Wednesday, January 15, 2014

BROWN PELICANS IN WASHINGTON


When I moved to Washington in 1967, Brown Pelicans were rare in the state. Formerly common and widespread on all coasts of the US, their populations had crashed over a period of decades. Only after some time and much research did the cause become clear. Beginning soon after the Second World War, DDT was developed as the first of the modern synthetic pesticides. Within a short time, it had been liberally applied to crops all over the continent and to settled areas to combat the mosquitoes that transmitted diseases such as malaria.

DDT accumulates in tissues and becomes concentrated as it passes up the food chain. Fish picked it up from the water and passed it on to the pelicans that ate them, concentrating the chemical in pelicans more and more. One of its byproducts, DDE, interferes with calcium metabolism and as a consequence, the birds weren’t able to produce sufficient calcium for their eggshells. The thin-shelled eggs cracked when the adults attempted to incubate them, and reproductive success dropped precipitously all around our coasts.

The consequences of using this pesticide became so obvious that in 1972 the Environmental Protection Agency banned its use in the US. Fish took up less of it, eventually pelicans were pretty much free of it, and their nesting success improved greatly.

By the end of the 20th Century, Brown Pelicans had become common again on the Pacific coast and were coming up to Northwest waters in numbers never seen before. Now thousands of them visit our outer coast every summer to take advantage of fish populations apparently greater than those around their breeding grounds in southern California and Mexico. A small number of birds make their way all the way down to southern Puget Sound, and a few even stay through the winter now.

Our pelicans are a good mixture of adult birds with white heads and dark underparts and juveniles with brown heads and white underparts. They roost in large flocks on sand islands, jetties and piers and launch into the air to feed after long sessions of resting and preening.

This unmistakable bird is an aerial plunge diver. Single pelicans, sometimes in groups, fly several meters above the water and, when they spot a fish or school of fish below, they fold their wings and drop like a plummet, piercing the water with their long bill and almost completely submerging. When the bill reaches one or more fish, it opens and water rushes into the huge pouch. The pelican lifts its head and lets the water drain out, keeping the fish inside to be swallowed.


Heermann’s Gulls, breeding in the Gulf of California, also move north along the Pacific coast, becoming common in Washington waters while the pelicans are here and then moving south again in late fall.

When a pelican dives, it may be accompanied by one or more of these kleptoparasitic gulls. If a fish falls out of a pelican pouch, a gull is often there to grab it.

Dennis Paulson

1 comment:

Mary Jacobs said...

Quite a few pelicans usually summer on the southern Oregon coast. This year they were absent. Lately they have been migrating south. I was wondering if the uptick of numbers in the puget sound area was due to lack of feed on coastal Oregon.