Smithsonian Science » Migratory Bird Center

Eighty percent of urban fledgling catbirds killed by predators

John Barrat — Thu, 17 May 2012 13:00:15 +0000

Scientists from the Smithsonian Migratory Bird Center have found that fledgling catbirds living in the suburbs are extremely vulnerable. Almost 80 percent are killed by predators before they reach adulthood. Nearly half of the deaths are connected to domestic cats. The team studied catbird nests in 3 suburban neighborhoods in Maryland: Spring Park, Opal Daniels Park, and Bethesda. Learn more about this 2011 study by clicking here. (Catbird photo by Gerhard Hofmann)

Invasive pythons in Florida now stealing bird eggs straight from the nest

John Barrat — Fri, 06 Apr 2012 11:42:00 +0000

Smithsonian scientists and their colleagues have uncovered a new threat posed by invasive Burmese pythons in Florida and the Everglades: The snakes are not only eating the area’s birds, but also the birds’ eggs straight from the nest. The results of this research add a new challenge to the area’s already heavily taxed native wildlife. The team’s findings are published in the online journal Reptiles & Amphibians: Conservation and Natural History.

Image right: Burmese pythons (Python molurus bivittatus), native to southern Asia, have taken up a comfortable residence in the state of Florida, especially in the Everglades. In addition to out-competing native wildlife for resources and habitat, the pythons are eating the native wildlife. (Photo by Sarah L. Stewart)

Burmese pythons, native to southern Asia, have taken up a comfortable residence in the state of Florida, especially in the Everglades. In addition to out-competing native wildlife for resources and habitat, the pythons are eating the native wildlife. Burmese pythons (Python molurus bivittatus) were first recorded in the Everglades in 1979—thought to be escaped or discarded pets. Their numbers have since grown, with an estimated breeding population in Florida in the tens of thousands.

Image left: Five of ten entire Guineafowl eggs regurgitated by a Burmese python. (Photo: R.W. Snow, Everglades National Park)

In an ongoing study to better understand the impact of this snake in the Everglades, scientists from the Smithsonian Institution, the National Park Service and others have been examining the contents of the digestive tracts of pythons in the area. They have shown that Burmese pythons consume at least 25 different species of birds in the Everglades, but until now no records documented this species eating bird eggs.

“This finding is significant because it suggests that the Burmese python is not simply a sit-and-wait predator, but rather is opportunistic enough to find the nests of birds,” said Carla Dove, ornithologist at the Smithsonian’s Feather Identification Lab in the National Museum of Natural History and lead author of the study. “Although the sample size is small, these findings suggest that the snakes have the potential to negatively affect the breeding success of native birds.”

Image right: Two Limpkin (Aramus guarauna) crushed but intact eggs (top) recovered from a Burmese python digestive tract and compared to a reference Limpkin specimen from the Smithsonian’s collection (below) for size and color patterns. The arrow shows fragments of eggshells from the python sample placed on the Smithsonian specimen for color comparison. (Photo by Don Hurlbert)

Scientists collected a 14-pound male python that was 8 1/2 feet long near a property with free-ranging guineafowl. The snake regurgitated 10 whole guineafowl eggs soon after it was captured. The team discovered the remains of two bird eggs in another python collected for the study―a 30-pound female more than 10 feet long. Scientists used DNA tests on the membrane of the crushed eggs and comparisons of the shell fragments with egg specimens in the Smithsonian’s collection to determine what the female snake had eaten. Their research revealed the species to be the limpkin (Aramus guarauna), a large wading bird found in marshes and listed as a “species of special concern” by the Florida Fish and Wildlife Conservation Commission.

Image left: Everglades National Park wildlife biologist Skip Snow in the South Florida Research Center lab with rooster remains recovered from a captured Burmese python. (Photo by Lori Oberhofer, National Park Service)

There are several species of snake known to eat bird eggs. Those species are equipped with pointed or blade-like extensions on the vertebrae in their esophagus that punctures the eggshell, making it easy for the snake to crush the egg and digest its contents. Burmese pythons do not have these adaptations. However, the pythons studied were so large in relation to the eggs they ingested that the scientists believe these specialized vertebrae may not have been needed.

