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 →
In what seems like a highly inefficient food procurement process, the majestic cormorant, a variety of seabird, dives to the sea floor in search of food.
Scientists with the Wildlife Conservation Society and the National Research Council of Argentina attached a camera to the back of a cormorant to track its dietary regimen. And they followed it for or nearly two minutes before it finds something suitable — 150 feet below the surface of the ocean. The birds typically eat fish and other marine life, and this cormorant is thought to have grabbed a snake-like swimmer. Continue reading →
The distinctive orange and black wings of monarchs (Danaus plexippus) have long been known to advertise their bitter taste and toxicity to potential predators. Recent work also showed that both the orange and black coloration of this species can vary in response to individual-level and environmental factors. Here we examine the relationship between wing color and flight performance in captive-reared monarchs using a tethered flight mill apparatus to quantify butterfly flight speed, duration and distance.
In three different experiments (totaling 121 individuals) we used image analysis to measure body size and four wing traits among newly-emerged butterflies prior to flight trials: wing area, aspect ratio (length/width), melanism, and orange hue. Results showed that monarchs with darker orange (approaching red) wings flew longer distances than those with lighter orange wings in analyses that controlled for sex and other morphometric traits. This finding is consistent with past work showing that among wild monarchs, those sampled during the fall migration are darker in hue (redder) than non-migratory monarchs.
Together, these results suggest that pigment deposition onto wing scales during metamorphosis could be linked with traits that influence flight, such as thorax muscle size, energy storage or metabolism. Our results reinforce an association between wing color and flight performance in insects that is suggested by past studies of wing melansim and seasonal polyphenism, and provide an important starting point for work focused on mechanistic links between insect movement and color.
Citation: Davis AK, Chi J, Bradley C, Altizer S (2012) The Redder the Better: Wing Color Predicts Flight Performance in Monarch Butterflies. PLoS ONE 7(7): e41323. doi:10.1371/journal.pone.0041323
Editor: Chuan-Chin Chiao, National Tsing Hua University, Taiwan
Received: January 25, 2012; Accepted: June 20, 2012; Published: July 25, 2012
Copyright: © 2012 Davis et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Funding: The authors have no support or funding to report.
Competing interests: The authors have declared that no competing interests exist.
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Courtesy Public Library of Science
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.
I recently completed the Wissahickon Valley Watershed Birdathon. This is a two day birding marathon in which teams from the Philadelphia area try to one-up each other to see or hear more bird species than the other teams. We found that sometimes it’s easier to hear a bird’s song, even though you can’t easily see the bird. Let’s face it – there’s wind in the trees, making movement that looks like a bird, and those pesky leaves – all making it really difficult to see those little guys.
With regard to hearing bird calls, the tide has definitely turned on available tools to help in the field. With smartphones becoming more and more readily available, bird-related apps are gaining popularity. This got me thinking about how one learns bird calls, songs, sounds and so on. What tools do you need, and what is the best way to learn? In discussing it, we all agreed that, though phone apps are nifty to have, and even downright useful, they can’t replace really getting to know the calls pretty well first. A birding app, like the iBird Pro 2, works great as a confirmation tool when calls can be similar sounding, but more time has to be spent on the songs alone in order to have even an inkling of where to start looking for the correct bird to go with the sound you are hearing.
There are a number of decent CD’s available for learning sounds. Since I live in the Eastern United States, I used A Field Guide to Bird Songs: Eastern and Central North America , which is designed to go along with the Peterson Bird Guides. There is also a western version, A Field Guide to Western Bird Songs: Western North America. These CD’s arrange the birds by similar sounding calls, which was helpful. (of course, if I ever spend much time in the west, I’ll have to learn a bunch of new ones!)
Another person on our team used the Field Guide To Bird Songs East by Stokes. I am not sure how they are arranged with regard to individual bird song, but my friend is one of the best birding-by-ear people around.
My personal recommendation would be to purchase two different CD types – that is, both of the recommended sets above or two differing other titles. If you have just one set, you get used to the birds being “fed” to you in a certain way. For example, all the woodpecker species together. But that’s not how it is in nature. You hear one, but not the others. By listening to a variety, you don’t become so “used to” hearing the sounds the same way.
Team Kestrel, as we are called, consists of three people – myself and two others – who know most bird calls (or chatters or songs). We all learned the long way, by listening to recorded bird sounds and getting out into the outdoors to hear them as well. This is, in my opinion, still the best way to become thoroughly familiar with the various bird calls. This year was the first time that we had my smartphone out in the field with us to help confirm any of those ornery “sound alikes”. That is, cases in which we may have had some disagreement, we used the iBird Pro 2 on my android phone. It was actually pretty great. The app is cheap – only 99 cents – and allows the user to easily search of any part of the bird name to bring it up. So we were able to simply search “warbler” and the whole list came up.
Birding apps are fun, cool and inexpensive, but can’t replace the patience of listening to other recorded media and good old fashioned trudging through fields, forests, streams and waterways.
The Santa Fe New Mexican – In hopes of increasing wind energy production in New Mexico while protecting wildlife and habitat, a coalition of energy companies, conservation groups and government agencies have come up with recommendations.
The group this week launched a website to list the “best management practices” for designing and siting wind facilities while protecting bats, raptors and other birds. The coalition says its recommendations are based on science but aren’t binding on any of the energy companies operating in the state.
The New Mexico Wind and Wildlife Collaborative involves eight energy companies, seven conservation groups and several agencies such as the New Mexico Department of Game and Fish and the U.S. Fish and Wildlife Service. Public Service Company of New Mexico, First Wind, Audubon New Mexico and Hawks Aloft are among the groups that met over the last two years to hammer out recommendations for wind farms.
“We were trying to create a process where birds would be considered in siting not just wind facilities, but all renewable energy sources such as solar,” said Christopher Ratay of Playa Lakes Joint Venture, a bird conservation group that helped facilitate the meetings. “Even though there are no state or federal regulations governing it, wind facilities want to try and avoid problems.”
Industry and conservation groups had to understand each other’s positions to reach agreements, Ratay said. Industry needed to make sure it can build wind facilities and transmit the electricity at a reasonable cost to consumers. Conservationists want wildlife and habitat protected.
While wind energy is considered a “green” renewable source of electricity, the facilities still can harm wildlife and habitat. The height of wind turbines, the design and length of the blades and the location of the towers can all impact birds and bats. Wind turbine pads and the roads to reach them fragment wildlife habitat, a special problem if the facilities are located in an area with threatened and endangered species.
Newer wind turbines and blades kill fewer birds than older ones. Still, if wind turbines are placed in the flight path of endangered raptors and migratory birds, the deaths of even a few create a problem, according to biologists.
Industry needs to site wind facilities where there’s plenty of wind and transmission lines are close.
“We wanted to make sure any guidelines put out would be achievable but would satisfy all the parties,” said Matt Desmond of First Wind, a wind-energy development company.
The group developed best management practices for 12 wildlife species and for critical habitat such as playas.
What remains to be seen is how many wind-energy companies will follow the recommendations.
For more information about the collaboration and to see best management practices, visit www.pljv.org/windandwildlife/nm/nmwwc.php.
Contact Staci Matlock at 986-3055or email@example.com.