Habitat use throughout migration : linking individual consistency, prior breeding success and future breeding potential

1. Habitat use can influence individual performance in a wide range of animals, either immediately or through carry-over effects in subsequent seasons. Given that many animal species also show consistent individual differences in reproductive success, it seems plausible that individuals may have consistent patterns of habitat use representing individual specializations, with concomitant fitness consequences.

2. Stable-carbon isotope ratios from a range of tissues were used to discern individual consistency in habitat use along a terrestrial–aquatic gradient in a long-distance migrant, the Bewick’s swan (Cygnus columbianus bewickii). These individual specialisations represented <15% of the isotopic breadth of the population for the majority of individuals and were seen to persist throughout autumn migration and overwintering until aquatic habitats were no longer available.

3. Individual foraging specialisations were then used to demonstrate two consecutive carry-over effects associated with macroscale habitat segregation: consequences of breeding season processes for autumn habitat use; and consequences of autumn habitat use for future reproductive success. Adults that were successful breeders in the year of capture used terrestrial habitats significantly more than adults that were not successful, revealing a substantial cost of reproduction and extended parental care. Use of aquatic habitats during autumn was, however, associated with increased body condition prior to spring migration; and increased subsequent breeding success in adults that had been unsuccessful the year before. Yet adults that were successful breeders in the year of capture remained the most likely to be successful the following year, despite their use of terrestrial habitats.

4. Our results uniquely demonstrate not only individual foraging specializations throughout the migration period, but also that processes during breeding and autumn migration, mediated by individual consistency, may play a fundamental role in the population dynamics of long-distance migrants. These findings, therefore, highlight the importance of long-term consistency to our understanding of habitat function, interindividual differences in fitness, population dynamics and the evolution of migratory strategies.

Kin selection, not group augmentation, predicts helping in an obligate cooperatively breeding bird

Kin selection theory has been the central model for understanding the evolution of cooperative breeding, where non-breeders help bear the cost of rearing young. Recently, the dominance of this idea has been questioned; particularly in obligate cooperative breeders where breeding without help is uncommon and seldom successful. In such systems, the direct benefits gained through augmenting current group size have been hypothesized to provide a tractable alternative (or addition) to kin selection. However, clear empirical tests of the opposing predictions are lacking. Here, we provide convincing evidence to suggest that kin selection and not group augmentation accounts for decisions of whether, where and how often to help in an obligate cooperative breeder, the chestnut-crowned babbler (Pomatostomus ruficeps). We found no evidence that group members base helping decisions on the size of breeding units available in their social group, despite both correlational and experimental data showing substantial variation in the degree to which helpers affect productivity in units of different size. By contrast, 98 per cent of group members with kin present helped, 100 per cent directed their care towards the most related brood in the social group, and those rearing half/full-sibs helped approximately three times harder than those rearing less/non-related broods. We conclude that kin selection plays a central role in the maintenance of cooperative breeding in this species, despite the apparent importance of living in large groups.

Do temporary beach closures assist in the conservation of breeding shorebirds on recreational beaches?

Recreational use of beaches may threaten some beach-nesting shorebirds in southern Australia. Temporary Beach Closures, comprized of a 50 x 25 m exclusion zone around a shorebird nest, represent a promising technique for altering human behaviour by reducing both disturbance to birds and inadvertent crushing of eggs by beach visitors. We assessed whether three commonly employed configurations of Temporary Beach Closures (sign, fence, and warden) were effective at: (1) achieving compliance among beach visitors, and (2) reducing egg-crushing rates. Overall, 93.7% of beach visitors complied with all Temporary Beach Closures, resulting in a reduction in egg-crushing rates within, as opposed to adjacent to, Temporary Beach Closures. Levels of compliance were high in all Temporary Beach Closure configurations (88.0-99.4%), and similar levels of compliance were achieved within the three configurations. Human compliance was highest for females and when the density of beach-users was higher, while individuals aged <20 and >61 years were less likely to comply with Temporary Beach Closures. Despite an increased probability of compliance on high density beaches, this did not translate into a reduction in egg crushing rates on such beaches, because the overall number of noncompliant individuals remained higher. We conclude any Temporary Beach Closure configuration is meritorious, and that their use on high and low-use recreational beaches will benefit breeding shorebirds by reducing the rate of egg-crushing. Targeting demographics that display lower levels of compliance, such as men, young people (i.e. <21), and older people (i.e. >60), may further improve the effectiveness of Temporary Beach Closures in enhancing the conservation of shorebirds.

