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.

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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.

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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

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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

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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

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But Charles Bendire did. And thanks to a research project that is the next best thing to time travel, DeJong is measuring the duck eggs in a number of museum collections, such as those at the Smithsonian’s National Museum of Natural History in Washington, D.C.  Bendire (1836-1897), an ornithologist and the Smithsonian’s first honorary curator of the discipline known as oology, or the study of birds’ eggs. When her project is done, DeJong will have assembled and analyzed a metrics database on perhaps 60,000 duck eggs representing at least 40 species and subspecies of ducks found in North America.

Image right: South Dakota State University researcher Julie DeJong measures duck eggs in university and museum collections for clues about how duck species may have responded to climate patterns and long-term climate change.

What she learns could ultimately add new knowledge about how waterfowl respond to climate cycles and long-term climate change.

DeJong is a Ph.D. student in South Dakota State University’s Department of Wildlife and Fisheries Sciences. Part of her work involves logging current measurements of duck eggs that cooperating researchers are gathering for her in the field, as well as recent measurements from studies in the past few years. But DeJong is also visiting museums across the U.S. and Canada to measure duck eggs collected by naturalists up to 150 years ago to build a database of how the dimensions of eggs have changed, if they have changed, over past decades.

Image right: Charles Bendire, an ornithologist who donated many eggs to the Smithsonian.

“What we’re trying to do with this project is to see, through different drought cycles and heavily wet cycles, if the size of the eggs from these ducks will change,” DeJong says. “The reason that they might change in size is due to changes in the nutrient levels from foods such as invertebrates that are available during breeding. If, say, the Prairie Pothole Region is completely dried up due to drought for several years in a row, those ducks are going to experience a drop in the nutrients they’re used to getting…. Our hypothesis is that their eggs will be smaller then.”

“It is like time travel, because there’s no way I could go back 150 years and collect that kind of data,” DeJong said. “There is so much information sitting there in these museums that people forget about. When people these days plan a research project, they’re starting today and going into the future. They don’t usually have the opportunity to look backward.”

Looking backward is already revealing some surprises. While it’s too soon to draw firm conclusions, DeJong noted that her preliminary data does suggest that a few species, such as the Lesser Scaup, appear to be producing smaller eggs during the last 40 to 50 years.

DeJong plans to plot the coordinates of the egg collections on a map of North America using geographic information system technology, and she’ll overlay that map with new layers of information about ecological region and climate patterns through the years. Ultimately she’ll be able to determine whether changes in duck egg size appear for specific species or ecological regions or time periods.

Since duck egg collectors weren’t spread out systematically over time or geography, there are gaps that pose challenges for statistical analysis. One way DeJong tries to deal with that is by simply visiting more museums and mapping the data from more eggs. She’s indebted to 19^th century naturalists—the Smithsonian’s Bendire and others like him—for much of her data.

“These early bird egg collectors, largely known as ‘oologists,’ were a breed all their own. They went out and trekked into swamps, prairies and woodlands all over the United States and Canada and the far reaches of Alaska and collected these eggs, some of them just for their own enjoyment, some for commercial sale, and some of them to document what was there,” DeJong says.

“Early oologists were the first birders in North America, yet most of them were not scientists per se, but an assortment of doctors, farmers, hunters, and nature enthusiasts. Our early information on the breeding season, habitat use, and physical descriptions of the breeding adults and their nests and eggs of hundreds of North American birds came from oologists,” DeJong said. “By collecting the eggs and other collateral data, they were not only collecting beautiful objects to put in a cabinet drawer, they were also documenting the natural history and breeding history of the birds, which can be used by scientists today and in the future. I hope my research stimulates thought about the possible uses of these egg collections and of other kinds of specimen collections in museums around the world. By making use of these collections, we pay tribute to these naturalists for their hard work, perseverance and love of nature.–Source: South Dakota State University

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Image left: male American redstart

Many of the bird species that breed in the temperate forests, marshes and backyards of North America spend the winter months in the tropics of the Caribbean, and Central and South America. Insects are the primary food for many birds during the winter, and rainfall largely determines the amount of insects available. Climactic warming, however, is causing declining and more variable rainfall cycles in many areas, affecting the availability of insects and delaying when birds leave for their northern breeding grounds. To examine this, the Smithsonian scientists focused on American redstarts (Setophaga ruticilla), a member of the warbler family, at a non-breeding site in Jamaica where they conduct long-term studies.