“Our observations confirm that invasive Burmese pythons consume not only adult birds but also eggs, revealing a previously unrecognized risk from this introduced predator to nesting birds,” said Dove. “How frequently they are predating on bird eggs is hard to know.”

In an earlier stage of the study, the scientists collected more than 300 Burmese pythons in Everglades National Park and found that birds, from the 5-inch-long house wren to the 4-foot-long great blue heron, accounted for 25 percent of the python’s diet in the Everglades.

Extremely rare Guam rails hatch at the Smithsonian’s National Zoo

John Barrat — Fri, 16 Mar 2012 12:29:02 +0000

As Washington, D.C.’s unseasonably warm winter turns into spring, a baby boom is underway at the Smithsonian’s National Zoo. Two Guam rail (Gallirallus owstoni) chicks hatched March 3 and 4; they join six others in the Zoo’s collection—three of which live at the Smithsonian Conservation Biology Institute in Front Royal, Va. This brings the total population of these small, flightless birds to 162 individuals. Each hatching is significant—the International Union for Conservation of Nature lists these birds as extinct in the wild.

In about six weeks, keepers will separate the chicks from their parents, and Zoo veterinarians will perform a routine medical exam and take feather samples to determine their sexes.

(Guam rail photos by Jim Jenkins, FONZ Photo Club)

To date, 82 chicks have hatched at the Zoo and SCBI, and each provides scientists with the opportunity to learn about the growth, reproduction, health and behavior of the species. The Zoo sent 29 Guam rails to the government of Guam for release and breeding, and an additional 25 birds have gone to other institutions to breed.

Guam rails flourished in Guam’s limestone forests and coconut plantations until the arrival of the brown tree snake (Boiga irregularis), an invasive species that stowed away in military equipment shipped from New Guinea after World War II. Because these reptiles had no natural predators on Guam, their numbers grew and they spread across the island quickly. Within three decades, they hunted Guam rails and eight other bird species to the brink of extinction.

In 1986, Guam’s Department of Aquatic and Wildlife Resources captured the country’s remaining 21 Guam rails and sent them to zoological institutions around the globe—including the National Zoo—as a hedge against extinction. The Association of Zoos and Aquariums created a Species Survival Plan for the birds. The SSP pairs males and females in order to maintain a genetically diverse and self-sustaining population.

Today, 118 Guam rails are thriving on two islands near the mainland: Rota and Cocos. The availability of release sites continues to shrink, however, due to deforestation and human expansion. Controlling the brown snake population remains a significant challenge as well, though researchers have made progress in developing a variety of barriers, traps and toxicants. Forty-four birds reside in zoos and other facilities in North America. Visitors to the Smithsonian’s National Zoo can see these birds on exhibit in the Bird House. In stark contrast to their brown-and-white-plumaged parents, Guam rail chicks sport black downy feathers.

Uganda park rangers with cell phones may help stop next world influenza epidemic

John Barrat — Fri, 03 Feb 2012 18:16:13 +0000

When West Nile virus swept across the New York City region in 1999 and then, in subsequent years, across almost all of the continental United States, “people were finding dead crows and other birds all over the place,” says Peter Marra of the Migratory Bird Center at the Smithsonian Conservation Biology Institute. “We didn’t see the actual virus moving across the landscape, but we did see the devastation it caused through the remains of birds.” The disease was passed from birds to humans primarily by the tiger mosquito.

Today, Marra is helping launch an Animal Mortality Monitoring Program (AMMP) in Africa sponsored by the United States Agency for International Development that will alert authorities to animal deaths—“mortality events”—that occur on a larger-than-normal scale. Known as AMMP, the network is intended to serve as an early warning system for emerging infectious diseases that can pass from animal populations into the human population. Recently, Marra and his collaborator Isabelle-Anne Bisson, a research associate at the Migratory Bird Center, took a few minutes to answer some questions about this new initiative.

Image right: A flag representing “56 dead rats” set out during an animal mortality monitoring training workshop for park staff at the Queen Elizabeth Conservation Area in Uganda.

