Thousands of kilometers north – migratory birds and a shifting world

30 April 2014 by Liz O'Connell, posted in Migration

White-Crowned Sparrow in Denali National Park & Preserve, Alaska / Image Alex Vanderstuyf, National Park Service (Creative Commons Attribution 2.0 Generic license)

White-Crowned Sparrow in Denali National Park & Preserve, Alaska / Image Alex Vanderstuyf, National Park Service (Creative Commons Attribution 2.0 Generic license)

Laura Nielsen for Frontier Scientists

The Arctic is blanketed in snow for 9 to 10 months of the year. Then in May or June, with the Sun shining long overhead, snow melt comes sudden. Mathew Sturm, professor of Geophysics, University of Alaska, Geophysics Institute says the world of the Arctic can go from “White to dark in a space of a week.”

“The extent of it is so vast, you can consider millions of square kilometers right now are in the process of turning from their winter cover to their summer in the space of a very very very few days.” “It’s utterly astounding: the speed in which this very very dramatic change in the landscape happens. … The longest we have ever seen it take at Imnavait is about 2 weeks and the shortest about 6 days.” ~Sturm

Rick Tomen, climate science and service manager for the National Weather Service, Alaska region, talked about the unusual 2013 Alaskan spring, and how it impacted migratory bird species.

”Across much of mainland Alaska... the middle part of spring from late March into mid-April was unusually cold. In interior Alaska it was the coldest spring since 1924. In South Central, not quite anomalous but certainly the coldest spring in decades.” “On the other hand across most of the Western United States on up through British Colombia and even into Southeast Alaska temperatures were near to above normal during the springtime.”

“Many bird species that come to Alaska for the summer kind of got stopped in their tracks and media report[ed] lots of birds congregating in the Southeast of the interior because father north and west there just was no open water yet, no melting of lakes and snow cover.” “Across mainland Alaska, about the 20th of May the pattern finally broke and as often happens in these kind of situations, kind of went to instant summer with temperatures of 80 in the interior and even 70’s in South Central.” ~Tomen

In the spring of 2013 Marilyn Romanovsky, an adjunct professor in the department of Neural Biology, Physiology and Behavior at the University of California, Davis, was on-site in the remote foothills of the Brooks Range, North Slope, Alaska.

“In May when we came [to Toolik Field Station], the snow and ice was incredible, it covered everything. You couldn’t tell the depth of snow; the tall 7 foot willows looked like they were just little seedlings.” “You can read about these conditions, you can look at pictures but there is nothing like the experience itself.” ~Romanovsky

She describes the snow-bound conditions, and how birds were getting stockpiled along the Alaska Canadian border. Eventually the birds did make their way through the snowy passes.

“We saw huge flocks of ducks and geese come in and just sit on locations where they were waiting to breed. Sitting on the ice for weeks, and not doing anything.” “Small song birds, when they did come in, …it was like winter for them, it was still migratory conditions but it wasn’t anywhere near breeding. They just held out. They fed on grass seedlings. They would crawl up these stems, and nibble” –”Manage eating the tops of dried seed heads to survive.” “They are just incredible in terms of surviving and being able to withstand harsh conditions.” ~Romanovsky

Chestnut-Collared Longspur landing in Canada / Image Wildlife Conservation Society via U.S. Fish & Wildlife Service (Creative Commons Attribution 2.0 Generic license)

Chestnut-Collared Longspur landing in Canada / Image Wildlife Conservation Society via U.S. Fish & Wildlife Service (Creative Commons Attribution 2.0 Generic license)

Even once the snow has cleared enough for migratory birds to nest, they still face challenges like unpredictable weather and spring storms. Associate professor at the University of Edinburgh Dr. Simone Meddle studies how songbirds have adapted their physiology to Arctic weather.

”Yesterday I was running around the tundra catching birds in a T-shirt and today I woke up with the tundra being completely covered in snow. It’s ok for me because I can put on more clothes and I’ve got food at Toolik camp. But what do these birds do when the weather suddenly turns bad? And in the Alaska tundra, this happens quite often. It is predictably unpredictable.” …. “It’s fascinating to understand how these birds manage to cope with days like today, when all their food is covered up and it’s cold.” ~Meddle

Alaska hosts birds from all over the world. Over 200 bird species have been recorded in one corner of Alaska in the Arctic National Wildlife Refuge. Many birds – species which over-winter in warmer climes – migrate to Alaska every warm season to breed.

Migration Flyways / U.S. Fish and Wildlife Service

Migration Flyways / U.S. Fish and Wildlife Service

They undergo a challenging task. Migration calls for high energy expenditure, as well as an intermixture of instinct, skill and cognitive ability. Once the birds arrive they face a ticking clock. They must court, breed and form pair bonds, build a nest, lay and incubate eggs, hunt, feed their hatchlings, then gain enough fuel to make the long distance return flight.

