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Foraging behaviour and habitat partitioning in sympatric invasive birds in French Polynesia

Notornis, 61 (1), 35-42

J.H. Bates; E.N. Spotswood; J.C. Russell (2014)

Article Type: Paper

Interactions among invasive bird species have received relatively little attention despite the potential important consequences for community dynamics and invasion spread. Where species occupy similar environments the outcome may be particularly unpredictable. In this study we examined the foraging behaviours of 2 sympatric invasive birds in Mo’orea, the common myna (Acridotheres tristis) and the red-vented bulbul (Pycnonotus cafer), to determine if they exhibit behavioural or habitat partitioning. We investigated the ratio of foraging to vigilance behaviour of both species at novel food stations, as well as the effects of foraging group size and species composition on their behaviour. While the myna and bulbul exhibit similar behaviour, sites where they occur were partitioned within habitats. Novel food stations however, encouraged foraging at the cost of vigilance behaviours. Behaviours were not influenced by conspecific group size, and intraspecific interactions were more frequent, and of a greater intensity than interspecific interactions. These results suggest that the 2 species minimise competitive interactions by occupying different sites within the same habitat, and prioritise food acquisition in a new environment. Sympatric introduced species may avoid competitive exclusion if habitat usage limits the frequency of interactions.

At-sea observations of Heinroth’s shearwater (Puffinus heinrothi)

Notornis, 61 (2), 97-102

P. Harrison (2014)

Article Type: Paper

This paper reports recent at-sea sightings of the little-known Heinroth’s shearwater (Puffinus heinrothi) within the Solomon Islands. Feeding habits are described and compared to those of black noddy (Anous minutus). Observations suggest that Heinroth’s shearwater occurs in dark, intermediate and pale forms, and may be better considered as a polymorphic species.

Assessing minimum population size of Kermadec parakeets (Cyanoramphus novaezelandiae cyanurus) on Macauley Island, Kermadec Islands

Notornis, 61 (3), 154-161

T.C. Greene; I.M. Westbrooke; D. Brown; P.J. Dilks; J.W. Barkla; R. Griffiths (2014)

Article Type: Paper

The minimum population size of Kermadec parakeets (Cyanoramphus novaezelandiae cyanurus) is reported for Macauley Island in the southern Kermadec Islands group. To minimise population impacts of any accidental parakeet deaths the confirmed presence of a minimum population of 3,000 parakeets was required prior to the attempted eradication of Pacific rats (Rattus exulans) from Macauley Island. Eight pre-defined vegetation strata were identified and 4 count methods ranging from simple counts to distance sampling were assigned to each strata depending on sampling conditions. As the resultant point estimate of 3,484 parakeets during the 29 June to 1 July 2006 survey period was greater than the minimum threshold the rat eradication was able to proceed. The potential impacts of changes in the vegetation on the population dynamics of Kermadec parakeets and recommendations for future monitoring of this species on Macauley Island are discussed.

Calling and display by peacocks (Pavo cristatus) at Mansion House Historic Reserve, Kawau Island, New Zealand

Notornis, 61 (1), 27-34

A.J. Beauchamp (2014)

Article Type: Paper

Information was collected on the calling and display behaviour of 3 peacocks in the absence of peahens at Mansion House Historic Reserve, Kawau Island. The peacocks used an exploded lek display structure from late August to late December. Peacocks predominantly used the eow and occasionally the ka notes during tail displays but were silent during many displays. The overall composition of call notes given during the breeding period differed from than those used in a large dense peafowl breeding population in Japan.

Survival and sex ratio in a mainland population of bellbirds (Anthornis melanura)

Notornis, 61 (2), 91-96

P.M. Sagar; R.P. Scofield (2014)

Article Type: Paper

Both apparent annual survival and population composition were estimated, by age and sex, for bellbirds (Anthornis melanura) from a banding study undertaken on a mainland lowland farm at Pleasant Valley, near Geraldine, New Zealand, during the period 1977-97. The model with the fewest parameters showed that apparent survival varied little between sex and years. Although based on only a few recaptures of subadults, apparent survival of adults (0.694 ± 0.042) was slightly greater than that of sub-adults (0.662 ± 0.128). Annual recapture probabilities of adults (0.104 ± 0.024) were also greater than those of sub-adults (0.042 ± 0.029). A comparison of survival and sex ratios between this population of bellbirds and that on the predator-free Poor Knights Islands showed that demographic parameters vary within this species. The mainland population exhibited a lower overall adult survival rate and more even sex ratio than did the island population. Such demographic variation within a species indicate habitat-specific population parameters.
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