Sunday, March 27, 2011

Feeding Opportunities

When you get a sudden arrival of random photographs from folks, it's always nice to use them - but finding a way to tie them in to a blog post subject is not always easy. Having just received some great photos of Northern Gannets feeding in the Delaware Bay from Cindy Ferguson, I wondered how I could tie them in with the Pine Warbler pictures that I was sent by Pat Sutton. Pat and I had been talking about Pine Warblers on Friday, as there has been a nice male visiting the Northwood Center feeders for several days now, and Pat told me that she and Clay had seen a Pine Warbler visiting their feeders too, since March 14th.

Then the link struck me; feeding opportunities! Many species of birds are successful because of their opportunism and their willingness and ability to adapt. Pine Warblers are - like all American Wood-warblers - essentially insectivores, but they are one of the earliest migratory members of their family to arrive back on their breeding grounds and no doubt regularly find a shortage of insects during the often chilly days of March. Being able to adapt thus enables them to continue to arrive early; there's a fair chance that your first Pine Warbler of the year that you actually see (rather than hear singing in the top of a pine) will be feeding on the ground. Almost certainly, it will be picking up pine seeds that have dropped from the cones over the winter. Similarly, the Pine Warblers at our feeders are mucking in with all the other birds and getting by on a variety of seeds - I haven't seen if our Northwood bird is showing a particular preference, but Pat & Clay's bird apparently favors sunflower hearts.

Male Pine Warbler eating sunflower hearts at a feeder in Goshen [photo by Pat Sutton].

Male Pine Warbler eating sunflower hearts at a feeder in Goshen [photo by Pat Sutton]. As males of many migratory species head north to establish territories before the females arrive, it will likely be males more often than females that indulge in feeder feeding.

So what about the Northern Gannets? Well, they're opportunists too, but perhaps in a more obvious way. Northern Gannets have to be visual hunters to find their food - fish that live underwater (actually, there's another phrase for Tony - underwater. Fish don't live under the water, they live in it!!). So they will check out any visual clues that might come thier way. This must surely include more than just spotting the fish themselves, as gannets will surely soon learn to keep an eye out for other gannets feeding, or even other bird species, mammals such as whales, and even large predatory fish such as tuna and sailfish. So it doesn't take a Northern Gannet long to work out that all those gulls are following that boat for a reason! Fishing boats are, of course, worth checking, as the crew may be cleaning the catch and throwing the waste overboard. But any boat will churn up water to a greater or lesser degree and this can bring up potential food items from deeper water, or simply attract fish, which in turn attract birds.

Northern Gannets fishing off the Cape May-Lewes Ferry on our Poor Man's Pelagic trip on Saturday, ably led by Janet Crawford and Karen & Brian Johnson. If you missed this trip - which looks like it was a real fun one to be on - check out our Field Trip Reports for full details (and details of all of our recent walks in the area). [Northern Gannet photos by Cindy Ferguson]

As a short Post Script, you might be interested to know that the first record of a Yellow-rumped Warbler in the British Isles was of a bird visiting a garden feeder in Devon, SW England from January 4th to February 10th 1955. Sadly it was picked up dead on the last date, but it was clearly doing its best to adapt to a decidedly unfamiliar experience!

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