April 26th – Survival and the “Disconnect”

I have been struck over the past week or so by the fact that the leaves have emerged on the trees and shrubs at Ruthven but the birds that normally would be taking advantage of the insects and catepillars that this engenders are not here yet to take advantage of them – there is a “disconnect”. These typically are long-distance or Neotropical migrants. Bridget Stutchbury, in her newest book Bird Detective, asks: “Behaviour, and the ability to adapt to new circumstances, is what could make or break a species’ future survival. As spring arrives earliere each year, can birds simply learn to begin breeding earlier?” Right here, plants, insects, and short-distance migrants or resident birds can respond to the local conditions. But long-distance migrants don’t have a clue what is going on 1,000-2,000 miles away. They’re getting their cues from the length of day – something that has nothing to do with global warming. This is the disconnect. There’s a chance that the food resources that the birds were counting on will be done and gone by the time they get here.

It started off as a miserable day: cool and windy and rainy. we opened only the more sheltered nets and a bunch of traps – which was a good thing as over half the birds caught were in traps. We tallied (but didn’t band) 4 new species for the year: Black-crowned Night Heron, Broad-winged Hawk (a bird we rarely see here), Wood Thrush, and Bobolink. As interesting as these were, the banding was pretty slow.

Banded 18:
2 Mourning Doves
1 Hairy Woodpecker
2 Chipping Sparrows
2 Field Sparrows
1 Song Sparrow
2 White-throated Sparrows
3 Dark-eyed Juncos
1 Red-winged Blackbird
1 Brown-headed Cowbird
3 American Goldfinches

Retrapped 25:
1 Black-capped Chickadee
1 White-breasted Nuthatch
9 Chipping Sparrows
1 Field Sparrow
1 Song Sparrow
5 Dark-eyed Juncos
3 Brown-headed Cowbirds
4 American Goldfinches

ET’s: 45 spp.


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