Just as differences in song can be used to distinguish one bird species from another, the pips and squeaks bats use to find prey can be used to identify different species of bat. Now, for the first time, ecologists have developed a Europe-wide tool capable of identifying bats from their echolocation calls.
The new free online tool – iBatsID – will be a major boost to conserving bats, whose numbers have declined significantly across Europe over the past 50 years. Details are published today in the British Ecological Society‘s Journal of Applied Ecology.
Working with an international team of ecologists, lead author and PhD student Charlotte Walters from the Zoological Society of London (ZSL) selected 1,350 calls of 34 different European bat species from EchoBank, a global echolocation library of more than 200,000 bat calls.
The calls were then analysed to find out which characteristics were most useful in distinguishing different bat species. According to Walters: “Lots of different measurements can be taken from an echolocation call, such as its maximum and minimum frequency, how quickly the frequency changes during the call, and how long the call lasts, but we didn’t know which of these measurements are most useful for telling different species’ calls apart.”
The 12 most useful call parameters were then used to train artificial neural networks to produce the new identification tool, iBatsID, which can identify 34 different bat species across the whole of Europe. Most species can be identified correctly more than 80% of the time, although accuracy varies because some species are much harder to identify than others. Continue reading →
TULANE (US) — The full impact of the 2010 Deepwater Horizon oil spill may still reveal itself as bird migration spreads the disaster far from the Gulf Coast.
The largest-ever accidental release of oil into marine waters could impact earth’s ecosystems for years to come—and not just along the 650 miles of the northern Gulf of Mexico coastline directly affected by the spill.
“More than one million migratory shorebirds representing 28 species were potentially exposed to Deepwater Horizon oil during their 2010-2011 nonbreeding season,” says Caz Taylor, assistant professor and a population ecologist at Tulane University.
“Although only 8.6 percent of the shorebirds trapped from fall 2010 to spring 2011 showed visible signs of oiling, nonlethal effects and degradation of habitat can affect populations in ways that carry over into subsequent seasons.” Continue reading →
PHILADELPHIA — Establishing protection over a swath of land seems like a good way to conserve its species and its ecosystems. But in a new study, University of Pennsylvania biologist Daniel Janzen joins more than 200 colleagues to report that protected areas are still vulnerable to damaging encroachment, and many are suffering from biodiversity loss.
“If you put a boundary around a piece of land and install some bored park guards and that’s all you do, the park will eventually die,” said Janzen, DiMaura Professor of Conservation Biology in Penn’s Department of Biology. “It’s death from a thousand cuts.”
The international team of researchers, led by William Laurance of Australia’s James Cook University, conducted 262 interviews of field biologists and environmental scientists who had extensive experience working in tropical forest reserves. In all, the interviews incorporated results from 60 protected areas in 36 countries. Continue reading →
A new study by York University researchers finds that songbirds follow a strict annual schedule when migrating to their breeding grounds – with some birds departing on precisely the same date each year.
The study, published in the journal PLoS ONE, is the first to track the migration routes and timing of individual songbirds over multiple years. Researchers outfitted wood thrushes with tiny geolocator “backpacks”, recording data on their movements.
Spring departure dates of birds heading from the tropics to North American breeding grounds were surprisingly consistent, with a mean difference of only three days from year to year, the study reports. Fall migration, however, was far less predictable. Males on average flew faster than females, and first-timers lagged behind those with more than one journey under their wings.
The geolocators, which are smaller than a dime, are mounted on birds’ backs with thin straps looped around their legs. The devices measure light, allowing researchers to estimate latitude and longitude by recording sunrise and sunset times.
“It’s quite surprising that the schedules of these birds are so consistent across the entire route, with some of them departing the tropics and arriving at breeding sites in North America on the same day in different years,” says study author Kevin Fraser, a postdoctoral Fellow in York’s Department of Biology, Faculty of Science & Engineering. “Much like airplanes, there are many factors that can influence birds’ flight schedules, such as weather at departure and expected conditions at the other end of the journey. Amazingly, these small songbirds are highly consistent in their timing between years.”
Interestingly, while their departure times are precise, songbirds’ migratory routes can vary widely. “Migratory routes sometimes differed by several hundred kilometres between years, which may reflect a fine-tuning of migration in response to wind and weather conditions en route, such as during large open-water crossings like the Gulf of Mexico,” says Fraser.
As for arrival times, birds need to be early to lay their claim to prime breeding grounds – but not too early.
“There is intense pressure for birds to get back to breeding grounds early to secure good territories, nest sites and, of course, mating opportunities. The early birds tend to do better and raise more young. However, cool weather in early spring can reduce food availability and even survival of early birds,” Fraser says. He cautions that songbirds’ consistent timing may come at a cost.
“The concern is that birds may not be able to flexibly adjust their schedules to meet new conditions with climate change,” says Fraser. “This is a topic we’re pursuing in current research.”
The birds Fraser tracked were tagged in Pennsylvania and Costa Rica, at field research sites of his supervisor, York University Professor Bridget Stutchbury, who has studied the behavioural ecology of birds for decades. Her 2007 book, Silence of the Songbirds, details the threat to the species posed by climate change and habitat destruction.
“Numbers [of wood thrush] have plummeted in Canada by over 50 percent since the 1960s. When we lose the wood thrush, and other songbirds, we lose an integral part of the forest itself,” Stutchbury says.
