Charles T. Collins

Estimated population size of the Island Scrub-Jay Aphelocoma insularis

Summary As an island endemic, the Island Scrub-Jay’s Aphelocoma insularis population status and conservation are of concern. In addition, because the Island Scrub-Jay is easily observed, it is an ideal candidate for monitoring the effects of management efforts on Santa Cruz Island, California. We used estimates of territory size in several different habitats occupied by the Island Scrub-Jay and the total area of these habitats on the island to develop an empirical estimate of the population size for this species. Our most conservative, and we feel most realistic, estimate for the Island Scrub-Jay breeding population is 7,000 individuals and for the non-breeding population 5,500 individuals, yielding a total population estimate of 12,500. Even though conservative, this estimate is larger than earlier estimates of 4,000 to 6,000 individuals. Even so, our data suggest no reason exists for immediate concern regarding the population viability of the Island Scrub-Jay and they provide a baseline for future estimates and comparisons. Most importantly, this population estimate can be used to monitor the influence on the Island Scrub-Jay of future island management efforts, especially regarding exotic tree species and feral pigs.

Food of the Little Swift Apus affinis and African Black Swift Apus barbatus in South Africa

The food habits of the Little Swift Apus affinis and African Black Swift Apus barbatus were quantified at Kimberley, Northern Cape province and Makapansgat, Limpopo province, South Africa. As previously documented for other species, both of these swifts took a wide variety of aerial arthropods including spiders as well as 10 orders and 64 families of insects in the combined samples. Little Swift prey items at Kimberley averaged 3.2 mm in body length (SD = 1.6, n = 2 178) and ranged from 1.2 to 16.0 mm. Prey items of African Black Swifts at Kimberley averaged 4.4 mm (SD = 4.1, n = 185) with a range of 0.9 to 15.9 mm, and 2.8 mm (SD = 0.8, n = 2 099) at Makapansgat with a range of 1.2 to 10.8 mm. At Kimberley, African Black Swifts took more (8.3%) larger prey items (>8 mm), such as termites, than Little Swifts (2.3%). As also true of other swifts, both African Black Swifts and Little Swifts took a majority (>90%) of smaller prey items that are abundant in the air column. Mean prey size is significantly correlated with predator body size in Apus and Tachymarptis swifts.

Notes on the Breeding Biology of the White-Throated Swift in Southern California

Abstract Reproductive activities of White-throated Swifts (Aeronautes saxatalis) were examined from 1997 to 2006 at two nest sites in a human-made structure in southern California. The start of egg-laying was from 27 April to 30 May and hatching of the first chick ranged from 21 May to 23 June; all chicks had fledged by late July, 42–43 days after hatching. The annual molt of adults began in early June and broadly overlapped with the chick-rearing period. Year to year adult survival was minimally 73.9% and nesting pairs showed strong mate and nest site fidelity; pairs reused nests up to five consecutive years. The composition of the arthropod food (insects and spiders) brought to nestlings was different in the periods 1997–2000 and 2001–2004 but prey size was similar in both periods. The onset of breeding was more varied from year to year than the start of the primary feather molt suggesting differing environmental stimuli for these important components of the annual cycle.

Interspecific Kleptoparasitism of Elegant Terns by Snowy Egrets

Abstract Snowy Egret (Egretta thula) kleptoparasitism of Elegant Terns (Thalasseus elegans) at a southern California breeding colony entailed piracy of fish from recently fed chicks, adults feeding chicks and adults engaged in courtship feeding.

Molecular systematics of swifts of the genus Chaetura (Aves : Apodiformes : Apodidae).

Phylogenetic relationships among swifts of the morphologically conservative genus Chaetura were studied using mitochondrial and nuclear DNA sequences. Taxon sampling included all species and 21 of 30 taxa (species and subspecies) within Chaetura. Our results indicate that Chaetura is monophyletic and support the division of the genus into the two subgenera previously identified using plumage characters. However, our genetic data, when considered in combination with phenotypic data, appear to be at odds with the current classification of some species of Chaetura. We recommend that C. viridipennis, currently generally treated as specifically distinct from C. chapmani, be returned to its former status as C. chapmani viridipennis, and that C. andrei, now generally regarded as synonymous with C. vauxi aphanes, again be recognized as a valid species. Widespread Neotropical species C. spinicaudus is paraphyletic with respect to more range-restricted species C. fumosa, C. egregia, and C. martinica. Geographically structured genetic variation within some other species of Chaetura, especially notable in C. cinereiventris, suggests that future study may lead to recognition of additional species in this genus. Biogeographic analysis indicated that Chaetura originated in South America and identified several dispersal events to Middle and North America following the formation of the Isthmus of Panama.