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

WRENDERINGS
Notable Observations
Summer 1999

I hope that all of you have been enjoying the spectacular waves of landbird migration that began in the last week of April as well as observing breeding birds. The concentration of migrants this year is greater than anything I have experienced since the 1970s. Especially interesting were my trips to unadopted squares H22 and R27 at the edge of the Anza-Borrego Desert. Early in the mornings I saw an almost continuous stream of migrants—Black-headed Grosbeaks, Lazuli Buntings, Western Kingbirds, and warblers—flowing up and out of the desert, heading almost due west just over the tops of the chaparral shrubs. The low elevation of the mountain crest in much of San Diego County may put us on the energy-efficient route for migrating from western Mexico to northern California and the Pacific Northwest.

The Fork-tailed Storm-Petrel is a very rare and irregular visitor to the ocean off San Diego, with none reported earlier this year, so it was a surprise when Brian Foster found two dead on the beach, one at the mouth of Aliso Creek (F4) on 1 May, the other on the Silver Strand (T9) on 7 May.

The Brandt's Cormorant colony on the cliffs at La Jolla (P7) is active this year with 4 occupied nests noted by Leslie Polinsky on 24 April, and the Double-crested Cormorant colony at the east end of Sweetwater Reservoir (S13) is too, with 28 occupied nests counted by Pete Famolaro on 15 April.

The Reddish Egret wintering on San Diego Bay stayed at least until 4 April, when Bill Haas saw it in the Paradise Marsh, National City (T10). The Yellow-crowned Night Heron, now 18+ years old, continues to associate with the colony of the Black-crowned Night Herons on the grounds of Scripps Institution of Oceanography (O7).

Our atlas effort is revealing the Turkey Vulture as widespread and probably nesting in the rocky hills of the Anza-Borrego Desert. Lori Hargrove noted three juveniles, probably recent fledglings, west of the Elephant Tree area in square K28 on 4 May, and Dave Seals encountered a remarkable concentration of 55 within a mile of a dead coyote along Highway S2 in Vallecito Valley (M24) on 30 April, probably too late in the spring for migrants.

Paulette Ache noted Borrego Springs' (G24) first White-fronted Goose on 28 March, then a flock of 31 migrant Brant there on 19 April.

The pair of Ospreys that built a nest on a floodlight at Scripps Ranch High School (N10) came back this year for another attempt, this one successful—San Diego County's second successful Osprey site. Gerard and Anja Kroon saw the pair copulating on 30 January, then Bert McIntosh noted them feeding young on 5 May.

In addition to scattered individuals, two substantial flocks of migrating Swainson's Hawks were seen this spring, one of 74 along San Felipe Creek just northwest of Scissors Crossing (J22) by Pat Dunn and Cyndi Smith, park naturalists from Canada, on 18 March, and another of 24 in the northern Borrego Valley (E24) by Mark & Leslie Polinsky on 29 April.

The wintering Zone-tailed Hawk freeloading on trapped gophers at Oak Hill Cemetery, Escondido (I12), was last noted by Christine Rideout on 13 March. Then Conrad Sankpill noted one along Nate Harrison Grade, Palomar Mountain (E13), on 17 April. Could the steep slopes in this area conceal a Zone-tail's nest?

The Black Oystercatcher is only an erratic visitor to our rocky shoreline so is always an exciting discovery. Frances Shaw noted two at La Jolla on 27 April. The Solitary Sandpiper is rarely seen in spring migration so two in close succession were a surprise. Fred Sproul found one in northwest Ramona (K13) on 24 April, then Lori Hargrove found another in a pond along the Pacific Crest Trail north of the intersection of highways S2 and S22 (G20) on 27 April.

The Burrowing Owl continues to be the county's most alarmingly decreasing breeding species. The only reports so far this spring are from northeast Borrego Springs (F25) by Paulette Ache. She found five owls at active burrows on 1 March but by 11 April the burrows had all been dug out by coyotes or dogs and the birds were gone.

Ken Weaver made our most positive identification of the Pygmy Owl yet when he had one respond to a tape recording near High Point of Palomar Mountain (D15) at 7:07 PM (sun still up) of 13 May. Though the bird remained concealed behind a scrub oak, its call was slower and lower-pitched than that of the Saw-whet, familiar to Ken and fairly common on Palomar—he had 5 Saw-whets in the same area later that evening. This observation gives some context to Betty Siegel's probable Pygmy Owl call in Cuyamaca State Park (N20) on 30 January 1988—it too was calling in the late afternoon. The Saw-whet is strictly nocturnal.