The research was supported by the Natural Sciences and Engineering Research Council of Canada (NSERC), National Geographic Society, U.S. Fish & Wildlife Service Neotropical Migratory Bird Grant, Kenneth M. Molson Foundation, Schad Foundation and proceeds from Silence of the Songbirds.
The study, “Repeat tracking of individual songbirds reveals consistent migration timing but flexibility in route”, is co-authored by Stutchbury, along with Calandra Stanley, Maggie MacPherson and Emily McKinnon, graduate students in York’s Department of Biology, Faculty of Science & Engineering.
SALT LAKE CITY (AP) — A baby golden eagle is recovering at a wildlife rehabilitation facility after officials say it miraculously survived a Utah wildfire last month.
Kent Keller told The Salt Lake Tribune (http://bit.ly/NKy8WO ) he feared the worst when he returned to the nest site west of Utah Lake to retrieve a leg band he had attached to the male eaglet June 1.
But the veteran Utah Division of Wildlife Resources volunteer found the burned bird alive on June 28 behind a charred tree, about 25 feet below the nest that was burned to a crisp in the 5,500-acre Dump Fire near Saratoga Springs.
“I thought there was no chance he would be alive. I was stunned when I saw him standing there,” Keller said. “I thought maybe I could rebuild the nest a little bit, but I took a good look at him and realized that was not going to happen.”
The 70-day-old eaglet had suffered burns on his talons, beak, head and wings. His flight feathers were melted down to within an inch or two of his wing and tail. He’s very underweight at just over five pounds.
Keller realized the eagle would not fly for at least a year and that the parents eventually would stop providing food. Not a stick from the nest was left after the fire sparked by target shooters swept through
“I’ve seen nests burn before, but this is the first year I have seen one burn with young in it,” he told the Tribune. “They are usually long gone and flying when fire season starts.”
After permission was secured from state and federal wildlife agencies, the Wildlife Rehabilitation Center of Northern Utah in Ogden assumed care of the eaglet this week.
“I wasn’t sure he was going to make it,” said DaLyn Erickson, executive director of the center. “He kind of had that look like he may have given up.”
But the eagle named Phoenix has since taken to eating beef heart and venison. He’s treated several times a day for his burns and seems to be gaining strength.
“He looks good now,” said Amber Hansen, a member of the center’s board of directors. “But we think if he had been there (at the nest site) another day, he probably would not have survived.”
What seems to have saved his life during the fire was the insulation offered by his down feathers and once-thick body, according to the wildlife rehabilitation center.
Officials hope the bird can be released back into the wild next year, but say it’s too early to tell about its future. Volunteers will work to keep him as wild as possible.
“It depends on how much follicle damage there is to his wings,” Hansen said. “If they are not too burned, he should be able to molt into new feathers next year and hopefully be able to fly.”
Did you think humans invented inebriation? Guess again!
Frugivores (animals that eat fruit) and nectarivores (animals that eat nectar) are limited to food sources that last a relatively short time before they ripen, then ferment, then completely rot. So you would think that a fruit-eating animal would be much more successful at feeding itself if it could eat foods in various stages of fermentation, right? Not only would the ability to eat fermented fruits increase food abundance, but alcohol also has high caloric content (ehem: beer bellies), and makes the food easier to find by that distinctive alchy-smell. So rock on, little frugivores! It’s all good!
Or is it? Imagine you’re drunk: kinda happy, stumbling occasionally, saying things you’ll likely regret in the morning, and getting lost on the way to the bathroom. Now imagine you’re being chased by a mountain lion. Crikey! You were so busy getting blitzed on fermented fruit, you forgot that you are a prey animal… and it’s a dangerous world out there!
If frugivores, such as fruit-eating bats, consumed a lot of fermented fruit, you would think they would be drunk all the time and would fly wonky and get lost and generally be less likely to survive… unless they had developed an ability to tolerate alcohol. Dara Orbach, Nina Veselka, Louis Lazure and Brock Fenton at the University of Western Ontario and Yvonne Dzal at the University of Regina decided to test the ability of several fruit-eating bats to hold their liquor. The researchers went to Belize and caught bats from six different fruit-eating species. They fed them either sugar-water or sugar-water with 1.5% alcohol in it (that’s less than a Molson Light) and later measured their blood alcohol level (BAC) in their saliva.
Then the researchers put the bats in an obstacle course. That’s right, an obstacle course! They timed how long it took each bat to traverse the obstacle course (if they completed it) and counted how many times they ran into something or went in a circle. Afterwards, they gave them time to sober up before they released them back into the wild… presumably to go tell their friends about the crazy night they had. Ooohhh, was this gonna be funny!
To the researchers’ surprise, despite the fact that several bats had a BAC over 0.3% (the equivalent to a 150 pound person after 10 drinks), the bats on alcohol did not seem to be impaired in any way! They traversed the obstacle course just as fast and completed the course just as often as their kiddie-cocktail sugar-water drinking counterparts. They never even ran into anything.
So, I guess we’re not going to be entertained by drunken bat antics. But this is good news for the fruit-eating bats – Somehow, they are able to metabolize fermented fruit to get the caloric benefit without the risks of impairment. Now, if we could just figure out how they do that…
The moral of this story: Don’t drink alcohol when there are predators around unless you are a fruit-eating bat. And don’t challenge a fruit-eating bat to a drinking contest. He will drink you under the table!
Want to know more? Check this out:
Orbach DN, Veselka N, Dzal Y, Lazure L, & Fenton MB (2010). Drinking and flying: does alcohol consumption affect the flight and echolocation performance of phyllostomid bats? PloS one, 5 (2) PMID: 20126552