San Diego Natural History Museum--Your Nature Connection[San Diego County Bird Atlas Project]

WRENDERINGS
Reports from the Field
Fall 1997

Reflections from Square L12, Blue Sky Ranch
First Sooty Tern Nest for the Western Continental United States Found in San Diego County
Perspective from the State Parks


Reflections from Square L12
Blue Sky Ranch

Habitats in northeast Poway's L12 include chaparral, agricultural (mainly avocado), residential, coastal sage scrub, two reservoirs, and narrow riparian woodlands. At the heart of the square is Blue Sky Ecological Reserve, a riparian woodland surrounded by chaparral and coastal sage scrub. As it is only ten minutes from our home, my husband Bert and I have visited it by car and on foot for almost thirty years, delighted when the reserve became protected. Green Valley Truck Trail is now closed to vehicles, eliminating the once pleasant drive from Espola Road to Highland Valley Road. All public traffic is now on foot.

Through the years we have seen enormous changes as wildlife habitat in the rest of the square has been lost to development. Most of the grasslands are gone along with a great deal of the coastal sage scrub. Where mansions now overlook Green Valley Truck Trail, White-tailed Kites once hovered, nesting in the creek's sycamores. Meadowlarks were abundant, and Western Kingbirds nested in adjacent eucalyptus trees. A remnant creek flowed west from the Poway water-treatment plant, providing cover, water, and food for many animals.

During the past breeding season, we have looked at these areas more critically and discovered bird activity not noticed or not occurring in prior years. Probably our most exciting observation was of three fledgling Say's Phoebes being fed in disturbed vegetation at the base of a high man-made soil bank below one of the mansions. Two other observations were almost as exciting. One was being close enough to Western Flycatchers to hear their faint but charming songs. The other was watching and hearing a Rufous-crowned Sparrow skylark several times.

Yellow-breasted Chats are heard and/or seen almost every spring; however, they are erratic in remaining to breed. At Blue Sky and riparian areas downstream, we heard and saw four on 6 and 16 June. Next year we should have permission to get into those areas and collect better data, along with good cases of poison oak.

As in the rest of coastal southern California, Crows have moved into L12 in great numbers. Lake Poway Park is especially favored by these birds. Cassin's Kingbirds and Bullock's Orioles vigorously and vociferously defended their nests against the Crows.

House Wrens continue to build nests in challenging locations. One was clinging to an inside wall of an owl's nesting box tipped within 45 degrees of bottom side up. Another was built within a horizontal 4-inch pipe, part of a gate by which hikers squeeze. Birds fledged from both nests.

There are two pairs of Red-shouldered Hawks known to me in areas we surveyed. As far as I could tell, the Blue Sky pair did not reproduce this year. A pair west of Old Coach Road fledged one young. The Blue Sky Cooper's Hawks fledged two of their three chicks. The third had been very much a runt. For several years these hawks have used the same outwardly dilapidated nest in an oak tree over a major trail junction. The incubating bird leans out, peering down at the many people who come to see the ongoing show. Only once have we experienced aggression. The male swooped from his perch in a nearby sycamore as we raised our binoculars, passing very close to our heads. It was impressive through binoculars! Red-tailed Hawks nest in a sycamore at eye-level height from our hillside view. They fledged three young this season.

California Gnatcatchers seem to be thriving in the suitable habitat remaining. We located most of those plotted on the habitat map where we were able to walk, plus two more pairs.

White-tailed Kites nested to the north or west of our square. Some grassland remains in those directions but is soon to become more estate development and a very large golf course. We did feel a thrill when they appeared at the west end of Blue Sky a few times recently. We have seen the juvenile there alone, and hope they will find territories that can sustain them.

Two energetic friends have provided wonderful coverage of Blue Sky's night birds and others. They confirmed breeding of Western Screech Owls and sightings of Great Horned and Barn Owls along with multiple calls of the Great Horned. The tree in which the Great Horneds formerly nested blew down last winter. Our friends were not able to find the new nest. Thank you, Richard Roedell and Patty Heyden.

Some areas of L12 we did not survey this season. Our target list was 64 species, many of which we did not find. But we did add nine species. Out of 59 possible breeding species, we confirmed 30. It's been great good fun!

