Breeding flexibility helps migratory songbirds adjust to climate warming

November 12, 2015, Dartmouth College
A Dartmouth-led study finds that the black-throated blue warbler, a common migratory songbird, has a natural flexibility in its breeding time that has helped stave off the impact of climate warming on its food availability, at least for now. Credit: Trisha Shears

Phenological mismatches, or a mistiming between creatures and the prey and plants they eat, is one of the biggest known impacts of climate change on ecological systems. But a Dartmouth-led study finds that one common migratory songbird has a natural flexibility in its breeding time that has helped stave off mismatches, at least for now.

The results suggest this flexibility provides a buffer against for the black-throated blue warbler in eastern North America and potentially for other migratory forest birds in temperate zones, but such resilience probably has limits.

The study appears in the journal Oikos. The research included scientists from Dartmouth College, Norwegian Institute of Nature Research, Smithsonian Conservation Biology Institute and Wellesley College.

"Understanding the effects of climate warming on is critical for the conservation of forest bird species and their habitats," says lead author Nina Lany, who conducted the study as part of her doctoral degree at Dartmouth and is now a postdoctoral researcher at Michigan State University.

The researchers studied the causes and consequences of year-to-year variation over 25 years in the breeding time of the black-throated blue warbler in the Hubbard Brook Experimental Forest in the White Mountains of New Hampshire. They compared its breeding time and success to the timing of spring leaf-out and the availability of the leaf-feeding caterpillars eaten by birds. The timing of spring leaf-out varies by as much as a month from year to year in hardwood forests of the northeastern United States. This variability poses a challenge to that migrate from the tropics and then time their breeding to maximize reproductive success.

The study's results show that black-throated blue warblers are remarkably adept in timing their nesting relative to spring leaf-out of trees. In years when leaf expansion is completed 10 days earlier than usual, the birds tend to lay their first egg about six days earlier than usual. The birds do not match the changes in spring leaf-out exactly. Rather, they shift by the amount needed to maximize their breeding success —on average, birds produced fewer offspring in years when they nested earlier or later than the typical adjustment. The arrival time of these migratory birds in spring isn't very sensitive to the timing of budburst (only 1.6 days earlier than usual when budburst is 10 days earlier). At present, even in the earliest springs, birds have been returning in time to start breeding at the optimal time, but this could change as springs come much earlier.

Phenological mismatches between and the insects they eat can threaten species in a warming world. But in the temperate zone, ecosystems already have high natural variability in phenology and species that live there may be well adapted to this variability.

"Our studies documented flexibility in the timing of nesting by a migratory bird species that allows most breeding pairs to adjust the timing of nesting in spring to just the amount needed to maximize breeding success," says Lany. "Such flexibility, although clearly beneficial at present, might have limits that could be exceeded as warming continues."

Explore further: Earlier snowmelt prompting earlier breeding of Arctic birds

Related Stories

Earlier snowmelt prompting earlier breeding of Arctic birds

June 25, 2014

A new collaborative study that included the work of Wildlife Conservation Society (WCS) biologists has revealed that migratory birds that breed in Arctic Alaska are initiating nests earlier in the spring, and that snowmelt ...

Birds time breeding to hit 'peak caterpillar'

May 25, 2015

When oaks burst into life in spring populations of oak-leaf-eating caterpillars boom: this offers a food bonanza for caterpillar-munching birds looking to raise a family.

Environmental conditions may impact bird migration

May 14, 2014

Wind conditions during spring migration may be a predictor of apparent annual survival and the timing of breeding in yellow warblers, according to results published May 14, 2014, in the open access journal PLOS ONE by Anna ...

Broadleaf trees show reduced sensitivity to global warming

September 29, 2015

The sensitivity of leaf unfolding phenology to climate warming has significantly declined since 1980s, according to a study recently published in the journal Nature by an international collaboration of scientists. Earlier ...

Recommended for you

Archaeologists discover Incan tomb in Peru

February 16, 2019

Peruvian archaeologists discovered an Incan tomb in the north of the country where an elite member of the pre-Columbian empire was buried, one of the investigators announced Friday.

Where is the universe hiding its missing mass?

February 15, 2019

Astronomers have spent decades looking for something that sounds like it would be hard to miss: about a third of the "normal" matter in the Universe. New results from NASA's Chandra X-ray Observatory may have helped them ...

What rising seas mean for local economies

February 15, 2019

Impacts from climate change are not always easy to see. But for many local businesses in coastal communities across the United States, the evidence is right outside their doors—or in their parking lots.

The friendly extortioner takes it all

February 15, 2019

Cooperating with other people makes many things easier. However, competition is also a characteristic aspect of our society. In their struggle for contracts and positions, people have to be more successful than their competitors ...


Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.