Project Overview:

Our research team studies how climate change affects migratory songbirds at the Hubbard Brook Experimental Forest in New Hampshire’s White Mountains, where we have monitored bird populations since 1969. To identify factors that regulate bird populations requires information about how well birds reproduce each season and how well they survive from one year to the next. In 1986, we initiated an intensive population demographic study of the black-throated blue warbler. We have studied this population continuously for nearly 40 years.

Since the Hubbard Brook Experimental Forest was established in 1955, summer temperature has increased by an unprecedented 2 degrees Celsius resulting in earlier leaf out, occurring 1.2 days earlier each decade, and affecting the availability of caterpillar prey for migratory songbirds. By the end of the century, summer temperatures are expected to increase by an additional 2 to 5 degrees Celsius. These patterns and forecasted climate change have led our research team to focus on the behavioral responses of migratory birds to climate change and the demographic effects of those responses.

Our research team investigates the choices black-throated blue warblers make in response to climate change, which could directly impact their population dynamics.

• when to arrive to the breeding grounds (timing of arrival)
• where to breed (territory selection)
• when to breed (breeding phenology)
• how much effort to invest in mating and parental care (reproductive effort)
• how many broods to raise in a season (double-brooding)
• when to molt (molt-breeding overlap)
• when to depart to the wintering grounds (timing of departure)
• if breeding sites change between years (site fidelity)

Our goals are to determine whether observed behavioral and demographic adjustments of individuals will be sufficient to compensate for climate-induced changes in habitat quality. We combine the power of large-scale field experiments across an 600-m environmental gradient with long-term time series data to address our research questions.