Wednesday, January 6, 2016

Unseasonable Weather and Local Birds

At long last it seems winter has finally arrived in the southern piedmont, but only after an unprecedented stretch of warm temperatures. I have seen temperatures in the seventies at Christmas before, but the period of time those temperatures held on this time was a first for me.

Locally, ornamental plants bloomed way early. Upland chorus frogs, southern leopard frogs, and spring peepers were vocalizing. Turtles were basking up the warmth and wandering from pond to pond like it was spring. At the coast blue crabs were still active in the waterways.

I fielded some questions about effects the unseasonable stretch had on area bird populations and diversity, and now that the Christmas Count season is over I think the answers are obvious. Most all of the rare and uncommon species found on piedmont and coastal counts were of lingering land bird species. Ducks and gulls, just two groups of birds that normally don’t arrive in big numbers until there is a freeze-up to the north, are at lower than normal numbers. And, in general it seems that overall numbers of all birds are just down this year. I think more are just lingering to our north.  Cold air arrived this week so maybe we will see an uptick in the numbers of birds in all habitats.

Lingering species that were recorded on Christmas Counts I participated in include Lincoln’s sparrow, gray catbird, common yellowthroat, Cape May warbler, Nashville warbler, cave swallow, black and white warbler, orange-crowned warbler, blue-gray gnatcatcher, sora, and green heron. All of these may be present in any given year but in tiny, undetectable numbers. The fact that so many of them were found this season indicates that there are lots of them out there. That’s an impressive list.

So do the late spring-like temperatures have an adverse effect on the birds that are here? I doubt it. Our winter birds experience the most survival challenges when there is prolonged extreme cold with frozen precipitation. This has been a stress-free start to the winter for local winter species. That makes them less susceptible to predators, which is why I think some hawk numbers are down locally. I have had to work really hard to find Cooper’s or sharp-shinned hawks; two species that prey upon small land birds. 

Green Heron by Jeff Lewis
Species that tend to linger in our area until cold forces them out, like the green heron above, are in higher numbers so far this season. Our winter resident species, like the fox sparrow below, are in much reduced numbers so far. I suspect they are they are lingering farther north until they will be forced down by weather.  

Fox Sparrow by Lee Weber