Friday, March 31, 2017

Two world conquerors

I photographed two bird species in Borrego Springs recently that I originally included in the trip report. The things I wrote about them, however, didn't go with the theme of the trip report. So I cut it out and present it separately here.

Some idiot uninformed person decided that every bird that William Shakespeare ever mentioned in his poems and plays should be naturalized to North America. Thus, for a time in the late 1800's one might hear Skylarks and Nightingales and other English birds in various cities in North America.

Soapbox time: When you take a plant or animal from its natural habitat and let it loose in an alien environment, one of two things can happen. It will either die a horrible death, or it will grow in population exponentially and completely overrun its new home and outcompete similar native life. History is replete with examples. From rabbits, goats, and rats destroying Pacific island paradises, to the dandelions in your yard. Himalayan blackberries in the Pacific Northwest. Brazilian pepper trees in southern California. The same goes for letting your no-longer-wanted pet turtle go at the local pond and killing the native turtles, or (sorry to offend) letting your housecat out of doors where they kill 1.4 to 3.7 billion birds each year.

Thus it is that most birders loathe the European Starling. This bird was brought to the United States in the 1890's and a release in New York City led to every one of the starlings in North America today--60,000,000 birds. They're messy, they're noisy, they group into winter flocks of 100,000 or more, they're aggressive toward native songbirds. They have been implicated in the population crash of bluebirds and other birds that nest in old woodpecker holes--usurping them for themselves. But, admittedly, when they attain their breeding finery, and aren't flocking in their usual dirty brown plumage, they can be attractive.

European Starling
Some birders call them "Sky Rats"
European Starling
European Starling putting his best foot (plumage) forward. Borrego Springs, California. March 12, 2017. Greg Gillson.
While the European Starling conquered North America in about 70 years (1890-1960), the Eurasian Collared-Dove did so in only 26 years (1983-2009). This large pigeon accomplished this with strikes that would make Alexander The Great proud. Starting in Florida--of birds perhaps escaped from captivity in the Bahamas--individuals bred, then flew hundreds of miles (primarily to the northwest), and did so again. Their offspring did likewise until they reached Alaska in 2009. Some birds remained behind and are still filling in the "holes" left behind. Unlike the Starling, these doves seem to get along with native doves and other birds. But their sheer volume means they are consuming huge amounts of food formerly eaten by other birds, especially the native Mourning Doves. What the eventual outcome will be, we'll have to wait and see.

Eurasian Collared-Dove
Some birders call them "Sky Rat Lattes"
Eurasian Collared-Dove
They look so innocent.  But when their population grows exponentially, bad things happen.
Eurasian Collared-Doves. Borrego Springs, California. March 12, 2017. Greg Gillson