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

WRENDERINGS
Notable Observations
Fall 2001

drawing of Yellow-billed Cuckoo

Yellow-billed Cuckoo
 
drawing of Swainson's Thrush

Swainson's Thrush



drawing of Mountain Chickadee

Mountain Chickadee

Even after five years of combing the county for breeding birds our observers continue to turn up unexpected discoveries. Thanks as always to Mike Evans for maintaining the website with the spreadsheet of reports to the San Diego Field Ornithologists' rare bird hotline (619-NUT-BIRD).

Presumably the same bird that hangs out with the Black-crowneds at Scripps Institution of Oceanography, an adult Yellow-crowned Night Heron showed up at Famosa Slough (R8), where Ginger Johnson reported it on 17 May. Ken Weaver and Pete Ginsburg confirmed that White-faced Ibises continue to nest successfully at their two known colonies, Guajome Lake (G7) and San Luis Rey River valley just east of Interstate 15 (E9), but their nesting attempt at Calaveras Lake (H7) was evidently aborted.

Art & Dorothy Hester encountered a Zone-tailed Hawk, far less frequent in the breeding season than in winter, just east of Campo (U23) on 27 May. Randy West informed us that the Harris' Hawks near Boulevard (S26) still had young in their nest (the same as last year's) on 23 July.

Though the Redhead breeds in small numbers along the coast and at the Salton Sea, summer records in between are very rare. Jim Wilson found three at Tule Lake (T27) on 6 June. On the 27th, the Redheads had been replaced by three Northern Shovelers, equally unexpected in the area in summer. Another odd summer duck record was Claude Edwards' of a Bufflehead at Big Laguna Lake (O23) on 2 June.

The Sora that Lori Hargrove encountered on the San Luis Rey River near Indian Flats (D19) on 2 June was completely unexpected because this species' breeding range long ago retracted entirely out of southern California. Robert Patton, Joe Barth, and I were delighted to find a family of Spotted Sandpipers with two downy chicks at the south tip of El Capitan Reservoir (O16) on 9 July. The species has been confirmed breeding at only three other locations in San Diego County, and this is the southernmost for it anywhere, although we have records of the birds summering but not confirmed breeding at several other locations. After their nesting attempt at Kendall-Frost Marsh (Q8) got flooded out last year, Forster's Terns persevered and enjoyed success this year. Robert Patton observed adults feeding well grown chicks in the marsh on 10 July.

The Inca Dove is gradually extending its range, becoming much more numerous in the Imperial Valley in the past decade. But it was quite a surprise when Jack Schlotte found one singing incessantly ("no hope!") in our yard in the Hillcrest neighborhood of San Diego (R9) on 1 June; it stayed until the 9th. One of the summer's most exciting discoveries, by Terri Gallion and Paul Jorgensen, was of a Yellow-billed Cuckoo along San Felipe Creek above Scissors Crossing (J22) from 6 to 12 July. The bird's behavior suggested it was an unmated male, but establishment of a population has to start with a single bird. The area's recent acquisition by Anza-Borrego Desert State Park means that long-term development of the extensive mature riparian woodland required by cuckoos is now possible. Pierre Howard reported a vagrant in the Tijuana River valley (W10) on 28 June.

Ken Weaver saw three Black Swifts circling the summit of Hot Springs Mt. (E20) on 8 June. Could the mountain's steep slopes conceal a waterfall offering these birds a nest site, giving us another new nesting species for the county? The nearest known sites for the Black Swift are near Idyllwild in the San Jacinto Mountains. Ken also encountered Calliope Hummingbirds, one on Hot Springs Mt. (E21), where there is a previous record of a displaying pair, on 18 May, and two in Agua Tibia Canyon (D12) on 18 June. Though the birds in Agua Tibia Canyon were at only 2000 feet elevation, the canyon is so deep that parts remain in shade until 11 AM and other mountain birds like Olive-sided Flycatchers and Western Tanagers summer at lower elevations than any other location known in San Diego County. Bill Haas followed the success of a nesting pair of the Hairy Woodpecker at 2470 feet elevation along the San Luis Rey River (F16)—two young fledged from a hole in a sycamore snag in the third week of July, an interesting complement to information on this species' nesting reported in the last Wrenderings.

Good news for the endangered Willow Flycatcher is three new nesting locations discovered this year. Ken Weaver found two carrying insects in a boggy glade in Agua Tibia Canyon on 17 July. Joe Barth found the nest of a pair along Cedar Creek in William Heise County Park (L20) on 10 July. And Barbara Kus and her team found a colony of four pairs along the San Diego River above El Capitan Reservoir (N16/N17), a site with enough habitat to support a growing population.

