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Analysis of the impacts of a water channel diversion wall on waterbirds inhabiting the western end of Lake Rotoiti, Bay of Plenty, New Zealand

Notornis, 62 (4), 184-191

D. Smith; C. Bycroft; R. McClellan; R. Gillies; W. Shaw (2015)

Article Type: Paper

Cyanobacterial blooms in Lake Rotoiti have been linked to nutrient flows from Lake Rotorua via the Ohau Channel. To mitigate this, a diversion wall was constructed in 2008 that was designed to redirect water entering Lake Rotoiti from Lake Rotorua into the Kaituna River. One concern was whether the presence of the diversion wall might have adverse impacts on the abundance of birds using the lake. Monthly bird counts were undertaken at 8 sites in Lake Rotoiti, over 8 years, and which spanned the period before, during and after construction of the wall. Generalised linear mixed effect models and AIC were used to investigate any effects of the wall on 6 bird species. There was no apparent impact of the wall on 5 of the species. The sixth species, little black shag (Phalacrocorax melanoleucos), was more abundant in sites surrounding the wall post-construction, and appeared to be using the wall for roosting and to hunt for smelt.

Distribution, population status and trends of grey-faced petrel (Pterodroma macroptera gouldi) in the northern North Island, New Zealand

Notornis, 62 (3), 143-161

B.S. Greene; G.A. Taylor; R. Earl (2015)

Article Type: Paper

The distribution, status and trends of grey-faced petrel (Pterodroma macroptera gouldi) populations are summarised from historical records from as early as the 1800’s, but predominantly over a 40 year period from the 1970’s and 1980’s to the present day. We tallied the most recent of 104 island population estimates to give a total range of 72,398-286,268 burrows over a minimum area of 37,967 ha. On predator-free islands (n = 9) during winter, the mean burrow occupancy rate was 60% (± 18 % SD). Fewer than 1000 burrows were detected from 20 mainland sites over an unspecified area. Implications for the conservation of this species are discussed.

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.
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