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Emu - Austral Ornithology
Volume 115, Issue 3, 2015 Summaries
The size and composition of social groups in the wild zebra finch
Luke S. C. McCowan, Mylene M. Mariette and Simon C. Griffith
Emu – Austral Ornithology 115(3), 191–198
http://www.publish.csiro.au/paper/MU14059.htm
The gregarious zebra finch is widely used by laboratory researchers as a model species to study a
range of questions in behavioural science. We observed the group size and composition of wild zebra
finches during two brief non-breeding periods near semi-permanent water sources (artificial dams) in
the arid zone of Australia, by conducting both stationary and moving observations. We found that
individuals most commonly foraged, watered and travelled around the colonies in mixed-sex groups of
two, which most likely reflected sexual pairs, or in larger usually mixed-sex groups of 3–10 individuals.
These observations indicate that individuals spend a lot of time with their partners even when they are
not breeding. Moreover, they indicate that the best way for researchers to emulate the social
environment of wild zebra finches in captivity is to keep individuals in pairs or small mixed-sex social
groups.
The effects of land-use change on the endemic avifauna of Makira, Solomon Islands: endemics
avoid monoculture
Tammy E. Davies, Rohan H. Clarke, John G. Ewen, Ioan R. A. Fazey, Nathalie Pettorelli and Will
Cresswell
Emu – Austral Ornithology 115(3), 199–213
http://www.publish.csiro.au/paper/MU14108.htm
Land-use change, such as deforestation, is a major threat to biodiversity. This problem is particularly
acute on tropical islands, which are home to a high number of endemic species and important sites for
conservation. We assessed the impacts of land-use change on the tropical island of Makira, Solomon
Islands, by assessing bird numbers and abundance across a gradient of land-use intensity from intact
forests (low intensity) to monoculture cocoa plantations (high intensity). We found that the number of
endemic species declined with increasing intensity of land use, with the fewest endemics found in
monoculture cocoa. We also found significant differences in the distribution of bird feeding and habitat
characteristics, suggesting changes in ecological functioning may be occurring. Protecting the
remaining intact forest areas will therefore be important for the conservation of Makira endemic birds.
This study contributes empirical evidence for understanding the implications of changes in land-use on
biodiversity, which is needed to help guide conservation actions.
Breeding success, mate-fidelity and nest-site fidelity of Red-tailed Tropicbirds (Phaethon
rubricauda) on Christmas Island, Indian Ocean
Julia Sommerfeld, Tony Stokes and G. Barry Baker
Emu – Austral Ornithology 115(3), 214–222
http://www.publish.csiro.au/paper/MU14016.htm
Disruption of pair-bonds and switching nest-site are associated with breeding failure in many seabirds.
Both strategies can prevent repetition of poor performance with a low-quality mate or at a poor-quality
nesting site. In the Red-tailed Tropicbird (Phaethon rubricauda), the relationship between mate-fidelity,
nest-site fidelity and reproductive performance is poorly understood. We therefore examined these
relationships in Red-tailed Tropicbirds, using data collected on Christmas Island in the Indian Ocean
from 1984 to 1986, corresponding to three successive breeding seasons. Birds showed strong
between-season mate-fidelity, despite previous breeding failure, and subsequent breeding success in
birds faithful to their mate was significantly higher than in pairs that bred together for the first time,
indicating that mate-fidelity may outweigh the costs of disruption of pair-bonds. Although switching of
nest-site was more likely to occur after previous breeding failure, it did not increase subsequent
breeding success, indicating that nest-site switching may not be advantageous in Red-tailed
Tropicbirds on Christmas Island. Although effects of age, dispersal rates to inaccessible parts of the
island and adult survival were not examined in this study, our results provide a valuable basis for the
evaluation of population dynamics of Red-tailed Tropicbirds on Christmas Island.
The subspecies of Antarctic Terns (Sterna vittata) wintering on the South African coast:
evidence from morphology, genetics and stable isotopes
Maëlle Connan, Peter R. Teske, Anthony J. Tree, Philip A. Whittington and Christopher D. McQuaid
Emu – Austral Ornithology 115(3), 223–236
http://www.publish.csiro.au/paper/MU14089.htm
Antarctic Terns (Sterna vittata) breed on the Antarctic Peninsula and subantarctic islands. Of seven
subspecies recognised globally, three have been recorded wintering in southern Africa. Given the
disparity in population numbers among breeding colonies, a better understanding of meta-population
dynamics within the species, and how these relate to the conservation status of the different
subspecies, is necessary. Due to the remoteness of their breeding sites and their sensitivity to
disturbance, we sampled birds originating from various breeding colonies when wintering in South
Africa. We assessed variations among subspecies from morphometric, genetic and isotopic analyses.