The unsettled weather that made Vaux's Swift migration so conspicuous this year also brought two sightings of the rare Black Swift, two along the Santa Margarita River north of Fallbrook (C7) on 24 April by Ken Weaver and one near the intersection of Interstate 805 and Miramar Road on 30 April by Bill Haas.

Except at Butterfield Ranch (M23), where Mary Beth Stowe and Phil Nelson had up to four on 16 and 17 April, the Vermilion Flycatcher is very rare and irregular in San Diego County, especially in the breeding season. Its population throughout Southern California has shrunk to just a few tiny remnants. So three found by Paulette Ache on the Ellis Ranch (F25) near Borrego Springs, the pair found by Patricia Nance and Nicole Perretta along the Sweetwater River in the Jamacha area (R14), and the single singing male found by Geoff Rogers in McCain Valley (S26) are noteworthy and encouraging.

In addition to those discovered during our Oak Grove blockbuster, three new sites for the Gray Vireo have come to light this spring. Ken Weaver had three along Oak Grove Truck Trail on Palomar Mt. (D15) on 14 May, giving more context to the one Joe Barth and Bryan O'Leary found on Aguanga Ridge during the blockbuster. The other new sites are southeast of the previously known range: Lori Hargrove had one singing in Lost Valley (R26) near McCain Valley Road on 11 May, and Jim Wilson had another in the extreme southeast corner of the county (U29) on 27 April. Both Jim and Lori are very familiar with the Gray Vireo since their adopted squares Q22 and R23 have the county's greatest known concentration of the species.

Claude Edwards found a Winter Wren in Warner Springs (F19) on 3 May. This species is known in San Diego County as a rare fall and winter visitor but had never before been reported in spring.

Bendire's Thrasher had been found in winter in coastal San Diego County only seven times before Susan Breisch saw one near the SW tip of Sweetwater Reservoir (T12) on 6 March.

After our scattered sightings of Purple Finch during the breeding season near Valley Center last year, Ken Weaver discovered the species along De Luz Creek (C6), counting four territorially singing males on 1 May, another remarkable extension of this typically mountain species at low elevation. For some regional context, another lowland report, of one feeding a fledgling in riparian forest in the Prado Basin near Corona, Riverside County, merited publication in the latest Field Notes.

Bill Haas noted a White-throated Sparrow, rather late and in atypical habitat, in brush adjacent to the Paradise Marsh in National City on 4 April.

The Kentucky Warbler found by Pete Ginsburg in a tiny patch of riparian habitat in southwest Vista (I7) on 15 March made a first winter record for this species in San Diego County—the date is too early for a spring migrant.

Unusually large numbers of Yellow-headed Blackbirds have shown up this spring, with up to 13 at Agua Caliente County Park (M26, Dave Seals), 20 in Borrego Springs (G24, Paulette Ache), and 20 in southwest Ramona (L14, Fred Sproul). Some have been at sites suitable for breeding, still unproven for this species in San Diego County. If you see Yellowheads hanging around a marsh, visit the site repeatedly to check for this possibility.

A few eastern vagrants have shown up already this spring, before their probability peaks in early June. Mary Beth Stowe encountered a Gray Catbird, never before recorded in the county in spring, in San Clemente Canyon (P8) on 27 April, and Robbie Fischer passed on a second-hand report of one by Randy Moore along the Santa Margarita River in Camp Pendleton (G5)—let's hope he sends an adequate report to Guy McCaskie to support a record in Field Notes, essential for substantiating any vagrant. Sue Smith found a Red-eyed Vireo along the Guy Fleming Trail in Torrey Pines State Reserve (N7) on 6 May; this species had been found only three times previously in the county in spring, and it is much less frequent even in fall than 30 years ago, possibly reflecting a general population decline. Two more frequent spring visitors are Geoff Rogers' N. Parula in Sycamore Canyon at the east end of Marine Corps Air Station Miramar (O12) on the same day and Mark Jorgensen's Black-and-white Warbler at Vallecito Stage Station (M25) on 12 May.

--Philip Unitt

birdatlas@sdnhm.org

Redhead chick sketch by Nicole Perretta

Summer 1999 Wrenderings | Wrenderings Archive | Bird Atlas Introduction