The following item is an interesting read on wildlife research. I'm
not sure that the research findings would apply to cassowaries, but I
suspect that they would apply to a number of Australian species ...
http://news-service.stanford.edu/pr/2007/pr-birds-052307.html
Some forest birds can survive in agricultural countryside with limited
habitat conservation, study finds
May 21, 2007
Some tropical forest birds can survive alongside humans if given a
helping hand, according to a recent study by Cagan H. Sekercioglu,
senior scientist at the Stanford University Center for Conservation
Biology.
The results, published in the April 2007 issue of the journal
Conservation Biology , could influence the way countries approach
endangered species protection in agricultural areas, Sekercioglu said.
"Even modest restoration efforts can increase their land cover and help
some forest birds more than you would think," he said.
The study was conducted in Costa Rica at the Las Cruces Biological
Station of the Organization for Tropical Studies, where most of the
forested terrain has been converted to open coffee plantations or
pasture—unfavorable habitats for birds, according to Sekercioglu. In
previous studies, researchers had identified nearly 200 bird species in
coffee plantations by simply capturing or observing them there. "If you
do that, you might think, 'Well, these birds are doing fine in coffee
plantations," Sekercioglu said.
However, he felt that simply seeing the birds in coffee plantations was
not sufficient evidence to conclude that they had adapted to life
outside their native habitat. Sekercioglu wanted to follow the birds
more closely. He and his team set up a comprehensive bird-banding and
radio-tracking system to monitor the birds' positions throughout the
day.
First, they hung mist nets in various places in the coffee plantations
to catch a large sample size of birds of three particular species.
Then, they tagged each bird with two colored leg bands and an aluminum
ring with an identification number. Using false-eyelash glue, they
attached a radio-transmitter with a battery life of one-to-three
months. The team tagged and tracked a total of 156 birds during the
study.
"We had a Pathfinder packed with 10 people and gear," he recalled. "A
couple times we had people hanging onto the outside. It's lot of fun."
The researchers encountered a few surprises during the study. One
assistant tracked a slow-moving radio signal to the forest floor, a
strange occurrence since most of the bird species prefer tree branches.
As the signal became louder, the researcher suddenly realized it was
coming from a bushmaster, the deadliest snake in Latin America. The
15-foot snake had eaten both the bird and its radio. "It just started
slithering away and the signal faded," Sekercioglu said.
Every day, each team member would be assigned to track from one to six
birds. They generally worked from dawn to dusk. "We start before the
birds are awake and moving," Sekercioglu said. "We leave the station at
4:30 a.m."
The researchers recorded every bird's information in a database,
including its species, band number and the number of daily sightings.
The team tried to record at least 50 to 100 sightings for each of the
156 birds scattered across a period of at least 10 days, Sekercioglu
said.
After eight months of tracking over two seasons, the team concluded
that many tropical forest birds tend to avoid coffee plantations, even
though they were frequently observed there by researchers in previous
studies. "When you radio-track birds, you realize many go through
coffee because they have to," Sekercioglu said. "Seeing them in coffee
does not necessarily mean they like it there."
Because the coffee plant is not native to Costa Rica, local birds have
not evolved to eat the fruit or to live among the open fields of the
plantations, he said. "Although we caught all these birds in coffee,
most of them prefer remnant forest fragments, individual trees and
trees along rivers, which are called riparian corridors." He added,
"Most birds don't like to eat the coffee fruit. Caffeine evolved as a
pesticide to keep pests away."
The team compared percentages of land-cover type in the area to the
birds' preferred locations. "Remnant trees—individual trees—only
covered 1.4 percent of the landscape, but some of the birds spent 25 to
30 percent of their time in these few trees," Sekercioglu explained.
Similarly, some birds spent up to half their time in riparian
corridors, which cover only 4.6 percent of the area.
"These small patches of trees are critical for these native birds,"
Sekercioglu said.
Sekercioglu is optimistic about the implications of his findings for
endangered bird species. "Even modest restoration efforts to increase
tree land cover can help these birds more than you would think," he
said.
Furthermore, the research demonstrated the ability of some tropical
forest birds to survive in human-dominated agricultural countryside.
"That's good news," Sekercioglu said. "Even though they didn't spend a
lot of time in coffee plants themselves, they did fine in a
coffee-dominated landscape, as long as there were some trees around."
These findings suggest that humans and birds may be able to
successfully coexist if farmers leave small reserves of forest,
riparian strips or single trees interspersed throughout agricultural
land, Sekercioglu said. "Even though we would like to have big national
parks with a lot of forest, sometimes when you can't have that, when
you have to have agriculture, it's really important to have these
reserves of native trees and native forests, which can support large
numbers of native birds and other organisms," he added.
Sekercioglu's recommendations are helping to shape a Las Cruces project
encouraging local people to plant native trees around their farms and
villages, and Sekercioglu and his colleagues are planning a workshop at
Las Cruces on restoration ecology. "It's starting to have an impact, so
that's exciting," he said.
In addition to banding and tracking birds, the research team monitored
over 300 nests. Also, they have collected more than 10,000 feather
samples to determine the protein content in birds' diets and have taken
nearly 2,000 blood samples for genetic analyses and to study avian
malaria, Sekercioglu said.
"The more we learn, the more we realize we don't know," he said.
"That's why you need a multi-pronged approach to look at birds' habits
from every level."
Walter Loewenstern, the Koret Foundation, the Moore Family Foundation,
the Christensen Fund, the National Geographic Society and the Wildlife
Conservation Society provided funding for the study published in
Conservation Biology .
Chelsea Anne Young is an intern at Stanford News Service.
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