Q: What is the aim of the animal mortality monitoring program in Africa?

A: Marra: In cases of zoonotic diseases—such as West Nile virus and Avian Influenza which each began in animals and then jumped to humans—an epidemic of human sickness usually occurs after there’s already been a noticeable sickness in animals. By having local people keeping an eye out for sick and dead animals we think we have the potential to get an early warning on emerging zoonotic pathogens before they move to the human population. We want to have some sort of surveillance mechanism out there that is looking for sick and dead animals that have fallen victim to an emerging disease. This way we may catch a disease before it becomes a human epidemic.

Image above: Isabelle-Anne Bisson conducts a workshop with park staff from Queen Elizabeth Conservation Area in Uganda. (All images courtesy Isabelle-Anne Bisson)

Q: Why Africa?

A: Marra: We are starting in Uganda because it, as well as other “hotspots” in Africa, tend to be places where you get a lot of zoonotic diseases occurring. In such areas there is a lot of mixing of things—people, domestic animals, wild animals—that don’t normally come together. People are hunting animals and eating wild game and there’s just a lot of human-animal interface.

Once a pathogen emerges and disease begins to appear in hosts, given how much globalization is taking place today and how much trade there is all over the planet, an epidemic can move today in ways that we never would have predicted. The tiger mosquito that may have brought West Nile Virus to North America could have easily been transported on planes. There’s a lot of illegal trade in animals and food that goes on too. Every time you move an animal, legally or illegally, you not only move the animal but also move what is inside the animal—including pathogens and parasites. There are a lot of different factors that determine whether or not and how a pathogen can move.

Image right: A park staff member finds the first flag set out by AMMP staff.

Q: How is the AMMP network being launched?

A: Bisson: In April 2011 we launched the first pilot project in the Queen Elizabeth Conservation Area with the Uganda Wildlife Authority. Some 50 Nokia mobile phones were deployed. We started with an intensive month-long training program, which included several workshops where park staff learned how to use the phones and the mobile data collection application EpiSurveyor. The phone acts as a small mobile computer where staff can enter animal mortality events using EpiSurveyor while on field patrols.

We next used “mock” dead animals by printing yellow flagging tapes that contained project logos and information the staff needed to enter once they found a flag. For example, a flag might say “56 dead rats.” We distributed more than 100 of these flags across the park tied to trees and recorded the GPS data for each flag.

Image left: During a training session, park staff in Uganda learn to capture data from a flag representing “mock” dead animals on a Nokia cell phone.

When park staff found a flag, they entered its data into the cell phone and the phone also captured the flag’s GPS position. The data is sent to a central server via cellular networks and anyone with a computer, Internet connection and access to the account can view the data in real time.

Q. How did the park staff do finding the flags?

A: Bisson: From May to August park staff looked for the flags while on patrol and entered the data for the flags they found. From August to September we returned to Uganda to evaluate the training and practice and speak to park staff for feedback.

We heard a lot of stories about taking hours to find a single flag and their frustrations with the network, but all-in-all the feedback was positive—they love the phones and they love EpiSurveyor. One quarter of the flags were recovered of which 65 percent were entered correctly without missing data. Some flags were eaten by ants, others were destroyed by elephants, some disappeared mysteriously while a few had faded to a pale, imperceptible yellow.

All-in-all the workshops exceeded our expectations. Queen Elizabeth Conservation Area staff are now ready to monitor real animal deaths and we plan to fully integrate the program into existing Uganda Wildlife Authority systems at the end of June 2012. We are also working on the development of a custom mobile phone data form application with a local company MindAfrica.

Image above: Uganda Wildlife Authority staff celebrate following the successful completion of the AMMP workshop.

Q: What follows when a real mortality event is reported?

A: Marra: Another main AAMP partner is RESPOND, a project that links schools of public health and veterinary medicine in Africa with institutions in the United States to help strengthen their ability to identify and respond to outbreaks. Once a mortality event occurs an animal pathologist will come to the scene, someone say from the School of Veterinary Medicine at Makerere University in Uganda, and take samples of animal tissues and transport them to a lab for analysis.

