From opposite sides of the world with two closely related species of wader we are going to be treated to some really interesting migration information as they are tracked by satellite transmitters. We have seen on the one hand the long distance migrant Little Curlews make a marathon flight from Australia to Russia and we will now find out where Long-billed Curlews in North America spend their time. I'll let Heidi Ware of the Intermountain Bird Observatory introduce the project to you.
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Long-billed Curlew Numenius americanus. California, USA. December 2012. |
The Intermountain Bird Observatory (IBO) has been studying
Long-billed Curlews in Idaho, USA, since 2009. When the project began, our goal
was simply to help the Idaho Department of Fish and Game monitor a population
of curlews that were nesting in southwestern Idaho near the towns of Emmett and
Middleton. On our first day of surveys in 2009, the crew came across a dead
curlew in the middle of the road. It had been shot.
This was a bad omen for discoveries to come: after studying
the nesting success in this area, we soon realized that the entire population
was in trouble. We found that nesting success was much lower than it had been
in the past, and that the adult breeding population had declined by as much as
90% since studies in the late 1970’s. In just four years, we saw Long-billed
Curlew numbers drop from around 300 to less than 200 in the study area. So in
2012 IBO began looking for ways to help the birds breeding there.
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Long-billed Curlew chick Numenius americanus. Photo: Liz Urban. |
Throughout the western US, Long-billed Curlews face a
variety of threats on both breeding and wintering grounds. On their breeding
grounds, Long-billed Curlews face problems from human disturbance, habitat
changes, shooting, and changes in agricultural practices. On their wintering
grounds, curlews may face changes in water regimes based on agriculture or
drought, habitat loss, and human disturbance. We decided to use satellite
transmitters to learn more about their movements in Idaho and surrounding
states and determine when and where birds are facing threats.
The original goal of our tracking project was to determine
where Long-billed Curlews from the southwestern Idaho population spend their
time during the breeding season and where they go in the winter. We have
expanded that goal to encompass other breeding populations elsewhere in Idaho,
western Montana, and Wyoming to compare nest success and satellite data in
different geographical areas.
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Long-billed Curlew AX flying on hatch day. Photo: Liz Urban. |
If curlews from healthy populations winter in one area, and
birds from declining populations winter in another location, this may be a sign
that factors at a particular wintering location are causing their population
declines. If birds from both healthy and declining breeding populations
intermingle on their wintering grounds, this is more likely a sign that threats
on the breeding grounds are causing decreases in the number of adults.
Thanks to numerous partners and donations from our
supporters, we placed 4 PTT transmitters in 2013, added 11 transmitters in 2014,
and in 2015 we plan to deploy 19 more transmitters across the intermountain
west of the United States in seven different breeding populations. By studying
populations from areas where no previous transmitter work has been done, we
will be able to fill in a ‘gap’ between previous studies of Long-billed Curlews
in locations such as eastern Montana, northern Oregon, and northeastern Nevada.
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Long-billed Curlew AX with its satellite fitted. Photo: Heidi Ware. |
Follow along with us as we track our flock of curlews! Along
with attaching 19 transmitters this season, IBO’s graduate student Stephanie
Coates will be studying the reproductive success of curlews at six breeding
locations across the three states to determine what differences exist between
these populations during the breeding season. In particular, she’ll be
examining how differences in habitat type, predator communities, and human
disturbance affect nesting success.
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Long-billed Curlew Numenius americanus. California, USA. December 2012. Photo: Elis Simpson |
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