June 19, 2007, 5:10 AM CT

Gannet population under threat from global warming

Scientists at the University of Leeds have warned that global warming is a major threat to the gannet, a species known for its stable populations and constant breeding success.

In a paper published in Marine Ecology Progress Series, Dr Keith Hamer of the University's Faculty of Biological Sciences reports that diminishing fish stocks around gannets' natural habitats - caused partly by an increase in sea temperature - are forcing birds to search further afield in search of food for their young.

"Usually, one parent will stay with a chick while the other goes out hunting, says Dr Hamer. "But if left for long enough, it will eventually leave the nest itself to find food. This leaves the chick alone and vulnerable to attack - mainly from other gannets seeking prime nesting space, which is fiercely contested within colonies".

Two thirds of the world's gannets nest in the UK, with the largest northern gannet colony found in the Scottish islands of St Kilda. Dr Hamer's research group has been studying birds nesting at Bass Rock off the Northumbrian coast, using satellite transmitters attached to the birds, to gather information about their movements.

"Gannets have been forced to travel as far as the Norwegian coast to find food - a round trip of over 1000km," said Dr Hamer. "They compensate by flying faster to make sure they don't leave their nests for too long, but our research shows they've hit their limit. They just physically can't increase their speed any further"......... Posted by: Kelly      Read more         Source

June 15, 2007, 12:21 AM CT

Warning from Asian bees

Four swarms of Asian bees found in Cairns have been cleared of carrying the dreaded Varroa destructor mite but the intruders themselves could pose the beginning of a serious threat to Australian honey bee populations.

Asian bees are known to have found their way into Australian ports at least half a dozen times in the last decade.

This time it's a Javanese strain of the bee and because the latest incursion had lain undiscovered for at least three months, it is unknown how a number of more swarms might exist and how far afield they may have flown.

Within a one kilometre radius from the first colony, disturbed in the mast of a yacht undergoing repairs after two years docked at a wharf in Cairns, three more swarms were found and the search widened.

Already operating under marginal circumstances, a number of of Australia's beekeepers can only afford a momentary sigh of relief.

Asian bees (Apis cerana) are capable of carrying two types of Varroa mite - destructor and jacobsoni; the latter would not threaten the health of local bee populations but destructor has wiped out commercial hives and feral populations the world over and Australia is the last remaining major beekeeping country free of it.

Asian bees remain feral, cannot be hived commercially and will attack Australian bees and rob their hives. In comparison to the home breed, Apis mellifera, the intruders are nowhere near the same league in the volume of honey they produce......... Posted by: Kelly      Read more         Source

June 15, 2007, 11:21 AM CT

Fruit Bats Are Not As Blind As You Think

The mammalian order bats (Chiroptera) has two suborders, microbats (Microchiroptera) and fruit bats or flying foxes (Megachiroptera). In contrast to microbats, fruit bats (Fig. 1) do not echolocate. They have large eyes and pronounced visual centres in the brain. Fruit bats need a good sense of vision, because when they forage at night for nectar and fruit, they orient by vision and the sense of smell. During the flights to the foraging grounds at dusk and the return to the daytime roost at dawn, the animals navigate solely by vision. On moonless nights, fruit bats cannot fly and stay hungry. Visual navigation at twilight and sometimes also during the daytime did not fit the older view that fruit bats only possess rods, the photoreceptors for night vision. This prompted Brigitte Müller and Leo Peichl of the Max Planck Institute for Brain Research in Frankfurt/Main and Steven Goodman from The Field Museum for Natural History in Chicago to study the photoreceptors of fruit bats with modern histological methods.

To identify the different photoreceptor types, the scientists stained the retinas of various fruit bat species with visual pigment-specific antibodies. As expected, all megabats had high densities of rod photoreceptors, the prerequisite for nocturnal visual orientation. In addition, all species could be shown to possess cone photoreceptors, comprising about 0.5 percent of the photoreceptors. "This share of cones appears small, but from studies of other night-active mammals we know that it allows daylight vision", says lead author Brigitte Müller. For example, cats and dogs only have two to four percent cones, and even the diurnal human retina contains an average of only five percent cones. "The retina of flying foxes is no 'evolutionary quirk', but conforms to the general mammalian blueprint that comprises rods and cones", says Müller......... Posted by: Kelly      Read more         Source

June 13, 2007, 9:56 AM CT

Lizard Moms Dress Their Children

Mothers know best when it comes to dressing their children, at least among side-blotched lizards, a common species in the western United States. Scientists at the University of California, Santa Cruz, have observed that female side-blotched lizards are able to induce different color patterns in their offspring in response to social cues, "dressing" their progeny in patterns they will wear for the rest of their lives. The mother's influence gives her progeny the patterns most likely to ensure success under the conditions they will encounter as adults.

