Tag Archives: songbirds

Scientists Track, For the First Time, One of the Rarest Songbirds on Its Yearlong Migration

Kirtland's Warbler

(Wendy Mitman Clarke; March 6, 2017)

At .48 ounces, your average Kirtland’s warbler weighs about as much as a handful of tortilla chips (seven, stacked), or about the same as one baby carrot. And every year, this rare North American songbird travels nearly 4,000 miles round trip, across mountain ranges, the body of a continent, the Gulf Stream and open ocean. Most of this journey has been a mystery, until now.
Using light-level geolocators, Smithsonian scientists have for the first time tracked and mapped the migratory paths of Kirtland’s warblers for an entire year, following them from their breeding grounds in Michigan to their winter homes in the central Bahamas and back. The scientists hope the data will enable conservation managers to better understand how to manage habitat for the warblers, which were close to extinction in the 1970s and have made a significant comeback as an endangered species.

The research, published in the Journal of Avian Biology, also represents a breakthrough for studying other small species’ migrations, which are an elusive but pivotal element of their lives.

“However difficult it may be, it is critical that we understand the full annual cycle of birds, not just what is happening during breeding,” says Nathan Cooper, lead author of the study and postdoctoral fellow at the Smithsonian’s Migratory Bird Center, part of the Smithsonian Conservation Biology Institute. “There is a significant amount of mortality for songbirds that happens during migration, indicating that the conditions birds encounter while migrating might be major factors in a species’ overall success or failure.”

“We know so little about migration for so many species,” says Pete Marra, head of the Migratory Bird Center and co-author on the paper. “This is the rarest songbird in North America, one of the most endangered. The goal is to move toward tracking the same individuals throughout the year to understand where and why birds are dying, and we’re getting closer with this species.”

Kirtland’s warblers are easy to study in one respect; they only nest in dense, young jack pine forests predominately in specific regions in Michigan. But those forests depend upon frequent fires to propagate the jack pines’ seeds, and fire suppression in the mid-century, coupled with nest predation by the brown-headed cowbird, devastated the species. In 1966 the U.S. Fish and Wildlife Service declared the birds endangered; in 1974, researchers identified only 167 singing males.

By planting new young jack pine forest and implementing a cowbird removal program, conservation managers helped the warblers begin to recover their numbers. Today, their population is estimated at about 2,300 males. It’s a success story, but continued management is crucial.

Although scientists know a great deal about the birds on their breeding grounds in Michigan, they know less about their distribution in the Bahamas during the winter, and migration—which kills an estimated 44 percent of Kirtland’s populations—has remained an unknown.

“Given that they’re flying 2,000 miles in two weeks, it makes a lot of sense that there could be a lot of mortality during that period,” Cooper says. “But we don’t know if it’s driven by things that happen during migration, or if it is set up by events that happen during the wintering period.” For instance, a drought in the Bahamas can mean less food, so the birds might be malnourished before they even begin the strenuous, stressful flight of migration. “That’s why things like climate change [contributing to drought in the Bahamas] can affect migration and, in turn, the breeding period.”

The more widely used satellite and GPS tracking devices that work well on larger animals are too bulky and heavy for most birds, but in the 1990s, British researchers developed light-level indicating devices that were small enough to attach to wandering albatrosses. The concept of using light levels to determine location has been used by mariners for centuries. By determining precise sunrise, midday and sunset times, one can calculate a rough position, because the length of a day varies predictably depending upon one’s latitude and longitude.

New light-level geolocators are finally small enough for even diminutive songbirds to carry them, Cooper says.

“They measure the intensity of sunlight every two minutes and save it to the device. It gathers that data over the whole year. We can estimate sunrise and sunset time every day of the year, and from that you can get day length and solar noon,” Cooper says. That data enables researchers to roughly estimate and map the birds’ location.

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Study of songbird migrants demonstrates the importance of temperature in the decision to begin migration

migration

(DE GRUYTER, 2017-02-10)

Around the world, no matter where we are, we can usually expect the weather to change from one season to the next. In North America, the warm days of summer eventually turn into the cooler days of  autumn, and these changes are vital to a lot of the animals that inhabit the region as they trigger the urge of animals to prepare for winter. Migratory animals, like songbirds, use these predictable weather changes as environmental cues to tell them when it’s time to migrate south. But with the earth now becoming warmer each year, birds can no longer rely on the once predictable climate.  As  autumns are becoming milder, ornithologists keep pondering on how it could be affecting birds’ migratory decisions. Now, a new study just published by De Gruyter’s online journal Animal Migration, has experimentally investigated how birds use temperature as a signal to migrate.

The study led by Adrienne Berchtold from the Advanced Facility for Avian Research at the University of Western Ontario, focused on one songbird species that is known to rely on weather for its migratory journey: the white-throated sparrow. The bird migrates from Canada to the southern United States each  autumn, and it tends to migrate later in the  autumn than other migrants, basing its journeys on when the weather provides opportunities for flight.