Results supported the existence of S. v. vittata and S. v. tristanensis. However, the existence of S. v.
sanctipauli could not be confirmed, and data indicated that morphological groupings may rather reflect
a north–south cline across the Indian Ocean. Adequate conservation strategies will require rigorous
reassessment of the currently accepted subspecies, including DNA analyses of samples from the
breeding grounds, particularly on Amsterdam and St Paul Islands.
Combining a geographic information system, known dietary, foraging and habitat preferences,
and stable isotope analysis to infer the diet of Magellanic Penguins in their austral distribution
Javier Ciancio, Florencia Botto and Esteban Frere
Emu – Austral Ornithology 115(3), 237–246
http://www.publish.csiro.au/paper/MU14032.htm
Penguins are high energy demanding predators that consume large amounts of fish and squid, and
could also be threatened by human activities such as fisheries and pollution. We combined all the
available information to try to infer the diet of a third of the Magellanic Penguin world population, which
inhabits a poorly studied region: the Southern Patagonian Shelf Ecosystem. By means of stable
isotopes in penguin blood, fishery distribution data of prey and stomach content analysis, we showed
that Magellanic Penguins forage on few prey species not targeted by commercial fisheries in this
ecosystem, contrary to other regions where many threats have been identified.
How does nest-box temperature affect nestling growth rate and breeding success in a parrot?
Eliza R. Larson, Justin R. Eastwood, Katherine L. Buchanan, Andrew T. D. Bennett and Mathew L.
Berg
Emu – Austral Ornithology 115(3), 247–255
http://www.publish.csiro.au/paper/MU14081.htm
Climate change is predicted to affect many species by reducing range, habitat suitability and breeding
success. Cavity-nesting species, already threatened by deforestation and declining natural hollows,
may be particularly at risk because they are limited in nest-site location, and climatic alterations may
further reduce usability of natural cavities. We recorded internal nest-box temperatures and modelled
the relationships of four temperature parameters (relating to mean temperature, variability in
temperature, low temperature extremes and high temperature extremes) with breeding success and
nestling growth in an Australian cavity-nesting parrot, the Crimson Rosella (Platycercus elegans). We
found that less extreme low temperatures resulted in heavier nestlings; however, higher mean
temperatures tended to result in lighter nestlings. Greater temperature variability tended to reduce
fledging success; however, no temperature variables had a clear effect on clutch size or hatching
success. Our findings indicate that there may be a complex relationship between nestling growth and
temperature, and although less extreme cold temperatures may benefit nestlings, continued increases
in mean temperature and variability may have negative consequences.
Barn Swallows keep expanding their breeding range in South America
Juan Manuel Grande, Miguel Santillán, Paula M. Orozco, María Soledad Liébana, Marcos Matías
Reyes, Maximiliano Adrián Galmes and Joaquín Ceregheti
Emu – Austral Ornithology 115(3), 256–260
http://www.publish.csiro.au/paper/MU14097.htm
Barn Swallows (Hirundo rustica) breeding in North America traditionally wintered in South America. In
the 1980s a small breeding population was found in coastal Argentina and since then the breeding
range of Barn Swallows in the country has expanded. Our aims here were to examine the northwestern limits of the breeding range of Barn Swallows in Argentina, and to analyse the factors that
may determine selection of nesting site by the species. We surveyed and characterised culverts and
bridges below roads, in an area of 15 000 km2 in northern La Pampa Province, central Argentina. We
found 51 nests in 39 culverts and bridges through most of the surveyed area. We also found 16 nests
outside that area, in central Buenos Aires and La Pampa Provinces. Occupied culverts were higher
and were more often associated with wetlands than unoccupied culverts. Most nests were in
agricultural landscapes, with just a few in native Caldén (Prosopis caldenia) forests. Our results
confirm that the breeding range of the species in South America has expanded by about a third in
relation to previous studies, but there is still a large area of suitable habitat for the species, suggesting
that further expansion of the range of the species can be expected.