A few Clark's Nutcrackers apparently went south of the border after last winter's incursion and didn't head back north until June. I was startled to see four in Lark Canyon (S26) on the 9th, and Ed Hall and Jim Zimmer encountered one near Julian (J20) on the 15th. Brennan Mulrooney found up to two singing Swainson's Thrushes along the Tijuana River (W10) on 30 June and 2 July, a southward extension of the summer range of a riparian species never known to nest in Mexico. Brennan also reported the first confirmation of Swainson's Thrush breeding in southern San Diego County since 1997 with one carrying berries along the San Diego River in Santee (P12) on 4 July. The Gray Catbird discovered by Richard Webster at Cabrillo National Monument 28 May-2 June was only the third reported in San Diego County in spring.

Mountain Chickadees nested outside their previously known range at two spots where they had been seen repeatedly in the winter. Ed Hall saw one carrying food items in Vista (G8) on 21 May, while Rich & Susan Breisch found a pair feeding nestlings in a birdhouse in Live Oak Springs (S25) on 9 June. Geoff Rogers noted a Fox Sparrow in the Deer Park area of the Laguna Mts. on 30 June, only the second record of this species summering in the Lagunas.

The Brewer's Sparrow nest in Ranchita (H21) failed, unfortunately, but the birds enjoyed success in McCain Valley (R26). Joe Barth followed on his observation of 17 May with another visit on 11 June, discovering two fledged juveniles at the same location where he had seen an adult carrying a food item. I returned with Joe on the 13th and we saw the young again, confirming the first successful nesting of Brewer's Sparrow in San Diego County and the southernmost of the species ever.

The Summer Tanager continues to colonize San Diego County. Paul Jorgensen found they returned to San Felipe Creek around Scissors Crossing in numbers similar to last year's, and found two new pairs on Banner Creek (K21) on 16 July. Ken Weaver found up to four in a day (24 July) along the Santa Margarita River near Fallbrook (C8) and believes there may be as many as five pairs with at least two feeding young. Ken found another pair in Agua Tibia Canyon, Lori Hargrove found one bird in Borrego Palm Canyon (F23), and Joe Barth another in the Manzanita Indian Reservation (R25). Vagrants more likely of the eastern subspecies reached the coast, with sightings at Point Loma, National City, and Imperial Beach.

Up to 3 Rose-breasted Grosbeaks in a day were at Point Loma from 4 May through 7 June and showed up at other locations too numerous to list. Lazuli Buntings were unusually numerous and accompanied by a generous sprinkling of Indigos, leading to hybridization. Jim Wilson heard a "mystery bird" singing insistently near Warner Springs (F19), so Mary Beth Stowe and I followed up on 28 June, finding the bird was a male Indigo with a partly white belly, a pure Lazuli as a mate, and a clearly hybrid fledgling (underparts streaked more heavily than in any pure Lazuli). Mary Beth and I had another male Indigo in Peutz Valley near Alpine (P16) calling agitatedly, and Claude Edwards found a female Indigo with fledglings near Cibbets Flat (Q23)—and only male Lazulis as prospective mates. Several other of the Indigo Buntings observed were paired with Lazulis and likely hybridized as well.

San Diego County's only Yellow-headed Blackbird colony, at Tule Lake, enjoyed success again this year. Jim Wilson estimated 50 birds on 6 June, up from last year's 20. A more stealthy colonist from the southeast, the Bronzed Cowbird, appeared again in the northern Borrego Valley (E24), where Paul Jorgensen saw one on 21 May.

The spring of 2001 was a faint echo of 1992 in bringing us vagrants from the southeastern United States. The Yellow-throated Vireo found by Brennan Mulrooney in Pine Valley (P21) on 11 June remained to the 16th. Todd Pepper discovered another at Old Mission Dam (P11) 20-21 June. The three southeastern warblers participating in this pattern are the Parula (at least 8 reported), Hooded (at least 6), and Kentucky (Brennan Mulrooney found one at Fort Rosecrans Cemetery on 22 May). The Parulas included three singing but unmated males maintaining territories monitored by Bill Haas along the San Luis Rey River about 1 mile southeast of the Forest Service picnic area (G16). The more northern warblers, far more frequent 25 years ago that the southeastern species, are now lagging. From Point Loma, Richard Webster reported a Tennessee on 28 May and a Magnolia on 6 June, Matt Farley a Chestnut-sided 22-23 May. In the desert, Mel Gabel encountered a Chestnut-sided at Lower Willows, Coyote Creek (D23), on 19 May, Bob Thériault a Black-and-white on Villager Peak (C27) on 17 June. Perhaps the strangest warbler observation, though, was Bill Haas' of two Townsend's Warblers singing near the Parulas along the San Luis Rey River 16-23 June, long after they should have been in the Pacific Northwest.

Sketches from Key to North American Birds, Elliott Coues and
History of North American Birds, Spencer Baird, Thomas Brewer and Robert Ridgway

--Philip Unitt

birdatlas@sdnhm.org