To figure out the underlying pressures that drive the birds to migrate, the researchers captured white-throated sparrows during one  autumn migration and placed them in specially-designed bird cages equipped with high-tech monitoring gear that kept track of how active the birds were by day and night. The scientists then changed the room temperature throughout the experiment to see how the birds would react. When the temperature dropped to chilly 4ºC, in an attempt to mimic the typical fall conditions in the northern part of the flyway, the birds all became restless at night, signifying they were in a migratory state. When, in turn, the temperature was raised to a warm 24ºC, none of the birds showed signs of migratory restlessness, indicating they were under no pressure to depart in these conditions.

These results will have considerable implications for the future of the migration as this and other bird species rely on predictable weather changes to leave home for the season. In North America, the continuous trend in soaring  autumn temperatures could delay the birds migration. Yet another more drastic possibility is that the birds would decide, perhaps unsurprisingly, to stay put and not to migrate at all. In fact, a recent paper in this same journal found this very pattern is happening in the population of American Robins of North America, who are increasingly deciding not to migrate.

According to Andrew Farnsworth, a Research Associate at the Cornell Lab of Ornithology who studies bird migration, “This type of research gives us more of the clues that scientists need to understand how birds respond, and might respond in the future, to changes in environmental conditions they experience. Considering these findings in light of previous research on nocturnal migratory restlessness from the mid to late 20th century, and more importantly, recent research on fuel accumulation and photoperiodicity, these results add to our growing understanding of how birds migrate and even how their migration evolved. Furthermore, given the predicted changes in global temperatures from human activities, these findings highlight the potential for dramatic changes to movements for many migratory species.

The tiny corner of Asia where an Endangered songbird is thriving

(Alex Dale, 23 Feb 2017)

But unfortunately, it’s this same rich, powerful melody which is threatening to silence the species forever. As we reported during our 2016 Red List coverage, keeping songbirds as pets is an integral part of South-East Asian culture. In Indonesia in particular, streets are lined with chirping cages, and songbird contests are big business.

But as the streets grow louder, forests are falling silent. The widespread trapping of wild songbirds to meet demand for local bird markets, is driving many species endemic to the area towards extinction – with the prized Straw-headed Bulbul one of the more badly affected.

“Across much of Southeast Asia, the Straw-headed Bulbul has been relentlessly trapped from the wild to be later sold in the bird markets of Java, Kalimantan, Sumatra and Peninsular Malaysia,” says Yong Ding Li from The Australian National University. “The bird has gone extinct from Thailand and most parts of Indonesia where it used to be found, including the whole island of Java. Its populations have also collapsed across Malaysia.”

Check out its song in the video below:

However, there is one small haven where the Straw-headed Bulbul’s presence isn’t just stable, but actually growing louder: Singapore.

This is according to findings from a recent study led by Ding Li, and published in the journal Bird Conservation International. The study saw authors from The Australian National University and Nature Society (BirdLife in Singapore) gather data from more than 15 years of the Annual Bird Census, a yearly bird survey organised by Nature Society.

The result was an encouraging discovery: wild populations of the Straw-headed Bulbul have steadily risen in Singapore over that time period, and the country is now something of a global stronghold. Indeed, Singapore might now harbour more Straw-headed Bulbuls than anywhere else on the planet.

The increases were not noted on mainland Singapore, however, where populations merely remained stable – although given the Straw-headed Bulbul’s plight elsewhere, even this is a big win. Rather, the increases were documented on the small island of Pulau Ubin, situated north-east of mainland Singapore, and one of the country’s last remaining rural areas. Here, the species’ population increased by nearly 4% a year.

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Songsters of Singapore: An Overview of the Bird Species in Singapore Pet Shops

James A. Eaton, Boyd T. C. Leupen and Kanitha Krishnasamy,February 2017)

Summary

Singapore has a long history of involvement in the bird trade. Recent analysis of the trade in CITES Appendix I and II-listed birds from over 30 countries between 2005 and 2014, highlights that Singapore issued commercial import- and export permits for a total of 225 561 and 136 912 birds respectively. This involved 212 species, of which 30 were classified by the IUCN as Vulnerable, Endangered or Critically Endangered.

Another study on the import and export of CITES-listed birds from the Solomon Islands in 2011 found Singapore to be the importer of 72% of the 68 000 wild-caught and reportedly captive-bred birds from the Solomon Islands, with the vast majority of these birds subsequently being re-exported.

In both studies, attention was drawn to the illegal sourcing of birds, and Singapore’s role in moving these birds into the legal global market.

TRAFFIC undertook a rapid assessment of the open bird trade in Singapore’s pet shops. Surveys of 39 pet shops, were conducted over four days in November and December 2015. The most heavily traded CITES Appendix I-listed bird was the Yellow-shouldered Amazon Amazona barbadensis with at least 16 recorded individuals. Overall, 41 CITES Appendix II species were recorded, totalling 350 individuals.