Exploring food preferences and the limits of feeding flexibility of seed-eating desert birds
Sergio R. Camín, Víctor R. Cueto, Javier Lopez de Casenave and Luis Marone
Emu – Austral Ornithology 115(3), 261–269
http://www.publish.csiro.au/paper/MU14090.htm
Human pressure on ecosystems is one of the main causes of biodiversity loss. Livestock grazing in
arid lands triggers environmental changes that usually begin with a reduction of herbaceous plants
and their seeds. Under such conditions, seed-eating animals (some birds, ants and mammals) may
suffer food deprivation, although ecologically flexible species could survive via changes in foraging
behaviour, and by feeding more on alternative food items. We asked whether some common birds of
the Monte desert, Argentina, are able to consume alternative seed items when preferred items
become scarce. Zonotrichia capensis displayed very flexible behaviour, consuming grass and forb
seeds in all sizes, and was able to eat seeds from grasses that usually invade degraded areas. In
contrast, Saltatricula multicolor was a stereotypical consumer that depended greatly on large grass
seeds. Diuca diuca showed an intermediate behaviour. Different, species-specific population
responses to grazing may be predicted for these birds.
Responses of birds to planting of Lotus tenuis pasture in the Flooding Pampas, Argentina
Manuel Agra, David Bilenca and Mariano Codesido
Emu – Austral Ornithology 115(3), 270–276
http://www.publish.csiro.au/paper/MU14075.htm
The current need to increase forage production in order to meet the increasing demand for meat
products is clear. How does this affect bird life? Is it possible to reconcile production with conservation
goals? We chose to investigate this relationship in the Flooding Pampas, the most important livestock
region of Argentina, by evaluating the response of grassland bird assemblages to planting of Lotus
tenuis (Lotus) pasture compared to semi-natural grasslands. Avian species richness and abundance
were both greater in semi-natural grassland than in Lotus pasture. An indicator-species analysis
showed that five grassland birds were closely linked to semi-natural grassland vegetation, with two of
those species – Hudson’s Canastero (Asthenes hudsoni) and Bay-capped Wren-Spinetail
(Spartonoica maluroides) – of conservation concern. Grassland management methods such as
intercropping and rotational grazing could help reconcile the effects of livestock production and the
conservation grassland bird conservation in the Flooding Pampas.
What the direction of matings can tell us of hybridisation mechanisms in ducks
Patrick-Jean Guay, Lucinda Monie, Randall W. Robinson and Wouter F. D. van Dongen
Emu – Austral Ornithology 115(3), 277–280
http://www.publish.csiro.au/paper/MU14064.htm
Hybridisation occurs when two different species breed and produce young. Animals may breed with
individuals of other species for a diversity of reasons. For example, mistakes may occur in species
recognition or animals may actually prefer to mate with other species. Discriminating between these
explanations is often problematic due to the difficulties of observing matings in the wild. The direction
in which hybridisation occurs may, however, provide some insights into why animals breed with other
species. For example, matings may occur exclusively in one direction when females of both species
prefer to mate with males of only one of the species. In contrast, matings are more likely in both
directions when other mechanisms operate, such as imprinting on other species due to brood mixing
(i.e. the mixing of eggs of different species within one nest). We characterised the direction of matings
that produced Grey Teal and Pacific Black Duck hybrids. Using genetics, we show that hybridisation
occurs bidirectionally. We suggest that errors in species recognition are improbable and that active
mating preferences for individuals of other species, possibly due to brood mixing, may more likely
promote hybridisation between Grey Teals and Pacific Black Ducks.
D. L. Serventy Medal 2015: Citation – Stephen J. S. Debus
James Fitzsimons, Alan Lill and Hugh Ford
http://www.publish.csiro.au/paper/MUv115n3_DLS.htm
Obituary: William Thomas Cooper, 6 April 1934–10 May 2015
Penny Olsen
http://www.publish.csiro.au/paper/MUv115n3_OB.htm
Book review
WHERE SONG BEGAN: AUSTRALIA’S BIRDS AND HOW THEY CHANGED THE WORLD
By Tim Low
http://www.publish.csiro.au/paper/MUv115n3_BR.htm
Corrigendum to: The Common Myna (Sturnus tristis) in urban, rural and semi-rural areas in
Greater Sydney and its surrounds
Julie M. Old, Ricky-John Spencer and Jack Wolfenden
http://www.publish.csiro.au/paper/MU13029_CO.htm
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