Climate as an Evolutionary Driver of Nest Morphology in Birds: A Review

Avian nests are critical for successful reproduction in birds. Nest microclimate can affect egg development, chick growth and fledgling success, suggesting that nest building behavior should be under strong selective pressure to nesting conditions. Given that the internal microclimate of the nest is critical for avian fitness, it is expected that nest morphology is shaped by the local environment. Here we review the relationship between nest morphology and climate across species’ distributions. We collate growing evidence that supports a link between environmental conditions and particular nest traits, within species and across species. We discuss the degree to which phenotypic plasticity in nesting behavior can contribute to observed variation in nest traits, the role of phylogenetic history in determining nest morphology, and which nest traits are likely to be influenced by climatic conditions. Finally, we identify gaps in our understanding of the evolution of nest morphology and suggest topics for future research. Overall, we argue that nests are part of the extended phenotype of a bird, they play a crucial role in their reproductive success, and may be an important factor in determining which species will be able to persist in the face of ongoing climate change.

Age and experience affect the reproductive success of captive Loggerhead Shrike (Lanius ludovicianus) subspecies

Two explanations are often used to interpret the positive relationship between reproductive success and age: (1) trade-offs between current and future breeding and (2) age-related improvements in competence. Captive populations provide a unique opportunity to test these explanations because several mechanisms that result in age-related improvements in competence are managed. We modelled the effect of age and experience on the reproductive success of captive migrant Loggerhead Shrike (Lanius ludovicianus L., 1766) subspecies (formerly Lanius ludovicianus migrans W. Palmer, 1898). Female shrikes had the highest reproductive success during mid-life and lower success at 1–2 years of age and over 10 years. Both experienced male and female shrikes had higher fledgling success than inexperienced individuals. Although captive populations breed in controlled settings with few limitations, this work suggests that both explanations (i.e., trade-offs and age-related improvements in competence) are important for understanding reproductive success. Furthermore, management of the captive shrike population can be informed by these relationships to maximize the number of young produced for release to supplement the wild population.

The breeding biology of the Forest Red-tailed Black Cockatoo Calyptorhynchus banksii naso Gould in south-western Australia. II. Breeding behaviour and diet

Little is known of the breeding behaviour of the Forest Red-tailed Black Cockatoo Calyptorhynchus banksii naso (FRTBC), a large, iconic forest cockatoo, endemic to the south-west corner of Western Australia, currently listed as Vulnerable under the State Western Australian Wildlife Conservation Act and under the Commonwealth Environment Protection and Biodiversity Conservation Act. In this paper, we provide details of breeding behaviour of FRTBC based on observations throughout the year over 17 years, together with observations of diet and feeding behaviour over the same period. FRTBC are monogamous hollow-nesters. Breeding was recorded in all months, with peaks in autumn-winter (April– June) and spring (August–October), with few records in January and February. Breeding also varied between years, with little breeding in 1999, 2001 and 2008, but many observations in 2006 and 2009. Breeding occurred at times of fruiting of either of the principal feed trees, Jarrah Eucalyptus marginata or Marri Corymbia calophylla, so it does not depend solely on one or the other of these species. Courtship displays were noted at all times of the day, from before dawn at roost sites to dusk. In total, 205 breeding events were recorded, of which 69 (93%) of 72 nests had breeding confirmed on a second visit. Use of particular nest hollows varied considerably, with some used only once and some up to seven times. Only one egg is laid, which the female incubates for 29 to 31 days, before a nestling hatches weighing between 27 and 32 g. The female remains in the hollow during incubation and only leaves for a short period in the evening to be fed by the male, usually at dusk. The chicks are brooded for up to 10 days, after which the female leaves the nest between dawn and dusk. Pairs of birds appear to recognise each other by calls, not responding to calls by others in the area. Chicks only respond when the parent is heard. Chicks are fully feathered at 48 days. Fledgling success was estimated at 60%. Juveniles remain dependent on the adults 18 months to 2 years. Thirty-seven chicks were banded between 1997 and 2011. Juvenile-immature birds moved on average less than 3 km from their natal tree and older birds were observed moving up to 19 km. This suggests that FRTBC are generally sedentary. Immature birds took up to three times as long as their parents to open Jarrah or Marri nuts and eat the seeds. In recent years there has been an interesting change in foraging behaviour of birds in the northern Darling Range (adjacent to the Perth metropolitan area) with the FRTBC discovering and using a new food source, the introduced Cape Lilac Melia azedarach, and this species is of growing importance as food in the Perth region. In combination, the data on breeding biology and diet highlight the importance of identifying recruitment rates and food availability in managing populations of FRTBC.

