survival strategy. For example, when measured over a period of a week, the daytime temperature outside reached over 100 degrees F and nighttime temperatures dropped as low as 23 F, but the temperature inside the burrow of the round-tailed ground squirrel stayed between 68-77 degrees F. Often when returning to the burrow after foraging in the hot sun, a squirrel will lie flat on its belly on the cool earth, or like the Mohave ground squirrel, will even dig into the ground, pushing its body through the cool soil, to help dissipate body heat and cool off.

Antelope Squirrel, Southwestern US

Desert ground squirrels have evolved several physical adaptations to cope with the hot and dry conditions in which they live. Some, like the antelope squirrel, are able to withstand higher body temperatures than most animals, even up to 110 degrees F; or, like the Townsend's ground squirrel, have a lower base body temperature, so that it can remain outside in the heat for a longer time before reaching a dangerously high temperature. Many desert ground squirrels have light-colored fur, reflecting the sun's rays, but dark skin pigmentation, which protects them from absorbing excess ultraviolet radiation.

Cape Ground Squirrel

Finally, desert-dwelling squirrels have evolved physical strategies to reduce their need for water. These adaptations include extremely efficient kidneys, reducing water loss through urination; and fewer mucus-producing cells in their lungs, reducing the amount of water lost through respiration. Because of these adaptations, many desert ground squirrels, like the antelope squirrel, can obtain most of the water that they need not through drinking but through the food that they eat.

Round-Tailed Ground Squirrel

Much of the information for this post came from the book Squirrels: The Animal Answer Guide, by Richard W. Thorington Jr. and Katie Ferrell. This book is an excellent source of information and a highly entertaining read for anyone interested in squirrels. If you are interested in this book, you can get a copy by clicking the link below.

Wednesday, November 7, 2012

Climate Change and the North American Red Squirrel

The American red squirrel, also known as the pine squirrel and the chickaree, is a medium-sized tree squirrel that inhabits much of the northern and eastern regions of North America, including most of Canada and the northeastern United States. Its diet consists largely of the seeds of conifer cones, although they also enjoy many other foods including conifer buds and needles, mushrooms, flowers, berries, and sometimes birds' eggs. Unlike the scatter-hoarding gray squirrel, the red squirrel stores food, primarily conifer cones, in a central location to provide food for the winter. The accumulated uneaten scraps from these food stores left behind by a red squirrel create a "midden" or trash pile that can measure as much as a meter in diameter.

Compared to the eastern gray squirrel, the American red squirrel is smaller but more aggressive in defending its territory. It is less likely to be seen in suburban yards and city parks, preferring wilderness areas more isolated from human activity. Also in contrast to the gray squirrel, the red squirrel will sometimes nest underground during the winter, although like other tree squirrels the red squirrel does not hibernate.

A recent study has examined the effects of global climate change on the feeding and mating habits of red squirrels over a period of several generations.

The authors of the study tagged and monitored the females of a population of approximately 325 red squirrels in the Yukon territory of Canada, from 1989-2001. During that period, the researchers kept track of the weather in the area, and monitored the feeding and reproductive habits of the squirrels. During the time of the study the mean spring temperature increased by 2 degrees Celsius. The production of the spruce cones that provide the squirrels' most important food source increased by 35 percent during the same period. And at the same time, the squirrels' breeding took place 18 days earlier by the end of the study period, advancing by about 6 days each generation.

The findings of this study seem on the surface to suggest that global warming has been beneficial to this population of squirrels. However, it is impossible to know what the long-term effects could be, both to the red squirrels and to other plant and animal species, and to the ecosystem as a whole. What seems to me most important about this research is the demonstration that climate change is having very real and demonstrable effects on the environment that has repercussions for the behavior of species. Much more long-term research is needed in this area.

Friday, November 2, 2012

Squirrel Facts: The Black Tailed Prairie Dog Needs Help

I have written about the black-tailed prairie dog before on this blog. Yesterday I created a petition on the website to try to help this species by banning the use of two horrible poisons. Although I understand that the chances of success are slim, I want to do my part to raise awareness of the cruelties that are being inflicted on these animals. I am asking that you sign the petition and help spread the word.