Image right: female American redstart

“American redstarts were a perfect species for this study since they defend exclusive territories throughout the non-breeding period until they depart for spring migration and most return back to the same territory the following year,” said Pete Marra, research ecologist at the Smithsonian Conservation Biology Institute’s Migratory Bird Center. “These behaviors made it relatively easy to keep track of individual birds over multiple years and document changing spring departures. Each individual was fitted with a unique combination of colored leg bands.”

Precipitation in Jamaica is highly seasonal, with consistent rainfall from September to November and a pronounced dry season from January to March. The scientists observed the redstarts in their non-breeding territories for five years during the dry season. They paid special attention to the annual variation in dry season rainfall. The correlation between the amount of insects in a bird’s territory and the timing of its departure suggested to the team that annual variation in food availability was an important determining factor in the timing of spring migration. Had the redstarts relied on internal cues alone to schedule their spring departure, they would have all left their winter territories at the same time each year.

Image left: A drying mangrove swamp.

“Our results support the idea that environmental conditions on tropical non-breeding areas can influence the departure time for spring migration,” said Colin Studds, a postdoctoral fellow at the Smithsonian Conservation Biology Institute’s Migratory Bird Center and lead author of the study. “We found that the same birds changed their spring departure from one year to the next in relation to the amount of rainfall and food in March.”

During the past 16 years, the dry season in Jamaica has become both increasingly severe and unpredictable, leading to an 11 percent drop in total rainfall during the three-month annual drought. Making the future even more dire, climate models predict not only increased warming on temperate breeding areas but also continued drying in the Caribbean.

A critical question for the scientists is whether this variation in the onset of spring migration carries consequences for the birds. Delaying departure could be beneficial if food resources are low and the individual has not yet stored enough energy to migrate. However, delaying departure could affect arrival time to its breeding territory and result in less time to successfully reproduce. “Because American redstarts return to the same site to breed each year, arriving later may make it harder for them remain to remain in synch with their breeding cycle,” Studds said.--Johnny Gibbons

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Urban areas cover more than 100 million acres within the continental the United States and are spreading, with an increase of 48 percent from 1982 to 2003. Although urbanization affects wildlife, ecologists know relatively little about its effect on the productivity and survival of breeding birds. To learn more, a team of scientists at the Smithsonian’s Migratory Bird Center studied the gray catbird (Dumatella carolinensis) in three suburban Maryland areas outside of Washington, D.C.—Bethesda, Opal Daniels and Spring Park.

Images top and bottom: gray catbird–Dumatella carolinensis (Photos by Johnny N. Dell, Bugwood.org). Middle image: a domestic cat--Felis catus (Photo by Terry Spivey, USDA Forest Service, Bugwood.org)

The team found that factors such as brood size, sex or hatching date played no significant role in a fledgling’s survival. The main determining factor was predation, which accounted for 79 percent of juvenile catbird deaths within the team’s three suburban study sites. Nearly half (47 percent) of the deaths were attributed to domestic cats in Opal Daniels and Spring Park. The deaths were either witnessed by the scientists or determined to be cat-related by the condition of the fledgling’s remains, such as a decapitated bird with the body left uneaten—defining characters of a cat kill. Domestic cats were never detected during predator surveys in the third suburban study site, Bethesda.

“The predation by cats on fledgling catbirds made these suburban areas ecological traps for nesting birds,” said Peter Marra, Smithsonian research scientist. “The habitats looked suitable for breeding birds with lots of shrubs for nesting and areas for feeding, but the presence of cats, a relatively recent phenomenon, isn’t a cue birds use when deciding where to nest.”

Technology made tracking the fledgling catbirds possible. The team fitted 69 fledglings with small radio-transmitters. Scientists tracked each individual and recorded its location every other day until they died or left the study area. This detailed type of field research was very limited until recently when transmitters were made small and light enough for songbirds.

Tracking the fledglings revealed that the vast majority of young catbird deaths occurred in the first week after a bird fledged from the nest. This was not surprising to the team, given that fledglings beg loudly for food and are not yet alert to predators—making fledglings in suburban environments particularly prone to vis

ual predators such as domestic cats. Domestic cats in suburban areas that are allowed outside spend the majority of time in their own or adjacent yards, so they are likely able to intensely monitor, locate and hunt inexperienced juvenile birds. Rats and crows were also found to be significant suburban threats to fledgling catbirds.

“Cats are natural predators of not just birds but also mammals—killing is what they are meant to do and it’s not their fault,” said Marra. “Removing both pet and feral cats from outdoor environments is a simple solution to a major problem impacting our native wildlife.”

The scientists’ findings were published in the Journal of Ornithology, January 2011 –Johnny Gibbons

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