Owls Starve as Drought Drags On

Owls Starve as Drought Drags On

Raptors and owls in Southern California, particularly at Audubon's Starr Ranch, have had an unusually bad breeding season.

by Elizabeth Newbern
Published: 08/26/2014

Editor's Note: This is the third of three short profiles explaining how the California drought is negatively impacting birds in the area.

The California drought still hasn't let up--in fact, it's projected to cost $2.2 billion according to a study from UC Davis Center for Watershed Sciences. Beyond the economic ramifications, local wildlife are struggling--both waterfowl and passerine bird populations have dropped. But even less water-dependent species have taken a hit: Raptors and owls have had a rough breeding season in southern California and many experts think that the drought played a major role.

At Audubon's Starr Ranch, there are eleven predatory bird species that normally nest on the property. "A lot of these raptors--if they lay eggs--they do it within two to three days of the same time each year," Starr Ranch manager Peter DeSimone says. But this year not only was he not seeing new signs of nesting, but several raptor species--notably the Red-tailed Hawk, which usually nests all over the property--were nowhere to be seen

He suspects that the disappearance of breeding raptors is linked to the food chain. The food supply is shrinking all along the chain and raptors are the latest victims. Most birds of prey eat a variety of small mammals and insects to sustain themselves, but the drought has put a dent in their food source. Prey populations--like mice--are shrinking because the local grasses and plants they depend on for food aren't able to grow in the hot, dry drought conditions. Put it all together and you have a recipe for starving predator birds and hungry birds leads to less breeding success--up to 90-95 percent reduction for this season according to experts.

One of the species most notably affected was the Barn Owl. Starr Ranch is well known for its Barn Owl cam project, where they monitor a nesting pair during the breeding season, but this year viewers were left without much to see. Although a pair of Barn Owls did make a nesting attempt, shortly after the first egg was laid, the male owl stopped returning to the nest and the female left shortly thereafter--neither returned.

"We don't know what caused that pair to cease its nesting attempt," says Peter Bloom, zoologist and environmental consultant. He explains that in times with limited water supply and resultant limited food sources owls and hawks are going to experience lower reproductive success, but it's unclear what happened in this situation. The female may have left because the male didn't bring enough food or she may have been affected by a threat unrelated to the drought, such as rat poison, Bloom explains. "We don't want to jump, on very little clues, to big conclusions," Bloom says.

In fact, Bloom thinks the current decline in raptor populations may have causes beyond the current drought. The dramatic drop in raptor populations isn't a statewide phenomenon--instead, it seems to be centered in southern California where there is a large urban population. "I think [the population drop] is more severe than what I would have thought a drought would produce," says Bloom. He suspects that urban threats, such as disease and rodenticides, may be playing a large role as well, but as of yet there is no scientific evidence that points to any of these as the definitive cause of breeding population decline.

To get to the bottom of this mystery in southern California, Bloom thinks a large scale observational project of raptor populations is called for. "The need for this sort of work has never been previously identified," he says. "It might be time now."

Author Profile

Elizabeth Newbern

Elizabeth Newbern is a reporter for Audubon magazine. Follow her on Twitter @liznewbern.

Type: Author | From: Audubon Magazine

Comments

Drought, global warming,

Drought, global warming, pesticides, human population, loss of habitat, etc. Our precious wildlife does not stand a chance unless we step up for them. My area used to have allot of vacant land, now we have allot of vacant buildings. If someone sees an area of undeveloped land they grab it for human purposes, office buildings., condos, single family homes, golf course, stores, etc. Each time they do this they are destroying the wildlife that uses the land for shelter and homes. Then we get upset when the animals move into human territory. If we do not care about the animals then we will lose them. We need to wisen up and look for ways to assist all wild life. This goes for forest areas as well. The animals need forests for survival. Humans need forests and animals for our survival as well. If we had not cut down so much of our forests, then maybe global warming would not have happened so quickly.

It's amazing how little you

It's amazing how little you hear about the impact of droughts on wildlife from mainstream media. All they ever talk about is how much is it going to cost and how it negatively affects humans.

The truth is, Flowers

The truth is, Flowers believes the latest diminish throughout raptor populations often have causes past the latest drought. The actual extraordinary drop throughout raptor populations is not a statewide phenomenon--instead, it seems to be focused throughout lower Colorado where by there's a big urban inhabitants. "I feel [the inhabitants drop] can be worse when compared with exactly what I would include believed some sort of drought would likely create, inches states that Flowers. He suspects in which urban provocations, such as condition along with rodenticides, could be enjoying a huge part at the same time, although at the time of but there isn't a medical facts in which items in order to all of these because the conclusive cause of reproduction inhabitants diminish.

I live on an acre by Santiago

I live on an acre by Santiago Park & have transformed my property to native/drought tolerant plants. It is a Certified wildlife habitat. Point is, I have documented for 5 years the birds that have come to our property, when plants bloom, when each butterfly species arrives,etc. things are changing! Our Screech Owls & Blue Birds returned and were successful in raising their families. One new thing I've noticed is the increase of the rat, mouse & squirrel populations. People are using poison. That needs to stop there are several electric & live traps (if you must) on the market . They work great. I could go on , but I won't

Have you read this!

Have you read this!

Please call all of the TV &

Please call all of the TV & Radio Stations and get them to do an story on feeding and watering wildlife. They need help now.....

Please contact both the TV &

Please contact both the TV & radio stations nd get them to do an story on the wildlife. Please feed and water during this dry season.

Great Post... Thank You for

Great Post...
Thank You for sharing,
i love owl too

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