All this occurs during the very brief window of Arctic summer.

Jesse Krause, PhD student at the University of California Davis, is part of his university’s Birds and Seasonality project. Part of what Team Bird is studying is how global climate change impacts the cyclical events that happen every year in the Arctic (i.e. snow melt, plant growth, and insect emergence) and how those changes are affecting Arctic-breeding birds.

“Their migration is triggered [for the most part by] an increase in day length or photo period. So there is no way for them to adjust their departure date. Earlier in the season there are other cues that basically fine tune their departure, such as social cues and local weather cues and some things like this. But photo period is the major driver for activating the axis that can control both reproduction and migration. So if spring does come earlier there is a potential mismatch between resources that are available and when the birds need to utilize those resources to feed their offspring.”

“In Europe in certain species like the Pied Flycatchers where there is this big mismatch they are seeing as much as a 90% reduction in populations in these area. So it seems to be very localized. In some regions there is a mismatch but in other regions the timing is still in sync; those populations are still doing fine. Our project was funded to investigate ... whether or not this is occurring in the Alaskan Arctic.” ~Krause

Smith’s Longspurs winter in the South Central Plains states, then fly north, arriving at their destination in northern Alaska during the first week of June. For songbirds like the Smith’s Longspurs, Lapland Longspurs or White Crowned Sparrows, nest building takes a few days at most. Then the birds lay 4 to 5 eggs over 4 to 5 days. Incubation averages 12 to 14 days, and then nestlings remain in the nest for at least 9 days before they are ready to begin hesitant flight. Young fledglings will travel and feed locally in small groups watched over by adult males before they are ready to set off on a long migration south.

Dr. John Wingfield, University of California Davis professor of Neurobiology, Physiology and Behavior, talks about the Smith’s Longspurs patterns witnessed by the Birds and Seasonality project in 2013.

“On June 5th, the first males arrived ... The females arrived yesterday on June 8th. They arrived in the morning, we witnessed several courtship displays and by noon they were building nests.” “They are one of the last small birds to arrive in the Arctic to breed, and they get right to it. It’s quite remarkable, there is no waste of time whatsoever.”

“It takes a certain amount of time to produce eggs. They have to be incubated usually about 14 days ... before they hatch. Then it takes about the same amount of time to raise the young. These birds have telescoped everything into the shortest time possible because the breeding season up here is only 5 weeks. And then they also need to molt and get out before the first winter storms start in August.” “What would take similar sized birds about two months in temperate latitudes, they have compressed into 4-5 weeks up here.” ~Wingfield

To be successful, migratory birds must attain synchrony. They must arrive in the Arctic when there is enough liquid water and available food to support them and when their necessary nesting habitat is available (not buried in snow). Once their young hatch, they must be able to obtain plenty of food to feed them; nestlings need to be strong enough to fledge and fly on their own before winter nears again. Nestlings eat mainly arthropods (insects, spiders, or tiny crustaceans), protein rich food sources that help them achieve high growth rates. Parents bringing nestlings food make up to 30 trips per hour back and forth to the nest, and they have to bring plenty of food for hungry mouths. If the birds’ timing is off, their young will hatch too early or too late in the season to survive.

Ecological Regions of northern Alaska; Toolik Field Station is in the northern foothills of the Brooks Range / U.S. Fish and Wildlife Service

Ecological Regions of northern Alaska; Toolik Field Station is in the northern foothills of the Brooks Range / U.S. Fish and Wildlife Service

Jonathan Perez, a graduate student at the University of California Davis, works with John Wingfield. He witnessed an early spring melt in 2012, then a late one in 2013.

“The Arctic is so variable year to year. I mean by this time last year we had birds that had already laid eggs, and this year they are barely building nests at this point. Year to year variability is so great that you really need a long term data set, 20 plus years to really be able to say anything about change because if you just happen to get that one odd year, it’s very hard to say anything concrete.“ “Something that we are interested in is these odd years, and comparing different types of years to each other, which is why this year is so exciting – a late snow melt … Hopefully at the end of this season we can compare how the reproductive output compares with an early snow melt verses a late snow melt and how does that impact their ability to raise offspring.” ~Perez

White Crowned Sparrows nest in shrubs, while Lapland Longspurs nest atop the open tundra. Research into such diversified organisms helps paint a picture. What happens when permafrost across the Arctic thaws, releasing ancient organic matter, carbon, and nutrients? What happens as plant biomes shift their ranges north, and shrubs like dwarf birch overtake the lichen and moss of the tundra?

Ashly Asmus, graduate research assistant at the University of Texas at Arlington, talks about the importance of plants and bugs.

”One thing we are interested in is: as the permafrost thaws, one type of plant – the dwarf birch – is being favored over all of the other types of plants and is crowding out a lot of other plant diversity. And along with that we are seeing a change in the community composition of insects. So an entirely different community of insects is associated with these shrubs that we don’t see in the regular open tundra that is more dominant. Or that used to be more dominant before climate change.”

