CA Drought Killing Birds of Prey

The drought in California is not just hitting farmers hard; it’s threatening populations of birds of prey. Those populations are suffering through what may possible be their worst breeding year on record; a 90-95% rate of failure.

Researcher Scott Thomas said:

At the end of 2013 we started seeing more failure than we would have expected. This year, most of the nests are inactive. No doubt they were starving early, because they didn’t start anything. This year, the birds we’ve trapped are extraordinarily skinny. You can see they’re thin, and their hunting behavior is different.

Veterinarian Kristi Krause from the Serrano Animal and Bird Hospital commented, “They’re skinny, they’re weak and they’re just not doing well.This is probably the worst I’ve seen it.”

Thomas said the drought has harshly reduced the number of  plants and seeds that increase  seasonal bursts in populations of rodents and other small mammals, which means that birds of prey have less to feed on.

Pete Bloom, Thomas’ research partner, who has tracked  birds of prey in Orange County since the late 1960’s, said, “It’s alarming. This is probably the worst I’ve seen a local raptor population decline to. It is probably coastal Southern California-wide – at least that.”

Bloom also attributed the breeding failure of the raptors not only to the drought, but also to anticoagulant rodenticide, which eventually poisoned raptors, and West Nile virus.

The decline in birds of prey has been reported from San Diego to Ventura counties, especially in the Orange County wildlands. The decline has a financial impact as well; the Audubon Starr Ranch Sanctuary in Trabuco Canyon is largely funded donations, and the popular webcams that elicit donations are not as interesting because the populations viewed are simply inactive. Manager Pete Simone said, “This year, either the bird nests are vacant … or they start out laying eggs, and they’re bailing.”

Thomas stated that among the 25 red-tailed hawk nests he watches north of the 405, only one seems active; south of the 405, only three out of 12 are active. He added, “That foraging behavior strongly suggests they’re starving. Raptors don’t have a great deal of (breeding) success. When you get a year when you’re missing an entire generation, they’re not structured to sustain that for very long.”

Bloom was quite worried about one species, saying, “The white-tailed kite is almost already gone from Orange County now. If the drought is a major contributing factor to the kite decline, hopefully the drought will end one day and they could return. But on the short term, this is certainly a huge decline in both kites and other common raptors.”