These projects are part of a larger Emerging Pandemic Threats program overseen by USAID, which includes PREDICT, a program focused on responding to, identifying, preventing and preparing for emerging pandemic diseases.

Q. Other than national park staff what other groups will you be working with to establish an AMMP network?

A. Marra: Our goal now is to expand the program to people in the agricultural sector in Uganda—people with large and small farms, say down to only one cattle herd.

But on a larger scale, it is basically a sound idea to keep track of all animal mortality, period. AMMP is focused on emerging infectious diseases, but I have had a long-time interest in developing a central database for keeping track of and quantifying animal mortality. We don’t have anyone compiling these sort of data today…say how many birds and what species were killed by airplanes, how many birds and what species are killed by wind turbines…. There are all sorts of ways animal mortality data can be analyzed and actions we can take to minimize the impacts on birds and other animals and, thus, minimize the impacts on humans. Many places in the world are prime areas for a dead animal surveillance networks.

Urban songbirds adjust melodies to adapt to life in the big city, Smithsonian scientists find

John Barrat — Mon, 05 Dec 2011 15:33:03 +0000

Cities tend to be noisy places—even having a simple conversation among the general hubbub can be difficult unless you adjust your tone of voice to be heard. A study published in November’s issue of Behavioral Ecology found that the same could be true for songbirds in urban areas. For the first time, researchers from the Smithsonian Conservation Biology Institute’s Migratory Bird Center analyzed how songbirds are affected by both general noise and the acoustics of hard human-made surfaces in urban areas. Their findings suggest that some species are altering their songs to adjust to either human-made noise or human-made objects, but the birds seem to have more difficulty altering their song in the presence of both.

Image right: Northern cardinal (Click to enlarge. All photos by Gerhard Hofmann, Hofmann & Scheffer Photography)

“Animal vocalizations are specifically adapted to both the structural and acoustic characteristics of their local environment,” said Peter Marra, a co-author of the study and an SCBI ecologist. Marra oversaw and helped design the research. “In order to survive and reproduce, it is imperative for birds to be able to transmit their signals to each other. Now it seems they may be having trouble doing so in urban areas.”

Ambient city noise masks certain lower sound frequencies, making it more difficult for birds to hear one another’s calls over long distances. In addition, hard surfaces—such as buildings—can reflect and distort higher frequency sounds by scattering sound waves and creating multiple reverberations. This can confuse birds and make it difficult for them to pinpoint the source of the call.

Image left: Gray catbird

The results of the researchers’ analysis showed that although there was some variation by species, the birds tended to sing higher notes in areas where there was general noise. The birds tended to sing lower and deeper notes, however, in areas where there were many buildings and hard surfaces. But when the two conditions combined, the birds had trouble altering their songs to accommodate both factors.

“At this point we don’t know exactly how birds adjust their songs,” said Jenélle Dowling, an SCBI intern at the time the research was conducted and lead author of the study. “We expect different species, which differ in their capacity to adjust frequency and type, to respond differently to reverberation and noise.”

By vocalizing, birds are able to identify and locate other members of their species, attract mates and defend their territory. So their ability to adapt to urban living could affect their survival. As urban areas develop rapidly, researchers will continue to investigate how sound from these busy areas affects birds and the effects of development on sound transmission.

Image right: House wren

“This is just another example of how humans continue to impact wildlife,” Marra said. “We now need studies to determine if these changes in song translate into differences in reproductive success,” he added.

This research was carried out in conjunction with the Smithsonian’s Neighborhood Nestwatch citizen science project, where participating citizens allow the researchers to use their property as study sites, as well as volunteer their time to assist with data collection.

Dowling, is currently a doctoral candidate at the Cornell Laboratory of Ornithology in New York. Marra is a conservation scientist at SCBI and advised Dowling. They worked in collaboration with researcher David Luther, who is a term assistant professor in the biology department of George Mason University in Virginia.