As insect populations and their emergence times alter due to changing vegetation and temperature regimes and tiny sea creatures are impacted by warmer and more acidic ocean water, how will birds react? How do shorebirds adjust when the coastal wetlands they use for staging (resting and feeding) and nesting become inundated with saltwater?

We are already seeing responses among bird populations. 177 out of of 305 bird species tracked in North America now overwinter with population centers an average of 35 miles [56 kilometers] further north than past records. Some species’ winter centers of abundance have shifted northward more than 100 miles [160 kilometers].

White-Crowned Sparrow (Zonotrichia leucophrys) / Image by Tom, Flickr profile 'Seabamirum' (Creative Commons Attribution 2.0 Generic license)

White-Crowned Sparrow (Zonotrichia leucophrys) / Image by Tom, Flickr profile 'Seabamirum' (Creative Commons Attribution 2.0 Generic license)

Jesse Krause talks about the extreme weather events which are projected to increase as the Earth warms.

“Another prediction about global climate change is that spring snow storms may be more intense or more frequent which may have been evident this spring when we had basically snow falling into late May and it was really delaying migrations. That is another consequence of climate change: these more intense spring snow storms, and how will that affect the birds because now we’re essentially compressing the summer (potentially).” ~Krause

Migration isn’t easy; it means calling more than one place home. Breeding grounds, stop-over sites used along migration pathways, and wintering grounds – all provide essential habitat to migratory birds. Somewhere the birds call home, you can be sure that conditions will change. Even the best times for migration are changing, but no one can pencil in updates to avian calendars.

Marilyn Romanovsky explains why Team Bird is so focused on migratory populations.

“Migration is one of the major biological functions of the annual cycle.” “Birds that migrate are confronting a variety of different habitats.” ... “If you are going long distances, you are reliant on each habitat as you enter and leave it.” “Any one habit, whether you are a resident or you are a migrant, of course is ongoing lots of change.”

“This year conditions were pretty rough; other years they might be more advanced so the resources that the bird needs, the refugia, the food, might be a little advanced or a little slower. So in many ways, it’s great if the populations can keep pace, but it’s hard to keep pace when you are wintering thousands of kilometers south and coming to an area where you don’t know what its conditions are going to be from year to year.”

“They’ve come into areas, they’ve flown thousands of miles, they’ve got more to go. They are under a time budget. If those locations are somehow disrupted, this can really affect the population in terms of increased mortality. We are seeing this with the Red Knot worldwide. And other migratory populations are shifting and showing huge mortality.”

“So in many ways the responses of long distant migrants are true indicators of the health of the planet.” ~Romanovsky

Red Knots forage amid horseshoe crabs at Mispillion Harbor in Delaware / Image Gregory Breese, U.S. Fish and Wildlife Service

Red Knots forage amid horseshoe crabs at Mispillion Harbor in Delaware / Image Gregory Breese, U.S. Fish and Wildlife Service

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References:

  • FrontierScientists interviews with the quoted scientists during their 2013 research season at Toolik Field Station
  • 'Arctic & Alpine, 2010 Report on Climate Change' The State of the Birds (2010)
    http://www.stateofthebirds.org/2010/habitats/arctic-alpine
  • 'Birds' Gates Of The Arctic National Park & Preserve, Alaska (April 6, 2014)
    http://www.nps.gov/gaar/naturescience/birds.htm
  • 'Climate Change and its Impacts' U.S. Fish & Wildlife Service, Arctic National wildlife Refuge, Alaska (December 29, 2009)
    http://www.fws.gov/alaska/nwr/arctic/ctclimatechange09.htm
  • 'Measuring and Forecasting the Response of Alaska’s Terrestrial Ecosystem to a Warming Climate' U.S. Geological Survey Fact Sheet, by John Pearce, Tony DeGange, Paul Flint, Tom Fondell, David Gustine, Leslie Holland-Bartels, Andrew Hope, Jerry Hupp, Josh Koch, Joel Schmutz, Sandra Talbot, David Ward, and Mary Whalen (December 26, 2012)
    http://pubs.usgs.gov/fs/2012/3144/
  • 'Shifting Skies: Migratory Birds in a Warming World' Doug Inkley, National Wildlife Federation (June 18, 2013)
    http://www.nwf.org/News-and-Magazines/Media-Center/Reports/Archive/2013/06-18-13-Migratory-Birds-in-a-Warming-World.aspx
  • 'Understanding the Science of Climate Change: Talking Points – Impacts to Alaska Boreal and Arctic' Natural Resource Report, National Park Service, U.S. Department of the Interior (July 2010)
    http://www.nps.gov/subjects/climatechange/upload/BorealarcticTalkingPoints.pdf

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