--Margaret McIntosh


First Sooty Tern Nest
for the Western Continental United States Found in San Diego County, Atlas Block U10 (South Bay)

The South Bay block, U10, supports a wide variety of nesting seabirds and shorebirds. During recent years, Black Skimmers and up to six species of terns have been known to nest there at the Western Salt Works.

This year, while conducting surveys to monitor nesting success, John Konecny, Eric Hein, and I discovered a Sooty Tern nest. This is the first Sooty Tern nest ever to be recorded in the western U.S. outside of Hawaii, thus furnishing the atlas with not only a new breeding species for the county, but for California as well. The nearest likely colonies are at Las Rocas Alijos (in the Pacific west of Baja California Sur) and the Hawaiian Islands.

Sooty Terns were first noted at this site and others in 1996. The first observation in 1997 at this site was on 15 April, when a single bird was noted flying around. Observers on 16 April also recorded a single bird. No sightings were reported again until 30 May, when a pair was noted roosting at the intersection of two dikes.

On 3 June, we found a single bird incubating an egg. The nest, just a scrape in the ground, was located within a mixed flock of Forster's Terns, Least Terns, and Black Skimmers. As we entered the colony, the Sooty Tern did not attempt to drive us away from its nest in typical tern fashion, but rather just stood off to the side while we examined its nest. As soon as we were about 15 meters distant, it sat back down to incubate again. This behavior would apparently be its undoing.

We next visited the site on 6 June; again a single bird was incubating the egg, but the carcass of the other adult was found only 10 meters from the nest. The remains consisted of only wings and a severed head. We suspect an immature Peregrine Falcon in the predation. On the next visit, 10 June, the other adult was found dead in almost the same spot. The bird had a massive head and neck wound and was disemboweled. The egg and carcasses were placed with Phil Unitt in the San Diego Natural History Museum, providing California's first Sooty Tern specimens.

--Michael R. Smith


Perspective from the State Parks

Covering four atlas squares in three state parks, reaching from the badlands of Borrego to lush Palomar Mountain, has been exceptionally rewarding and dropped some surprises in my lap. I've been forced into changing my all too frequent birding pattern from the Christmas Bird Count mentality of "species listing" to "bird watching." Now, I'm continually telling myself it's okay to slow down and sit in one place and actually watch birds' behavior. Years of "maximum coverage" have diminished my patience for observation. The atlas project is renewing the pattern of birdwatching I enjoy by far the most. Sample surprises:

While sitting on the edge of a meadow in Cuyamaca I saw a White-breasted Nuthatch drop down to the ground with food and disappear into an old fallen oak limb. Approaching, I found a nest cavity with young less than 12 inches off the ground. I always thought you had to look up to find nuthatch nests!

The first day in my Borrego Badlands square, E28, I walked for half an hour without seeing or hearing a single bird--not even a raven. Later, I found two large stick nests, one with a female Red-tailed Hawk on it.

During two visits to Green Valley Campground to survey a proposed park development, I observed seven species nesting in one large live oak. For the record: Plain Titmouse, Western Bluebird, House Wren, Ash-throated Flycatcher, Western Wood-Pewee, White-breasted Nuthatch, and Lawrence's Goldfinch. Hutton's Vireo nested in the understory nearby. Too bad it wasn't in my square!

In probably the wettest spot in San Diego County, I sat by a Palomar stream one June day watching trout and listening to songs of the resident birds. Then I heard a sound that didn't fit. A male Nashville Warbler was singing for all he was worth. Nashvilles are not known to summer here, and after watching this one for nearly an hour I suspect he was singing in vain. On 28 July, at the same spot, I saw a pair of Wilson's Warblers, which formerly nested with some regularity in the county but are now very rare as a breeder. I'm going to cover this unique "island" mountaintop thoroughly in the coming years.

I startled a mature Golden Eagle off an earthen dam on Palomar. As I watched it gliding away through my binos it turned about a half mile out and flew directly back toward me. It kept getting bigger and bigger through the lens until I thought it was going to hit me. When it got too close to focus on I dropped the binos to see every detail of this bird with its magnificent 7-foot wingspread from several feet away.

--Paul Jorgensen, Resource Ecologist
California State Parks, Colorado Desert District

birdatlas@sdnhm.org

Fall 1997 Wrenderings | Wrenderings Archive | Bird Atlas Introduction