Poorer breeding by little penguins near Perth, Western Australia is correlated with above average sea surface temperatures and a stronger Leeuwin Current

Using 20 years of data (1986 to 2008), we examined relationships between oceanographic variables (Fremantle sea level (FSL) – a proxy for the strength of the Leeuwin Current – and sea surface temperature (SST)) and five measures of little penguin, Eudyptula minor, breeding performance near Perth, Western Australia: namely (1) the laying date, (2) the number of chicks produced per pair, (3) the proportion of eggs that hatched, (4) the overall breeding success, defined as the proportion of total eggs laid that resulted in successful fledglings and (5) chick mass at fledging. The next three years of data (2009 to 2011) were used to test the performance of our statistical predictive models. FSL provided more accurate predictions of timing of laying, whereas SST provided more accurate predictions of breeding success. A later end to laying was associated with a high FSL during the summer (December to February) before breeding. Higher SSTs in the pre-breeding period from April to May corresponded to reduced breeding success, with lower fledgling success, fewer chicks per pair and generally a lower mean mass of chicks at fledging. The models predict that future oceanographic warming is expected to reduce the breeding success of this colony of little penguins.

Drought Induced Nepotistic Behaviour in Indian Black Ibis (Pseudibis papillosa) Inhabiting the Arid Zone of Rajasthan, India

Drought induced nepotistic behaviour in the Indian Black ibis (Pseudibis papillosa) inhabiting the arid zone of Rajasthan has been studied. The aim of the present study is to know about any breeding abnormalities induced in the Indian Black ibis by seasonal tragedy like drought. As such the nepotistic behaviour is not found in the Black ibis (Pseudibis papillosa) during normal season. Drought induces a reduced nesting activity and nepotistic behaviour in the Black ibis inhabiting arid zone. The helper birds (Non breeding birds of the own species) become active during drought to assist breeding pairs of Black ibis in various reproductive activities like feeding of breeding female, nestlings, fledglings and defending the nests. The role of helpers in breeding activities of Black ibis during drought also improves their clutch size, hatching success and fledgling success. The significance of the drought induced nepotistic behaviour in Black ibis in view of Hamilton’s theory of kin selection has been discussed.Keywords: Nepotistic behaviour, Black ibis, arid zone, Rajasthan, Indiadoi: 10.3126/on.v6i1.1654Our Nature (2008)6:47-51

Distribution and Abundance of Spotted Owls in Zion National Park

The main objective of this study is to estimate the distribution, habitat use, and reproductive status of Mexican spotted owls (Strix occidentalis lucida) in Zion National Park. This information will allow managers to coordinate park activities that potentially conflict with nest sites, roost sites, or brood rearing habitats. Other objectives of this study are to estimate spotted owl food habits and fledgling success, and to compare these findings with other North American spotted owl populations.

Seasonal reproductive changes in the American robin (Turdus migratorius L.) of the Pacific Northwest

Gonadal analysis of the American robin of southwestern British Columbia indicates that males progress rapidly into breeding condition after mid-March. Females respond more slowly but before mid-April may be laying eggs. Males begin to regress in testis weight before summer solstice, although all are spermatogenic until July. By this time, females are incubating the last clutch of eggs of the season and almost all other adults are postbreeding. They revert rapidly to gonads of winter size and status.In most reproductive parameters, those of the American robin of southwestern British Columbia are essentially like those of robins throughout the rest of North America; however, two major differences have emerged in this study. One concerns this robin's seasonally early deviation from hatching time predictions for the American robin elsewhere, based on April noon-time temperature variables, and the other is its rate of egg-to-fledgling success which is higher than that recorded for any other subspecies.