Illustrations of the nest and eggs of birds of Ohio

John Barrat — Fri, 09 Sep 2011 14:08:49 +0000

Illustrations of the nest and eggs of birds of Ohio was published in the small town of Circleville, Ohio, from 1879 to 1886 through the dedicated efforts of the family and friends of a young woman named Genevieve Jones. Despite being produced not just by amateurs but largely by women, far from the publishing houses and intellectual centers of 19th-century America, the book was hailed as an extraordinary achievement from the moment its first few plates were published. To learn more click this Smithsonian Libraries’ link. Shown here: wood thrush eggs and nest.

It’s no sweat for salt marsh sparrows to beat the heat if they have a larger bill

John Barrat — Thu, 21 Jul 2011 11:43:12 +0000

Birds use their bills largely to forage and eat, and these behaviors strongly influence the shape and size of a bird’s bill. But the bill can play an important role in regulating the bird’s body temperature by acting as a radiator for excess heat. A team of scientists have found that because of this, high summer temperatures have been a strong influence in determining bill size in some birds, particularly species of sparrows that favor salt marshes. The team’s findings are published in the scientific journal Ecography, July 20.

Images right and left below: The savannah sparrow is one of the several sparrow species that showed a difference in bill size depending on the daily high summer temperatures of their salt marsh breeding habitats.

Scientists at the Smithsonian Migratory Bird Center at the Smithsonian’s Conservation Biology Institute and colleagues examined five species of sparrow that inhabit salt marshes on the East, West and Gulf coasts of North America. While these marshes are very similar in makeup and structure, the main difference among them is summer temperatures.

Focusing on 10 species and subspecies of tidal salt marsh sparrow, the team measured 1,380 specimens and found that the variation in the sparrows’ bill size was strongly related to the variation in the daily high summer temperatures of their salt marsh breeding habitats—the higher the average summer temperature, the larger the bill. Birds pump blood into tissue inside the bill at high temperatures and the body’s heat is released into the air. Because larger bills have a greater surface area than smaller bills, they serve as more effective thermoregulatory organs under hot conditions.

On average, the study found the bills of sparrows in marshes with high summer temperatures to be up to 90 percent larger than those of the same species in cooler marshes.

Image right: The song sparrow is one of the several sparrow species that showed a difference in bill size depending on the daily high summer temperatures of their salt marsh breeding habitats.

“It is known that blood flow is increased in poorly insulated extremities in some animals, like a seal’s flippers, a rabbit’s ears and the wattles of a turkey helping hot animals to cool down. The bill of a bird can function in much the same way allowing birds to dump heat,” said Russ Greenberg, director of the Smithsonian Migratory Bird Center and lead author of the research. “Being able to cool down and not loose excess body moisture is particularly important since these birds live in an environment with direct sun and limited access to fresh water.”

The scientific theory known as Allen’s Rule states that warm-blooded species from colder climates usually have shorter limbs or appendages than the equivalent animals from warmer climates. The team’s new findings are a new example of Allen’s Rule that confirms the importance of physiological constraints on the evolution of vertebrate morphologies, even in bird bills.

The research team is working with physiologists from Brock University in Canada, employing thermal imaging to develop a more detail picture of how song sparrows that live in dunes and marshes along the Atlantic coast use their bills to stay cool.–Johnny Gibbons

“Extinct” birds reappear in rainforest fragments in Brazil

John Barrat — Thu, 23 Jun 2011 11:16:16 +0000

Bird species in rainforest fragments in Brazil that were isolated by deforestation disappeared then reappeared over a quarter-century, according to research results published today in the journal PLoS (Public Library of Science) ONE.

Scientists thought many of the birds had gone extinct.

Image left: The White-plumed Antbird has gone “extinct,” then returned, several times in the forest. Click to enlarge. (All photos by Phillip Stouffer/LSU)

The research was funded by the National Science Foundation (NSF), and conducted in cooperation with Projeto Dinâmica Biológica de Fragmentos Florestais, Instituto Nacional de Pesquisas da Amazônia and the Smithsonian Tropical Research Institute in Manaus, Brazil.