In a paper published June 10 in the online early edition of the journal Ecology Letters (and in a later print issue), the scientists reported that female side-blotched lizards give an extra dose of the hormone estradiol to their eggs in certain social circumstances. The extra hormone affects the back patterns of lizards that hatch from those eggs, creating either lengthwise stripes down their backs or bars stretching from side to side. Whether they get stripes or bars depends on the genes for other traits.

"This is the first example in which exposure to the mother's hormones changes such a fundamental aspect of appearance. Even more exciting is that the mother has different patterns at her disposal, so she can ensure a good match between back patterns and other traits that her offspring possess," said Lesley Lancaster, a UCSC graduate student and first author of the paper......... Posted by: Kelly      Read more         Source

June 13, 2007, 9:46 AM CT

Massive Migration Revealed

Seen thundering across the landscape during an aerial survey, more than 1.3 million white-eared kob, tiang (African antelope), and mongalla gazelle are thriving in Southern Sudan, despite all odds. An estimated 8,000 elephants, concentrated mainly in the Sudd, the largest freshwater wetland in Africa, have also been observed. Researchers are astonished at the latest news: Based on experiences in other war-torn regions such as Mozambique and Angola, they believed wildlife had vanished from this area.

"I have never seen wildlife in such numbers, not even when flying over the mass migrations of the Serengeti," said J. Michael Fay, who conducted the surveys. Fay is a field scientist with the Wildlife Conservation Society (WCS) and a National Geographic Explorer-in-Residence. "This could represent the biggest migration of large mammals on Earth".

Paul Elkan, director of the WCS Southern Sudan Country Program, and Malik Marjan, a Southern Sudanese Ph.D. candidate from the University of Massachusetts Amherst, worked alongside Fay on the project. The team collaborated with the Ministry of the Environment, Wildlife Conservation, and Tourism of the Government of Southern Sudan (GoSS). USAID/Sudan and the U.S. Fish & Wildlife Service provided additional funding.

WCS last surveyed southern Sudan in 1982, one year before civil war broke out. During the decades-long war with northern Sudan, political obstacles and conflict precluded further scientific studies there. As part of a 2005 peace agreement, Southern Sudan formed an autonomous region and will hold a referendum on independence in 2011......... Posted by: Kelly      Read more         Source

June 13, 2007, 8:38 AM CT

Rove beetles act as warning signs

New research from the University of Alberta and the Canadian Forest Service has revealed the humble rove beetle may actually have a lot to tell us about the effects of harvesting on forests species. Rove beetles can be used as indicators of clear-cut harvesting and regeneration practices and can be used as an example as to how species react to harvesting. It has been observed that after an area of forest was harvested, the a number of forest species, including rove beetles, decreased dramatically. As the forest regenerated, it never fully replicated the full characteristics of the older forest it replaced.

As insects are the most abundant animal species in forests, they have enormous potential as indicators of habitat change and recovery and are increasingly being used in conservation studies.

We felt beetles were excellent candidates for this study because they are abundant and diverse, easily sampled, inhabit a variety of niches and are very sensitive to habitat change, said John Spence, professor of Renewable Resources at the University of Alberta.

A total of 13, 978 rove beetles were collected and 98 species were identified during this study.

Once the forest was harvested the overall abundance of rove beetles declined while the diversity of species increased. Also most mature forest-dwelling species became much less abundant or disappeared completely immediately after harvest. Even the low amount of mature forest beetles that survived the initial harvest would eventually die out or migrate elsewhere within a few years of harvest......... Posted by: Kelly      Read more         Source

June 13, 2007, 8:17 AM CT

Preserving Arctic Whale

Research on one of the oldest-living mammals - the bowhead whale - has helped preserve a primary food source for Eskimos in the far reaches of Alaska, and also may provide a useful tool for studying genetic variation in other migratory animals.

The bowhead whale, devastated in the 19th and early 20th centuries by commercial whaling fleets, has been a food staple for Eskimos and other indigenous arctic peoples dating to prehistoric times. Due in part to research done by Purdue University professor John Bickham, the International Whaling Commission ruled last week to allow Eskimos to harvest 56 whales per year, the same quota that had been in place but had expired.

