LAKE FOREST – Local scientists say increased sightings of birds such as the red-tailed hawk and American kestrel in local wilderness parks are an indication that raptors are rebounding from the devastation that burned almost 90 percent of Whiting Ranch and Limestone Canyon following the 2007 Santiago fires.

A new survey done of raptor nesting habits by the Irvine Ranch Conservancy and Bloom Biological Inc. has shown an increase of the raptors in the area. In the case of the Santiago wildfire, it has taken at least four years for raptor numbers to rebound.

“We were thrilled to see 2011 raptor nest numbers near pre-fire values, though 2011 was an exceptionally productive year both in burned and unburned areas,” said Jutta Burger, co-director of science and stewardship. “This year, our preliminary estimates from raptor biologist Scott Thomas are that we are about 5-10 percent down from 2011 numbers, which means we should continue to monitor them and take actions we know will improve their chances of nesting successfully.”

The broader the food base and habitat requirements, the more easily a species can rebound from disturbance such as fire, Berger said. Scientists are least worried about the Coopers hawk populations because it appears the species have adjusted its habitat requirements to include more urban landscape. Still, Burger said, fewer Coopers hawk territories were found this year than in 2011.

This year’s study confirmed that a resident bald eagle pair again successfully reared two young but a golden eagle pair failed. Burger said identifying the causes of nest success or failure using more detailed surveys or long-term data will help manage populations of these birds better.

Burger said the return of the white-tailed kite have local scientists most excited. Only a few years ago this bird could not be found nesting on the Irvine Ranch Open Space.

“They are prey specialists that feed on voles, so seeing them back here means that we have good habitat for them with plenty of food,” she said.

On Friday a birding tour led by a volunteer from the Irvine Ranch Conservancy will be the first of many planned to view the rebounding raptors. On Saturday a Wilderness Access Day at Limestone Canyon,which is owned by OC Parks, will allow people to hike on their own in that same area.

Hikers can see white-tailed kites, red-tailed hawks and red-shouldered hawks from open trails in Limestone Canyon. Northern harriers might also be seen from the trail in the grasslands on Loma Ridge, and American kestrels may also be seen darting between the oaks or perched and holding lookout for prey. An occasional glimpse of a Swainson’s, a sharp-shinned or a zone-tailed hawk is also possible during spring migrations.

In 2011, Bloom Biological reported 25 red-tailed hawk nests and 11 white-tailed kite nests. The survey also documented one bald eagle, one golden eagle, one northern harrier, five Cooper’s hawks, and six red-shouldered hawks in and around the OC Parks’owned Irvine Ranch Open Space.

The Irvine Ranch Conservancy offers more than 100 monthly docent-led programs on land it manages for OC Parks. Wilderness Access Days are held twice a month – one in Bommer Canyon and one in Limestone Canyon. In October, a Wilderness Access Day will be added in Black Star Canyon.

Access is limited to the public to preserve the land which has been designated National and California Natural Landmarks for their rare biological and geological features. The landowners have entered into legal agreements with state and federal wildlife and conservation agencies to balance human access and wildlife protection.

The limitation of public access lets the wildlife forage, find water and rest each day in order to stay healthy. The more humans unintentionally interfere with these processes the harder it is for the wildlife to perform basic survival activities – for wildlife this can result in energy loss, missed feeding opportunities or longer spans without water.

Contact the writer: 949-454-7307 or eritchie@ocregister.com or twitter.com/lagunaini