Establishment and development of a seabird colony : long-term trends in phenology, breeding success, recruitment, breeding density and demography

Few studies document long-term colony-level metrics from colony establishment to maturity (equilibrium) and few test predictions of general models of colony development. We describe long-term trends in a colony of Australasian Gannets (Morus serrator) which has been monitored from an early stage in its development. The colony at Pope’s Eye, within Port Phillip Bay, Victoria, Australia was established in 1984 on an artificial structure and the first nest count (25 nests) was conducted in the same year. The colony was then studied for 15 of 19 years between 1988 and 2006–2007. During the study, 2,516 eggs were recorded, resulting in 1,694 chicks hatching (67 % of eggs), of which 1,310 (77 % of those hatched) fledged. At least 184 (14 %) of fledged offspring returned to Pope’s Eye as breeding adults. Since establishment, the number and density of nests increased (number of nests increased 8.8 % annually), with density increasing at varying rates in different areas of the colony. Early recruitment involved birds from a nearby colony, but within 5 years post establishment the first natal recruits were breeding at Pope’s Eye and thereafter natal recruitment was the main source of new breeding adults (totalling 81.4 % of all recruits). Age of recruitment varied throughout the study, though not systematically, and there was no difference between the sexes. The pattern of rapid initial growth is typical of patterns reported for other seabird colonies. However, as the colony (and birds within it) aged, there was no increase in breeding success and egg laying did not become earlier, as was expected from general models of colony development.

Climate as a driver of population variability in breeding Gentoo Penguins (Pygoscelis papua) at the Falkland Islands

Detecting and predicting how populations respond to environmental variability are eminent challenges in conservation research and management. This is particularly true for wildlife populations at high latitudes, many of which demonstrate changes in popula

An increase in minimum metabolic rate and not activity explains field metabolic rate changes in a breeding seabird

The field metabolic rate (FMR) of a free-ranging animal can be considered as the sum of its maintenance costs (minimum metabolic rate, MMR) and additional costs associated with thermoregulation, digestion, production and activity. However, the relationships between FMR and BMR and how they relate to behaviour and extrinsic influences is not clear. In seabirds, FMR has been shown to increase during the breeding season. This is presumed to be the result of an increase in foraging activity, stimulated by increased food demands from growing chicks, but few studies have investigated in detail the factors that underlie these increases. We studied free-ranging Australasian gannets (Morus serrator) throughout their 5 month breeding season, and evaluated FMR, MMR and activity-related metabolic costs on a daily basis using the heart rate method. In addition, we simultaneously recorded behaviour (flying and diving) in the same individuals. FMR increased steadily throughout the breeding season, increasing by 11% from the incubation period to the long chick-brooding period. However, this was not accompanied by either an increase in flying or diving behaviour, or an increase in the energetic costs of activity. Instead, the changes in FMR could be explained exclusively by a progressive increase in MMR. Seasonal changes in MMR could be due to a change in body composition or a decrease in body condition associated with changing the allocation of resources between provisioning adults and growing chicks. Our study highlights the importance of measuring physiological parameters continuously in free-ranging animals in order to understand fully the mechanisms underpinning seasonal changes in physiology and behaviour.

