Dramatic changes in Ruby-throated Hummingbird migration: They’re arriving earlier, migrating slower

8/13/2013 | 8

Ruby-throated Hummingbird in Whitehouse, Texas, by docdpp.

Ruby-throated Hummingbird in Whitehouse, Texas, by docdpp.

Ruby-throated Hummingbirds are well-studied indicators of how climate influences migration.

That the birds are arriving on their breeding grounds earlier today than in previous periods has been demonstrated repeatedly. Now investigators have learned that differences in the hummingbirds’ first-arrival dates vary by latitude.

The researchers analyzed weather conditions in the eastern United States and Central America between 1895 and 2010, and plotted the latitude of more than 36,000 sightings submitted to the North American Bird Phenology Program from 1880 to 1969 and to hummingbirds.net and Journey North from 2001 to 2010.

In addition to showing that winters and springs are warming, a conclusion consistent with a growing body of scientific evidence, and that hummingbird arrival dates were advanced at all latitudes, the analysis revealed that Ruby-throats are arriving 15 days earlier at lower and middle latitudes (between 33°N and 41°N) but only 11.5 days earlier at higher latitudes (42-44°N).

Even more surprising, the Ruby-throats’ rate of migration appears to be slowing. In recent times, the birds have been taking an average of 38.0 days to travel from 33°N to 45°N, more than four days longer than the average trip required during the historical period, 33.8 days. An increase in the availability of hummingbird feeders along migration routes may partially explain the delay, write the researchers.

They published their study in the January 2013 issue of The Auk, the quarterly journal of the American Ornithologists’ Union.

Read the paper:

Jason R. Courter, Ron J. Johnson, William C. Bridges, and Kenneth G. Hubbard (January 2013), Assessing migration of Ruby-throated Hummingbirds (Archilochus colubris) at broad spatial and temporal scales (Evaluación de la Migración de Archilochus colubris a Escalas Amplias de Tiempo y Espacio). The Auk, 130 (1): 107-117 (pdf).

A version of this article appeared in the August 2013 issue of BirdWatching magazine.

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  • Karyn Borkowski

    Is it a bad thing to feed them during migration or is good because they can get extra energy and take their time?

  • andy

    The delay makes no sense to me. If anything I would think it would speed up as birds are able to move north faster in advance of normal flower and insect availability because people have feeders out.

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  • Gerry Miller

    What happend to the post I just made??? You clowns took it out cause you didn’t like it???

  • Gerry Miller

    What climate changes???? The climate has not changed in the last 16 years!!!! Don’t tell me you believe in man made climate change??? Because that is as big a hoax as Obama.

  • Nick Colombo

    What i’ve read about hummingbirds is,they leave when the days get shorter.The shorter daylight triggers a hormone,has nothing to do with temps.Theres also not very much information on hummingbird migration,we’re still not sure how they get across the gulf of Mexico.Last year (2012) they arrived in my area(NY) in mid April,this year they arrived mid May.If anything it’s getting cooler and they’re migrating later.I also noticed they left already.Last year they were here until mid Oct.We had one stay until the 2nd week of Nov.

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  • Russell P

    Gerry…note the dates of the study (1880-2010). Temperature change in the past 16 years is irrelevant. THIS graph is relevant:
    Regardless of whether the warming trend is caused by human activity or not, there HAS been a warming trend and there are dozens of studies documenting plants and animals changing their patterns in response to the warming trend.

    Nick…I doubt that we know enough about what triggers hummingbird migrations to say it has nothing to do with temperature. It’s not like we can put them in the lab to see what triggers migration! They fly across the Gulf….flapping their little wings!