From the IUCN Red List of Threatened Species, only one Critically Endangered species was observed; Yellow-crested Cockatoo Cacatua sulphurea (two individuals).

Two Endangered species were encountered, namely

  • Lilac-crowned Amazon Amazona finschi (n=3) and
  • Sun Parakeet Aratinga solstitialis (n=16), although two further species,
  • Grey Parrot Psittacus erithacus (n=15) and
  • Straw-headed Bulbul Pycnonotus zeylanicus (n=1), were subsequently (December 2016) uplisted to this category (from Vulnerable).

Eight Vulnerable species (excluding Grey Parrot and Straw-headed Bulbul, but including the December 2016 uplisted Greater Green Leafbird Chloropsis sonnerati and Javan White-eye Zosterops flavus were found, totalling 66 individuals.

Sixty-seven percent (9452) individuals of seven species) of the total number of encountered birds were flagged as species of immediate concern at the first Asian Songbird Crisis Summit, held in Singapore in 2015.

Recommendations

At present, it is not possible to determine if the bird trade in Singapore is occurring illegally, and if so, to what extent. This can only be done if the following information is made available:

• The quantity of CITES species and individuals registered for import and export, and disclosure of any quotas set by the Government for trade.

• Captive breeding activities within Singapore, including information on registered breeders and the volumes of species meant for domestic and/or international trade.

• Processes and protocols in place to regulate non-CITES, non-protected species that are being imported and exported from Singapore.

The Animal Welfare and Control Division of AVA, which issues licenses to pet shops, should conduct regular inspections to ensure that shops have the correct permits for all imported and captive-bred species, and when applicable, CITES-permits for CITES-listed species. In order for consumers to make wise purchasing decisions, AVA should introduce a regulatory requirement (including penalties for ITS violation) for shop owners to provide information on the name of  the bird, its CITES status (if it involves a CITES-listed species), and its source (wild-caught/captive  bred). This would allow consumers to make a conscious decision on whether to buy sustainably sourced pets or not.

Winter Berries for Winter Birds

 

(Rhiannon Crain, February 9, 2017)

In the spring and summer, when bugs are buzzing and plants are blooming, a bird’s diet will most likely consist of a variety of abundant, protein-rich insects. In northern regions where warm seasons change to cold, those insects become fewer and harder to find, convincing many avian species to migrate to tropical locations where insects are found year-round, or to change-up their primary food source–relying not on insects, but on winter berries. Read on to learn about putting this valuable habitat feature to work.

Migratory neotropical songbirds are usually insectivorous and are among many who make the long journey between North and South America to feed almost exclusively on insects and other invertebrates, like worms. Many warblers, like the Common Yellow-throat shown above, will migrate to North America during breeding season to take advantage of the abundant insect foods that appear in the spring and summer and return south as those food sources dwindle. They almost never eat food from plants, which is one reason you won’t see them at your feeders.

On the other hand, many songbirds are year-round residents and will stay in northern latitudes even during the coldest winter months. They are able to eat a larger diversity of foods as the seasons change, including berries, seeds, and nuts, that are available from native shrubs and trees. The image above, taken in November, shows an American Robin in Ontario, Canada investigating some Mountain-Ash berries, still lingering from when they ripened in early autumn. Year-round residents rely on persistent berries, like these, to sustain them through the winter season.

In the spring and summer, this same robin will be found gorging on insects, like caterpillars in the image above, as soon as this food source becomes available. Research has even suggested that these seasonal shifts in food abundance help cue physiological changes that prepare birds for breeding season. A landscape with berry-producing native trees and shrubs provides the resources that support these seasonal cues by producing high-fat berries in the fall and attracting insect food in the spring.

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How Will an Arctic-Breeding Songbird Respond to Taller Shrubs and Warmer Temperatures?

(Heather McFarland, 1 Feb, 2017)

How will songbirds that nest in tundra respond as the Arctic transforms into a warmer and shrubbier environment? This is the question that drove us to study a small songbird known as the Smith’s Longspur. Endemic to North America, this songbird breeds in only a few remote mountain valleys in Canada and Alaska, making it particularly susceptible to changes at northern latitudes. Smith’s Longspur’s are also unique in that they are polygynandrous. This is a rare mating strategy where both sexes are polygamous, and birds of either sex may mate with up to three individuals each breeding season. Rather than a single male and female establishing a territory, Smith’s Longspurs usually form larger groups called neighborhoods which contain many inter-mated individuals. Since this mating strategy is poorly understood and so different from other tundra nesting songbirds, it is difficult to predict how breeding Smith’s Longspurs may respond to climate change. Therefore, prior to further change, baseline information about breeding requirements is needed. To fill this void, we monitored more than 250 Smith’s Longspur nests between 2007 and 2013 in the Brooks Range of Alaska. All of the nests were found in open tundra areas, and females never placed their nests in tall vegetation.

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