Variation in incubation length and hatching asynchrony in Eastern Kingbirds: Weather eclipses female effects

Incubation length and hatching asynchrony are integral elements of the evolved reproductive strategies of birds. We examined intra- and interpopulation variation in both traits for Eastern Kingbird (Tyrannus tyrannus) populations from New York (NY), Kansas (KS), and Oregon (OR) and found that both incubation length and hatching asynchrony were not repeatable among females, after controlling for a repeatable trait, clutch size. Instead, incubation length and clutch size were influenced by ambient temperature and precipitation. Incubation length exhibited the same median (15 days) and range (13–17 days) at all sites. Model selection results indicated that incubation periods for the smallest and largest clutches were longer in NY than KS when rain was frequent throughout incubation, in replacement nests, and likely when ambient temperatures were low during egg-laying. Full hatching usually required 2 days (but up to 3), with synchronous hatching associated with small clutch sizes, short incubation periods, frequent rain during the egg-laying period, and low ambient temperatures during the first half of incubation. Nestling starvation was uncommon (5–9% of nestlings monitored) and not associated with greater hatching asynchrony. These results indicate that while clutch size, a repeatable female trait, contributed to variation in incubation length and hatching asynchrony in Eastern Kingbirds, weather was a greater source of variation, especially for incubation length.

Reproduction of the Atlantic Forest endemic star-throated antwren, Rhopias gularis (Aves: Thamnophilidae)

The Thamnophilidae are one of the most speciose Neotropical bird families, yet aspects of their natural history remain poorly documented. Here we provide information on breeding phenology, the length of incubation and nestling periods, parental care, and nesting success of the Star-throated Antwren, Rhopias gularis, an Atlantic Forest endemic. The data are discussed in light of life history theories. We found 27 active nests during two breeding seasons (2013/2014 and 2014/2015) at Carlos Botelho State Park in southeastern Brazil. Nesting activities were observed from September to January. Incubation and nestling periods lasted 16.8 ± 0.6 and 11.0 ± 0.86 days, respectively, as with most other antbirds. Males and females shared equally in incubation and nestling provisioning. The small clutch size of two eggs is that most commonly found in tropical birds and is hypothesized to have evolved due to increased nest predation rates. However, our data was not consistent with this hypothesis as the nest survival probability was high (57%). This is one of only a handful of studies that provide comprehensive information on the breeding biology of a Thamnophilid species in undisturbed habitat.

Biometry, production potential and genetic characterization of Red Jungle Fowl (Gallus gallus) reared under captivity from western Himalayan state of Himachal Pradesh, India

The present investigation was conducted to study the morphology, production potential and genetic architecture of Red Jungle Fowl (Gallus gallus) kept in captivity. Records of 104 birds of RJF (65 males and 39 females) were utilized in study. Males had prominent plumage pattern with neck hackles, greenish black tails, and prominent bright red single comb, while females were comparatively smaller with very small combs. RJF are seasonal breeder having small clutch and egg size. Observed and effective number of alleles across the microsatellite loci varied from 5-18 with an overall mean of 10.28 and 5.04, respectively. The average expected heterozygosity and observed heterozygosity were 0.492 and 0.758 respectively. Study revealed existence of population structure accompanied by higher inbreeding along with sufficient heterozygosity. The effort must be directed to introduce unrelated typical RJF in to the present population to maintain heterozygosity and ensure conservation of unique germplasm.

Parasite infestation and predation in Darwin's small ground finch: contrasting two elevational habitats between islands

Contrasting ecological conditions may affect the distribution, abundance and impact of parasites and predators throughout the ranges of hosts and prey. Such patterns are evident on the archipelagos of Hawaii and the Galapagos, which vary in their distribution and abundance of avian parasites within and across islands. Previous research has documented higher intensity of parasitic fly larvae (Philornis downsi) in nests of Darwin's finches on elevated islands of the Galapagos. Here we examine P. downsi intensity and predation in 71 nests of Darwin's small ground finch (Geospiza fuliginosa) on Floreana Island. We found significant differences in parasite intensity, nest predation and clutch size between the lowland (0–100 m) and highland (300–400 m) habitats. Lowland finch nests had few P. downsi parasites (mean of 8 per nest), high nest predation (44% of nests) and large clutch size (3.4). Highland finch nests showed the opposite pattern, with many P. downsi parasites (40 per nest), low nest predation (17%) and small clutch size (2.5). This study suggests that the impacts of an introduced parasite are limited by its niche requirements and resource availability within and across islands. Our findings also imply that the vulnerability of bird populations to introduced parasites and predators is linked with variation in life history strategies across habitats.

Laying-Stage Nest Attendance and Onset of Incubation in Prairie Nesting Ducks

We used microprocessor data loggers to document patterns of nest attendance during the laying stage and to quantify temperatures of dummy eggs during laying for Mallard (Anas platyrhynchos), Blue-winged Teal (A. discors), Northern Shoveler (A. clypeata), Northern Pintail (A. acuta), Gadwall (A. strepera), Green-winged Teal (A. crecca), American Wigeon (A. americana), and Lesser Scaup (Aythya affinis) nesting in southern Manitoba in 1994 and in northeastern North Dakota in 1995–1997 and 2000–2002. Females of all species increased the time they spent on the nest as laying progressed, but species differed in their pattern of increased attendance. Female Blue-winged Teal and Northern Shoveler that laid smaller clutches increased the time they spent on the nest more rapidly than conspecifics that laid larger clutches, but large- and small-clutch conspecifics had similar attendance at the end of the laying period. Attendance during laying was not influenced by low ambient temperature, precipitation, or nest initiation date. For all species combined, maximum egg temperatures increased as laying progressed. Eggs were heated to temperatures sufficient for embryonic development as early as the day that the second egg was laid. Our findings contradict the prevailing paradigm that incubation in waterfowl begins after clutch completion and raise questions about how hatching synchrony is achieved. We relate our findings to two hypotheses (nutrient limitation and viability–predation) that have been proposed to explain the limits to clutch size in ducks.