This large ground squirrel of the grassy prairie and plains regions of North America lives in large colonies that can number in the hundreds or even thousands. Within their "towns" prairie dogs live in extended family groups or "coteries" consisting of several related females, their first-year young, and one or two males. Members of the coterie engage in mutual grooming, greet each other with "kisses" and hugs, and cooperate in activities such as caring for young and watching for and alerting others of potential danger.

Black-tailed prairie dogs live in burrows which can be amazingly complex. Each burrow may have multiple entrances, increasing the chance for escape from predators. The tunnels, marked by entrances ringed with a mound of dirt to help keep out water, may be up to five meters deep and 30 meters long. A burrow will usually be used by several generations of prairie dogs, and when abandoned may be taken over by other animals.

Unfortunately, the black-tailed prairie dog has been unfairly demonized by cattle ranchers and land developers. Ranchers believed, incorrectly, that the prairie dogs were taking food that was needed by their herds of cattle. This belief, which persists to this day, has let to the mass extermination of prairie dogs from their range. Today, after more than a century of slaughter by shooting and poisoning, the black-tailed prairie dog occupies less than two percent of its former range. Now, in addition to ranchers, new enemies including suburban land developers and even many city and town governments are carrying out a war of extermination against this sociable, intelligent ground squirrel.

The ranchers' war against the black-tailed prairie dog is based on a myth. The fact is, prairie dogs coexisted on the plains and prairies with massive herds of bison for thousands of years before cattle ranching took over the region. Bison and cattle require a very similar diet, and the prairie dog actually provides a benefit to the growth of the grasses that they eat. Their tunneling activity churns and mixes the soil and organic matter, and helps with water retention in the soil. Overgrazing by cattle does considerably more damage to the land than the presence of prairie dogs, and the activity of the prairie dogs may actually help to repair some of the damage done by the cattle.

Prairie dogs are also a vital component of the natural plains and prairie ecosystems. Ecologists refer to the black-tailed prairie dog as a "keystone" species. This is because a large number of other species are dependent on the prairie dog. They provide food for many predators including the American badger, bobcat, coyote, snakes, weasels, bald and golden eagles, hawks, and the critically endangered black-footed ferret, which has been driven to the brink of extinction by the extermination of the black-tailed prairie dog from its range. Many other animals, including snakes and burrowing owls, use abandoned prairie dog burrows for their homes. In all, at least 140 other species benefit from the presence of prairie dogs in their ranges.

Among the most lethal weapons in the arsenal of the enemies of the prairie dog are two poisons, Rozol (chlorophacinone) and Kaput-D (diphacinone). These two products have been approved by the EPA for use in ten states, in spite of the utter cruelty that they inflict on their victims and the widespread harm that they do to the environment.

These chemicals are blood thinners. When a prairie dog or other animal eats the poison, it experiences a slow, painful decline and death by internal bleeding that may take several weeks. During that time the prairie dog becomes weak and disoriented, making it easier prey for carnivores. After death the poison will remain in the carcass. Any animals that eats the meat will also consume the poison.

Several years ago the Environmental Protection Agency considered and rejected listing the black-tailed prairie dog as a threatened species under the Endangered Species Act. It has also given approval to the use of these two cruel, dangerous poisons. I believe that the EPA is negligent in carrying out its intended mission. I hope that you will help by signing the petition and take a stand for the prairie dogs.

If you would like more information on black-tailed prairie dogs and the threats that they are facing, you can read more here for general black-tailed prairie dog info, and here for more on the effects of Rozol and Kaput-D.

Thursday, November 1, 2012

Please Help Prairie Dogs

I have just created a petition on the Care2 web site asking the EPA to ban the use of two deadly poisons, Rozol and Kaput-D, for killing prairie dogs. Currently these two loathsome products are approved for use in ten states. I plan to write a longer post on the plight of the black-tailed prairie dog tomorrow, when I am less tired. For now, I'm asking that you click on the link and sign this petition to help these awesome, intelligent and sociable ground squirrels.