Lead author Philip Stouffer, an ornithologist at Louisiana State University and co-authors of the paper–Erik Johnson at the National Audubon Society; Richard Bierregaard at the University of North Carolina, Charlotte; and Thomas Lovejoy at The Heinz Center in Washington, D.C.–measured bird populations over 25 years in 11 forest fragments ranging from 2.5 acres to 250 acres in the Amazon rainforest near Manaus, Brazil.

Image right: View from the edge of a forest fragment; birds regularly move through to recolonize the fragments.

In the first decade of the long-term study, birds abandoned forest fragments and, ornithologists believed, went extinct. Then in the past 20 years, many bird species returned, while others went extinct or remained extinct.

“Through long-term observations of fragmentation in tropical forests, this study provides verification that local extinction is accompanied by continual recolonization, dependent on habitat size,” said Saran Twombly, program director in NSF’s Division of Environmental Biology, which funded the research.

Image left: The black-banded woodcreeper, shown here, is unlikely to survive in forest fragments.

Although species loss following habitat changes can be inferred, long-term observations are necessary to accurately identify the fate of bird populations, said Stouffer.

As the project began, bird populations were tracked before the forests were cut.

During the first year after cutting, bird species disappeared in what the researchers call “localized extinction,” meaning a species has disappeared from a particular area.

The area was fragmented in “cookie cutter chunks” as a result of policies that encouraged use of the land–mostly for cattle–but required landowners to leave a portion of the area uncleared.

Image left: The Black-throated Antshrike may not be able to recolonize fragments of the forest.

Bird populations were measured before the deforestation process began, then again in 1985, 1992, 2000 and 2007.

Now agriculture has diminished, and areas where fragments meet nearby forests are recovering, Stouffer said. “Early on, the small fragments lost most of their understory birds, and the area that was cut had no forest birds at all.”

Between the time the forest fragments were created and 2007, when the most recent measurements were taken, all fragments lost bird species, Stouffer said.

Losses ranged from below 10 percent in the largest, least fragmented areas to around 70 percent in the smallest, most fragmented spots.

Both extinction and colonization occurred in every interval. In the last two samples–taken in 2000 and 2007–extinction and colonization were approximately balanced.

Image right: This pasture has been abandoned; its regrowth will allow some birds to return to the forest.

The extinction process started with birds leaving or dying out. Now, they’re coming back.

Of the 101 species netted–trapped with a fine-mesh “mist net”–before deforestation, the researchers detected 97 in at least one forest fragment in 2007.

“A handful of species have ‘gone extinct,’ but many more species are in flux,” Stouffer said. “They come and go.”

The project measured only understory, resident birds and not those that live in the forest canopy or may migrate.

“Our samples are snapshots in time,” said Stouffer. “They show that forest fragments have the potential to recover their biodiversity if they’re in a landscape that can rebound.

“They’re not doomed.”

The research demonstrates some of the ways birds exist in a human-modified environment, as well as the effects of allowing a forest to regenerate.

“If we consider a balance of abandoned and returned forests–within a 20-year window–birds will begin to treat the fragments as continuous forest,” Stouffer said.

“Although a small subset of species is extremely vulnerable to fragmentation and predictably goes extinct, developing second-growth forest around fragments encourages recolonization.”

Species biodiversity in today’s forest fragments reflects local turnover, not long-term attrition of species, the scientists found.

They think similar processes could be operating in other fragmented ecosystems, expecially ones that show unexpectedly low extinction rates.–Source: National Science Foundation

Manakins, birds of tropical forests, form alliances for common good

John Barrat — Wed, 22 Jun 2011 11:37:36 +0000

Leks, they’re called, gatherings of males of certain animal species for competitive mating displays.

But not every lek’s members are competitors, scientists have learned. Some–birds called wire-tailed manakins, residents of tropical forests in the Americas–are cooperators as well as competitors.

Image right: Male wire-tailed manakin with adult plumage at age three. Click photos to enlarge. (Photo by Brandt Ryder)

“Male vertebrates often form reproductive coalitions to gain access to or to defend females,” says Brandt Ryder at the Smithsonian Conservation Biology Institute in Washington, D.C., “and in most contexts they compete for those females.”

Wire-tailed manakins, however, are different in that they cooperate, forming alliances for a common cause.

