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Indigo Bunting
Passerina cyanea

In the 1960s the Indigo Bunting was just another vagrant from the eastern United States. But the front of its expanding breeding range has now almost reached the Pacific coast. Today this brilliant bird, though still rare, is becoming ever more frequent as a summer visitor to San Diego County's inland valleys and foothills. A noticeable upswing in occurrences coincided with the arrival of the new millennium.

Breeding map of Indigo Bunting
Indigo Bunting Breeding Season
Dark green: Breeding confirmed
Light green: Breeding probable
Pale yellow: Breeding possible
Single shading: Presumed migrants only

Breeding distribution: The Indigo Bunting is a recent colonist in San Diego County, as elsewhere in southern California (Rowe and Cooper 1997). Until 2002, all known nestings were of mixed pairs, Indigo and Lazuli, or, the identity of the female was ambiguous. The first likely hybridization took place in Spring Canyon (P11) in 1973, when the male Indigo was seen paired with a female Lazuli 2-10 June and the female was later seen with fledglings (P. Unitt, AB 29:920, 1973). Since then, summer records have become ever more frequent, too frequent to list individually. Subsequent records of apparent or definite breeding have been 22 May-3 July 1991 near Lake Cuyamaca, where a male Indigo was paired with Lazuli Bunting and feeding fledgling on latter date (R. Ford, C. G. Edwards, AB 45:1162, 1991), 28 May 1993 near Ramona, where a male was paired with female Lazuli (C. G. Edwards, AB 47:1151, 1993), 16 July 2000 at Pine Hills (K19), where an unidentified female and/or juvenile bunting were near a male Indigo (J. R. Barth) and 21 June 2001 in Peutz Valley (P16), where a male was calling agitatedly as well as singing territorially (M. B. Stowe, P. Unitt). On 24 June 2001, along Kitchen Creek near Cibbets Flat (Q23), an agitated female Indigo, with male Lazuli Buntings singing nearby, had two probable fledglings (C. G. Edwards). On 28 June 2001, in Cañada Verde near the Warner Springs fire station (F19), an apparent first-year male Indigo (some irregular white on belly) was associated with a female Indigo and a hybrid fledgling (streaking heavier than in a juvenile Lazuli; M. B. Stowe, P. Unitt). On 13 July 2001, near the confluence of San Felipe and Banner creeks (J22) a male Indigo was paired with a female Lazuli, and a mixed pair nested twice at the same site in summer 2002 (J. R. Barth), the first apparent return of an Indigo, another step toward establishment of a population. Outside the Lazuli Bunting's observed breeding range, a male Indigo at Jacumba (U28) 28 June-1 July 2000 was paired with an ambiguous female; she was with a fledgling on the first date and went into a copulation-solicitation posture when the male few over her on the latter date (J. K. Wilson, P. K. Nelson, P. Unitt).

Though records of territorial Indigo Buntings are still scattered, they range from the inland valleys to the desert edge and exclude the coastal strip and the desert floor. The birds' habitat is not too specialized: riparian woodland and edges, oak woodland edges, and even an abandoned avocado orchard.

Nesting:Like the Lazuli, the Indigo Bunting places its nest in dense low often thorny vegetation, usually within 1 meter of the ground. The nest is screened from above by leaves (Payne 1992). A female Indigo paired with a first-year male Indigo was building a nest, later abandoned, near Scissors Crossing (J22) on 7 July 2002 (J. R. Barth). The nest was about 2 feet off the ground in a thicket of mugwort, Artemisia douglasiana.

Migration: In San Diego County, the Indigo Bunting has been recorded primarily from mid May through July, when the males stop singing. From 1997 through 2001 the earliest date was 12 May (2001, one at Lower Willows, D23, B. Peterson; one in Los Peñasquitos Canyon, P. Lovehart). Records as early as 11?12 April (1992, one at Point Loma, S7, G. McCaskie, AB 46:482, 1982) and 15 April (1987, one at Vallecito, B. Andeman, AB 41:490, 1987) are exceptional. Spring vagrants may be seen at least as late as 21 June (1997, one at Widman Park, S11, P. Unitt). The latest summer record is of an adult male in the Tijuana River valley on 7 August 1976 (G. McCaskie). The Indigo Bunting is now more frequent in spring and summer than in fall but still occurs regularly as a vagrant in September and October, exceptionally as late as 22 November (1975, Balboa Park, J. L. Dunn).

Winter distribution: Still only two records, of one in Balboa Park 10-23 December 1967 (AFN 22:480, 1968) and one in San Marcos 9 March 1976 (AB 30:770, 1976).

Status: Despite heavy cowbird parasitism in its breeding range, being trapped as a cage bird in its winter range, and failing to adapt to urbanization anywhere (Payne 1992), the Indigo Bunting continues to spread.

Taxonomy: A borderline case as species or subspecies, the Indigo and Lazuli Buntings hybridize wherever they occur together. Yet differences in song, molt, females' mate preference, and the persistence of the parental phenotypes in the zone of overlap imply that mechanisms isolating the two have taken hold.

Literature Cited

Greene, E., Muehter, V. R., and Davison, W. 1996. Lazuli Bunting, in The Birds of North America (A. Poole and F. Gill, eds.), no. 232. Acad. Nat. Sci., Philadelphia.

Payne, R. B. 1992. Indigo Bunting, in The Birds of North America (A. Poole, P. Stettenheim, and F. Gill, eds.), no. 4. Acad. Nat. Sci., Philadelphia.

Rowe, S. P., and Cooper, D. S. 1997. Confirmed nesting of an Indigo with a Lazuli Bunting in Kern County, California. W. Birds 28:225-227.