Gavan P.L. Watson
photo credit: Jim Frazier
Research published in Vol. 126, Iss. 3, pg. 579 of The Auk has some interesting implications for habitat conservation for migrating bird species here in eastern North America. In short, during Spring and Fall migration, migrants showed no preference for stopover locations based on distance from a continuous, connected (river corridor) habitat, nor were they more likely to be concentrated in one forest patch over another. Plainly, the migrating birds appear to show no preference for connected habitats versus fragmented ones. Clearly, if this is the case, birds are using other criteria to select where they stop while migrating.
What is interesting, and not surprising, is the finding that during Fall migration, birds do select habitat described as “early succession forest” with high density of native and non-native fruit-bearing trees and shrubs. In the cannon of conservation, habitats that are fragmented or in the early stages of succession are seen as lower quality when compared to continuous and stable habitats. And this may still be the case when it comes to nesting (less nest predation in larger forests, for example)—but it would seem as though we might need to re-evaluate the assumption that these younger, more fragmented landscapes are of little or no use to birds and ultimately, bird conservation.
As migratory stopovers, it would seem that all forested landscapes—no matter how mature—are important.
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3 Responses to Fragmented & Young Forest preferred by Migrating Songbirds
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I found this information interesting and I guess a little surprising compared to some other reports I’ve heard that expressed concern about forest fragmentation as it impacts migrating birds. It IS encouraging though.
Could the choice of habitat in fall migration be impacted by the 1st year birds in the flock?
@Zen Birdfeeder
That’s an interesting question that I don’t have a good answer for. If I was to enter into conjecture, I suspect that since all birds need to fuel up and re-fuel, so to speak, while migrating, that they may be choosing these places regardless of if there are first-year birds with them. I’m reminded by Dr. Bridget Stutchbury’s recently-published work that showed that spring migration was much faster than fall migration (in two bird species, at least). Fall migration may be more “leisurely” due to the search for food.
Good to be introduced to this paper as I’m currently writing/thinking about migration. Similar findings to the one by Bonter, Gauthreeaux, and Donovan, who used radar technology to find pockets of migrants. A snippet of their abstract “Concentration areas were characterized by 1.2 times more forest cover and 9.3 times more water cover than areas with little migrant activity. We detected a strong negative relationship between activity of migratory birds and agricultural land uses. Examination of individual migration events confirmed the importance of fragments of forested habitat in highly altered landscapes and highlighted large concentrations of birds departing from near-shore terrestrial areas in the Great Lakes basin.”
And now, I’m off to see migrants landing in the near-shore banding station at Braddock Bay Bird Observatory!