Wire-tailed manakins coordinate their courtship displays. “These displays, and the resulting leks formed,” says Ryder, “are a rare example of male cooperation within a lek social system.”

Image left: A wire-tailed manakin’s bright plumage is derived from pigments in the fruits it eats. (Photo by Brandt Ryder)

This cooperative behavior appears to have evolved twice in the manakin family–in the wire-tailed manakin group, and in another group known as blue-backed manakins, which live in the same tropical forests.

Ryder, John Blake of the University of Florida, Patricia Parker of the University of Missouri-St. Louis and Bette Loiselle of the University of Florida recently published results of a long-term study of manakin leks in the journal Behavioral Ecology.

Image right: Wire-tailed manakin nests are held together with spider webs and fine plant rootlets. (Photo by Brandt Ryder)

Females have large territories, on which they feed socially with other birds of their species. Males spend as much as 90 percent of their time at leks, where they display in elaborate courtship rituals, including using their wing feathers to make buzzing and snapping sounds.

The biologists found that regardless of how manakin leks are formed, they serve several functions: increasing male reproductive success, providing access to otherwise unavailable reproductive opportunities, establishing dominance hierarchies and facilitating new complex social behaviors.

Image left: Female wire-tailed manakins are a drab green, which helps conceal their nest locations. (Photo by John Blake)

“These display coalitions have long been of interest to scientists from an evolutionary standpoint,” says Loiselle, “because of the paradox of apparent cooperative behavior in a situation with intense competition.”

The Pipridae

Manakins are a family, the Pipridae, of unique small passerine birds; the Pipridae contains about 60 species, all living in the tropics.

The name “manakin” comes from the Middle Dutch mannekijn, or “little man.”

Image left: Five-day-old wire-tailed manakin nestlings with bands placed on them as part of the study. (Photo by Brandt Ryder)

Manakins are found from southern Mexico to northern Argentina, Paraguay, and southern Brazil, and on Trinidad and Tobago.

They’re almost exclusively birds of the forests and woodlands. Most live in humid tropical lowlands, with a few in dry forests, river forests, and the subtropical Andes.

The birds feed in the forest understory on small fruits, including berries, and to some degree, on insects.

Since they take fruit in flight–similar to how other birds snatch insects from the air–manakins are believed to have evolved from insect-eating birds.

Loiselle, Ryder and colleagues are conducting a long-term study of wire-tailed manakins at Tiputini Biodiversity Station. Tiputini is located adjacent to the Yasuni Biosphere Reserve in Ecuador.

The scientists locate leks of wire-tailed manakins by searching for and mapping locations of “singing” male manakins along transects in study plots.

The number of territorial males per lek ranges from 4-to-12.

Image left: A male wire-tailed manakin displays his striking plumage against the dense rainforest understory. (Photo by Brandt Ryder)

Leks are found in seasonally flooded forests, as well as on “terra firme.” The understory vegetation at the leks varies from open to closed, many covered by old tree falls and vine tangles. Most leks are in low-elevation flat areas near streams.

Gatherings of manakins may have much to tell us about not only tropical birds, but about leks of other species, such as the sharp-tailed grouse of Canadian and U.S. prairies.

Many lekking birds are threatened by habitat loss, whether in prairie or forest.

By knowing how–and where–manakins flourish, says Ryder, “we can learn which areas of the tropical forest need further conservation measures.”

–Source: National Science Foundation, by Cheryl Dybas

Green-headed Tanager (Tangara seledon) of east-central South America

John Barrat — Tue, 14 Jun 2011 17:36:07 +0000

A description and photos of the green-headed tanager (Tangara seledon), a bird native to east-central South America, can be found in the Species of the Day Archive of the Encyclopedia of Life. This tanager is one of several extravagantly multicolored tanagers found in one or another part of eastern Brazil. The Encyclopedia of Life is an unprecedented effort to gather and share scientific knowledge about all living things in a single online resource. EOL is a sweeping global effort to gather and share the vast wealth of information on every creature—animals, plants and microorganisms—and make it available as a web-based resource. Click eol.org to learn more. (Photo by Dario Sanches)