Prospects for Kirtland's warbler remain uncertain

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Capital News Service
LANSING — The population of one of the Great Lakes region’s rarest birds – the Kirtland’s warbler – has dropped for the first time since 2002.

Credit: U.S. Fish and Wildlife Services

The latest unofficial population figure collected by the U.S. Fish and Wildlife Service data shows 1,758 males. Last year the count was 1,826.
The 5-inch long, gray-and-yellow bird lives only in parts of Michigan, Wisconsin and Ontario. Ninety-seven percent of those counted last year live in the northern Lower Peninsula. Only males are audible and easily counted during the census season. Experts estimate that there is most likely one female for every male counted.
But the drop in numbers isn’t considered serious, according to Chris Mensing, a fish and wildlife biologist with the federal agency.
“The decline in our count does not appear to be that significant. We know that the census is more an estimate than an exact count, so going down a few birds isn’t something we are immediately concerned about,” said Mensing, who has worked with Kirtland’s warblers for 11 years.
No matter the exact number in the wild, these rare birds face significant challenges – like long-term funding and the consequences of climate change.
Caleb Putnam, coordinator of the Audubon Society’s Michigan Important Bird Areas, said, “This is a very rare species, the rarest warbler in North America. There are around 4,000 individuals in the entire world and almost all of them nest in Michigan.”
Rarity gives the bird worldwide recognition. In 2009, 35 international visitors  from countries like Australia, Sweden and the United Kingdom went on guided tours in Michigan’s Huron-Manistee National Forest to catch a glimpse.
“A lot of people come from all over to see the Kirtland’s,” said Kim Piccolo, a wildlife biologist at the Mio Ranger District of Huron-Manistee National Forest.
The bird’s recorded population was the lowest in 1974 and 1987, when scientists counted 167 males. The average annual count since 1951 has been 602.
Experts attribute the low numbers to habitat loss and the brown-headed cowbird,  a parasitic bird that lays its own eggs in the warbler’s nest. In 1972, cowbird control began, and a recovery plan to protect habitat and monitor the species began four years later.
Current numbers are well above the original conservation goal of maintaining 1,000 pairs for five years. Each year since 2001 experts counted 1,000 males indicating the presence of 1,000 females to match.
But that doesn’t mean it’s in the clear yet. And it may never be.
Mensing said, “We’re definitely not out of the woods. The second we stop any of that bird management that bird population is going to decrease.”
According to Mensing, some species, like the wolf or bald eagle, have good outlooks for survival once they reach high populations.
But not the warbler.
That’s because the warbler is “conservation-reliant,” meaning it can’t survive without consistent management efforts that may be required into the unforeseeable future.
Its conservation-reliance stems from its needs for a specific habitat because it can live only in sandy areas with jack pines between the ages of 5 and 20.
That habitat requirement makes it unable to adapt easily.
Putnam said, “You can think of these birds as stuck in these islands of habitats that are very limiting.”
Management-reliant species peck at federal funds and time, leaving less money for other species, and it’s unclear whether that high level of management is sustainable in the long-term.
Mensing said, “From our standpoint, we want to, we need to protect these species. We need too look at how we can do this forever.”
To create a sustainable long-term management plan for the warbler, the Fish and Wildlife Service paired up with the National Fish and Wildlife Foundation to raise money for an endowment.
Using private money would not only guarantee the warbler long-term management but free federal money to aid other species.
If done correctly this endowment-model could also be used for the management of other species, Mensing said. “If we don’t do it right we’re back at square one. And if we do, do it right it could benefit the Kirtland’s warbler and many other species.”
At the same time, the unknown consequences of climate change loom, according to Putnam.
“The Union of Concerned Scientists is predicting in Michigan…rising temperatures in winter and in summer, by the end of the century as high as 10 degrees Fahrenheit,” he said. The temperature shift also may create dryer habitats for birds due to increased evaporation.
An Audubon Society report last year show that North American birds reacted to climate shifts that in the last 40 years by moving migration patterns further northward and inland. But the same factor that makes the warbler conservation-reliant – its specific habitat needs – may make such migration change impossible.
“When you have a species that is rare and is very stuck in that habitat type, if the climate conditions change such that it makes them want to shift north, there may not be anywhere to go,” Putnam said.
Alice Rossignol writes for Great Lakes Echo.
© 2010, Capital News Service, Michigan State University School of Journalism. Not to be reproduced without permission.

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