"Eskimos have been whaling for more than 2,000 years and have never endangered the bowhead whale," said Bickham, the professor of forestry and natural resources who presented data from a study he co-authored at the scientific meeting of the commission in May.

Bickham said the bowhead's population has recently been increasing by 3 percent a year, even while being harvested by subsistence hunters. The bowhead, he said, which can be 50 feet long and weigh 50 tons, should be able to increase its 11,000 population under the quota.

At the commission meeting, which ended May 31, the 76 member nations voted to renew the subsistence hunt quota for the next five years. Members of the Alaska Eskimo Whaling Commission, worried the quota might not be renewed, celebrated the news......... Posted by: Kelly      Read more         Source

June 13, 2007, 7:30 AM CT

Divorce Among Galapagos Seabirds

Being a devoted husband and father is not enough to keep an avian marriage together for the Nazca booby, a long-lived seabird found in the Galapagos Islands off the coast of Ecuador.

A number of Nazca booby females switch mates after successfully raising a chick, as per a Wake Forest University study scheduled for publication in the journal Proceedings of the Royal Society B: Biological Sciences June 13.

This is surprising because there is an advantage to staying together, said Terri Maness, a doctoral student who co-authored the study with David J. Anderson, professor of biology at Wake Forest. The chance of successfully breeding probably improves as the pairs of birds get older and are together longer, as has been found in other birds.

But, often the female seeks a divorce after a few breeding seasons. Since males significantly outnumber females in the colony studied, there are plenty of bachelors available if the female has a wandering eye.

Our study population has 50 percent more males than females, creating the opportunity for females to trade a current mate, which may be worn-out from recent breeding effort, for a refreshed non-breeding male, Maness said.

It takes a lot of energy to raise a chick and the responsibility is shared by both males and females. They raise one chick at a time. Parents incubate the egg for 43 days. Then, it takes another 100 to 120 days of parental care until the baby bird can fly. The parents will commonly continue to provide some meals to the fledgling......... Posted by: Kelly      Read more         Source

June 11, 2007, 4:13 PM CT

Climate Change, Deforestation And Global Bird Diversity

Global warming and the destruction of natural habitats will lead to significant declines and extinctions in the world's 8,750 terrestrial bird species over the next century, as per a research studyconducted by biologists at the University of California, San Diego and Princeton University.

Their study, the first global assessment of how climate change and habitat destruction may interact to impact the distribution of a large group of vertebrates over the next century, appears in the June 5 issue of the journal PLoS Biology.

The researchers warn in their study that, even under the most optimistic scenarios of controlling climate change and protecting habitats, at least 400 bird species are projected to become imperiled by the year 2050 due to reductions in their geographic ranges of greater than 50 percent. All estimates in the study are based on the assumption that birds will not dramatically shift their geographic ranges in response to a changing climate.

"We found in our study that under certain assumptions by the year 2100, 950 to 1,800 bird species may be imperiled or even driven to extinction by climate change and habitat destruction," says Walter Jetz, an assistant professor of biological sciences at UCSD and the lead author of the study. "Most of these species are currently not recognized as imperiled"......... Posted by: Kelly      Read more         Source

June 10, 2007, 8:59 PM CT

History of Caribbean Frog Population

Nearly all of the 162 land-breeding frog species on Caribbean islands, including the coqui frogs of Puerto Rico, originated from a single frog species that arrived on a sea voyage from South America. They came 30 to 50 million years ago, as per DNA-sequence analyses by researchers at Penn State.

Similarly, the researchers observed that the Central American relatives of these Caribbean amphibians also arose from a single species that arrived by raft from South America.

"This discovery is surprising because no prior theories of how the frogs arrived had predicted a single origin for Caribbean terrestrial frogs, and because groups of close relatives rarely dominate the fauna of an entire continent or major geographic region," said Blair Hedges of Penn State, an evolutionary biologist who directed the research. "Because connections among continents have allowed land-dwelling animals to disperse freely over millions of years, the fauna of any one continent is commonly a composite of a number of types of animals".

The results would be reported in the June 12, 2007 issue of the Proceedings of the National Academy of Sciences and posted in the journal's online early edition this week.

The field work for the study mandatory nearly three decades to complete because a number of of the species are restricted to remote and isolated mountain tops or other inaccessible areas. Some species included in the study are thought to beextinct because of habitat degradation and other causes......... Posted by: Kelly      Read more         Source