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Exploring spatiotemporal variation in migration phenology

Temperature and Red-eyed Vireo arrival date by year

Allen Hurlbert and Zhongfei Liang recently used eBird data to publish a paper entitled “Spatiotemporal Variation in Avian Migration Phenology: Citizen Science Reveals Effects of Climate Change”, which appears in the journal PLoS One. Allen wanted to thank the eBird community, and provided the following overview of the article: “Your eBird observations continue to help shed light on fundamental questions regarding avian ecology and distribution. You’ve already seen the amazing animated occurrence maps that the Cornell Lab of Ornithology has developed. With former UNC undergrad Zhongfei Liang, I recently used eBird data for a slightly different purpose: we examined the extent to which birds have been shifting the timing of spring migration in response to year-to-year variation in spring temperature over the past 10 years and at sites throughout eastern North America. We found what many of you have undoubtedly observed yourselves–that many species, like the Red-eyed Vireo and Scarlet Tanager, are arriving earlier in warm years and later in cold years. Other species, however, such as the Barn Swallow and Eastern Wood-Pewee, do not seem to be as able to adapt to this variation in climate, and their populations may be suffering as a result.”

A number of previous studies have tackled this relationship between temperature and the timing of migration, but nearly all have been conducted at just one or a handful of locations–a bird observatory, or long-term banding station, for example. While these studies have the advantage of much longer time series, what they lack and what is a major strength of the eBird dataset, is geographic breadth. This breadth has allowed us to identify, for example, that birds breeding in the Southeast appear to be more sensitive to temperature, and shift their arrival earlier than birds in the Northeast given the same amount of warming. We’re still working out why this might be the case, but one hypothesis is related to seasonality and the rate of change in temperature over the course of spring. In the Southeast, that rate of change is typically slower, and so a fixed amount of warming corresponds to a longer passage of time compared to up north. At any rate, we wouldn’t have known there was an interesting pattern to investigate without all of your observations. Thanks to all of you who contribute to eBird!

This paper is published in the open access journal, PLoS One, which means that anyone can access and read the paper for free here.

Citation: Hurlbert AH, Liang Z (2012) Spatiotemporal Variation in Avian Migration Phenology: Citizen Science Reveals Effects of Climate Change. PLoS ONE 7(2): e31662. doi:10.1371/journal.pone.0031662

Contributed by: Dr. Allen H Hurlbert, Department of Biology, University of North Carolina, Chapel Hill, North Carolina

Allen Hurlbert was recently interviewed by the CBC radio along with our February eBirder of the Month, Mike Burrell and Bird Studies Canada’s eBird coordinator, Dick Cannings. We think you will enjoy the interview, which you can listen to in its entirety here.

Background: All data entered into eBird are free and accessible to researchers and conservationists at the Avian Knowledge Network. A list of publications that use eBird is available here.