Occurrences of cooperative breeding in the masked lapwing vanellus miles

The Masked Lapwing Vanellus miles is a common ground-nesting shorebird inhabiting grasslands, paddocks, rivers, lakes, swamps and, tidal mud flats. It is particularly common in the urban areas of Phillip Island, Victoria (Dann 1981, Marchant and Higgins 1993). The Masked Lapwing usually lays between one and four eggs (the mean number of eggs per clutch of this study was 3.6 ± 1 SD) that hatch after 31 days. Both sexes incubate eggs, brood young and defend the eggs and young. Masked Lapwings produce precocial and nidifugous chicks that remain with the adults on defended territories until fledging (Marchant and Higgins 1993, Thomas 1969). The chicks are able to feed themselves within hours of hatching and rely on their parents only for protection (alarm signals) and warmth (brooding) (Marchant and Higgins 1993). Here we report three instances of likely co-operative breeding of Vanellus miles on Phillip Island between 18 July and 13 September 2012.

Population trends of Gentoo Penguins Pygoscelis Papua breeding at the Falkland Islands

The fourth archipelago-wide census of Gentoo Penguins Pygoscelis papua breeding at the Falkland Islands was conducted from 24 October to 8 December 2010. The number of Gentoo Penguins breeding in 2010 was estimated to be 132 321 ± 2 015, the highest number of breeding pairs recorded for this species at the Falkland Islands since the first survey in 1933. The global population of Gentoo Penguins is conservatively estimated to be about 384 000 breeding pairs, of which the Falkland Islands accounts for 34%, probably the largest component of the global population. Annually monitored study colonies accounted for 20% of the total number of Gentoo Penguin breeding pairs at the Falkland Islands in 2010 and proved to be a reliable proxy for archipelago-wide changes in the number of breeding pairs. Recent trends at annually monitored study colonies, combined with archipelago-wide trends, indicate that the number of Gentoo Penguins breeding at the Falkland Islands has increased between 2005 to 2010. However, annual monitoring data also revealed large inter-annual variability in the number of breeding pairs, which makes assessing systematic population changes challenging.

Home-range, diet and breeding of a Powerful Owl Ninox strenua in East Gippsland, Victoria

Between 2004 and 2008 the diet and breeding success of a pair of Powerful Owls Ninox strenua were studied near Lakes Entrance, Victoria. In early November 2006 the adult female Powerful Owl was captured and radio-tracked for a period of 7.5 months. During this time the Owl's location was recorded on 111 occasions, including 65 nocturnal locations over 29 nights. Her home-range was calculated as 1589 ha using the Minimum Convex Polygon (MCP) method, or 871 ha based on the 95% Adaptive Kernel method. The area of forested habitat within the MCP home-range was 896 ha (the remainder representing cleared land). Her activity was centred primarily on the nesting gully where two dependent juveniles roosted, but several long-distance foraging expeditions (including roosting) that occurred more than 2.5 km from the juveniles were recorded. Arboreal mammals and birds dominated the Owls' diet. Low prey availability is suggested as being responsible for the single successful breeding event recorded in four nesting seasons.

Sickness ruins the complexion, breeding disappears without gold: culture and the i nterpretation of illness among the Minangkabau of West Sumatra, Indonesia

The interpretation of illness and its meaning to individuals and groups is largely a product of culture and is based on shared experience, historical significance, and the social function of individuals in the community. West Sumatra, like many parts of Indonesia, has experienced rapid development and modernization since the nation achieved independence in 1945 and is currently 12 years into Regional Autonomy, a dramatic shift in national administration from a highly centralized system to one which devolved authority to the level of district or municipal government. These changes have brought Indonesians into contact with an increasingly globalized culture and have put pressure on traditional institutions and practices. This is especially significant in the area of health, where considerable tension exists between the allopathic conceptualization of health (as espoused by health care professionals in the formal sector) and traditional interpretations of health that derive from a traditional cultural and linguistic frame of reference. This paper, based on fieldwork in the Indonesian region of Tanah Datar, West Sumatra, describes the impact of cultural and linguistic factors on the interpretation of illness among rural residents and elucidates the growing impact of multiple systems of meaning in local understanding of health.