Abstract. We compared the predation rate on natural nests of the Eastern Yellow Robin, Eopsaltria australis, with the predation rates on four types of artificial nests in a woodland remnant in southern Victoria. The aims of this study were: to compare the overall rates of predation on artificial and natural nests; to determine whether artificial nests accurately reflect the effects of nest-site characteristics on the predation rate of natural nests; and to examine the effects of using different nest types and egg types for artificial nests. The predation rates on artificial nests were significantly greater than those on natural nests. The predation rate was significantly greater on artificially constructed nests than on real, disused Eastern Yellow Robin nests, but there was no difference in the predation rates on artificial nests containing plasticine or Canary, Serinus canarius, eggs. There were no effects of nest-site characteristics on the predation rates on either artificial or natural nests. These results showed that the method of construction of artificial nests can affect the rate of nest predation, and suggest that artificial nests should be made as realistic as possible in order to gain more accurate information on the predation rates on the natural nests they are meant to represent.

An important consequence of habitat fragmentation for wildlife communities is the effect of an increase in the ratio of habitat edge to interior. This study compares the bird communities at forest/farmland edges and in forest interior at Bunyip State Park, Victoria. Overall, there was a significantly higher number of bird species and individuals in forest edge than in forest interior sites. The greater diversity of species at edge sites appeared to be due to an increase in forest-edge specialists, as opposed to an influx of open-country species. Four bird species: the white-throated treecreeper (Cormobates leucophaeus), the superb fairy-wren (Malurus cyaneus), the grey shrike-thrush (Colluricincla harmonica) and the grey fantail (Rhipidura fuliginosa) were significantly more abundant in edge sites. There were no species that were significantly more abundant in interior sites. Differences between the bird communities in edge and interior sites were attributed to increased foraging opportunities in the open country adjacent to forest edges.

Predation rates of nests at human-induced habitat edges may be greater than in forest interior due to differences in predator assemblages and predator activity. I compared the predation rates on 192 artificial nests containing plasticine eggs placed in forest edge and interior sites at Bunyip State Park, Victoria. The nest-predation rates at the forest edge sites were significantly greater (mean = 52–58%) than that at the forest interior sites (mean = 30–39%). The relative rates of predation by birds compared with mammals were significantly greater at forest edge sites (mean = 78–94%) than at forest interior sites (mean = 36–67%). Higher rates of nest predation at forest edges appeared to be due to greater densities of avian predators such as the grey shrike-thrush (Colluricincla harmonica), and/or lower abundances of small mammals. However, biases towards certain predator types may mask real, or create false, patterns in predation rates of artificial nests. A better understanding of how predators respond to artificial nests compared with natural nests is required. Until then, results of predation studies that use artificial nests should be interpreted with caution.

The Nightingale Reed-Warbler (Acrocephalus hiwae), a critically endangered songbird, is the last remaining of four reed-warbler species that once inhabited the Mariana Islands. The most recent population estimate for the species is 2915-3742 individuals distributed over the islands of Saipan (n = 2742, 95% CI = 1686-3956) and Alamagan (n = 946, 95% CI = 173-1000), which represents a significant decline for the species on Saipan. Though data on life history parameters such as survival rates are not widely available, other parameters such as clutch size and nest success have been studied. Given the extirpation of three of the four reed-warbler species from the Mariana Islands, the recent significant decline of the larger Saipan population, and the increasing threats faced by the species, it is critical to determine what additional life history information is needed to aid management decisions. Using Vortex, we developed stochastic population models to represent current reed-warbler population dynamics and used sensitivity analysis to identify the life history parameters to which the model was most sensitive. Baseline models without inbreeding indicated declines of the Nightingale Reed-Warbler populations on Saipan and Alamagan, as well as of the overall population. The inclusion of inbreeding further increases the modeled rate of population decline. Parameters such as initial population size, carrying capacity, and male survival have relatively little influence on reed-warbler population models, while female and juvenile survival and, to a lesser degree, fecundity measures, exhibit strong influences on the species' population dynamics. We recommend effort be placed on collecting updated survival data for all life stages, but particularly for females and juveniles. Given model predictions of vulnerability to extinction, we recommend management actions that may increase survival rates of juveniles and females. Facteurs démographiques clés pour le rétablissement de la Rousserolle de Saipan (Acrocephalus hiwae), en voie de disparition critique, au moyen d'analyses de viabilité des populationsRÉSUMÉ. La Rousserolle de Saipan (Acrocephalus hiwae), un passereau en voie de disparition critique, est la dernière des quatre espèces de rousseroles qui se reproduisaient autrefois sur les Mariannes. L'estimation la plus récente de la population de cette rousserolle est de 2 915-3 742 individus répartis sur les îles de Saipan (n = 2 742, IC 95 % = 1 686-3 956) et Alamagan (n = 946, IC 95 % = 173-1 000), ce qui représente une baisse importante de l'espèce sur Saipan. Bien que certaines composantes biodémographiques comme le taux de survie ne soient pas disponibles à grande échelle, d'autres paramètres tels que la taille de la ponte et le succès de nidification ont été bien étudiés. Étant donné la disparition de trois des quatre espèces de rousseroles des Mariannes, du récent déclin prononcé de la plus importante population sur Saipan et des menaces grandissantes auxquelles fait face l'espèce, il est primordial de déterminer quels ...

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