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.
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.
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.
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.
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.
Three hundred and eighty one sooty shearwaters (Puffinus griseus), 2,209 New Zealand white‑faced storm petrels (Pelagodroma marina maoriana) and 14,546 fairy prions (Pachyptila turtur) were banded at Motunau Island, Canterbury, South Island, New Zealand between 1960 and 1999. One sooty shearwater was recovered off the coast of Washington State, USA and 4 others off Motunau Island; the oldest sooty shearwater recovered was found near Taieri airport over 23 years after banding as an adult. Only 1 white-faced storm petrel was recaptured away from Motunau Island and that was found alive on Pitt Island, Chatham Islands. The oldest white-faced storm petrel recovered was found alive on Motunau Island nearly 13 years after banding. Fourteen fairy prions were found on New Zealand’s east coast between Brighton Beach, Christchurch, and Hikutaia near Thames. One fairy prion from Stephens Island and 2 from The Brothers were found at Motunau Island; one was the oldest bird recovered at over 21 years since banding as an adult. Estimates of population sizes based on recapture numbers were 300 for sooty shearwater, 1,300 for white-faced storm petrel and 50,000-60,000 for fairy prion.
Weights and measurements of 120 male and 109 female adult and juvenile Australasian shovelers (Anas rhynchotis) were obtained from fresh specimens shot in May, mostly during 1976-1979, at 2 sites in North Island, New Zealand. Mean weights of adult males (634 g) and juvenile males (616 g) were significantly greater than those of adult (608 g) and juvenile (558 g) females. For both sexes, weight/tarsus length2 ratios of juveniles were significantly lower than adults but there was no difference between sexes within each age class. Measurements of bill length and width, tarsus and mid-toe-and-claw, and wing and tail lengths are presented for each sex and age class. All measured characters of juvenile males were significantly longer than juvenile females and adult males were significantly longer than adult females. Within each sex, only wing and tail lengths of adults were significantly longer than juveniles. These findings are typical of other shoveler species.
The field identification of the orange-fronted parakeet (Cyanoramphus malherbi) has been a problem since the species was first described in 1857. Separating this critically endangered species from its more common, but also declining sympatric relative, the yellow-crowned parakeet (C. auriceps), can be difficult, as both species are cryptic and phenotypically similar. To develop criteria for consistent identification, we assessed >2,700 field observations on the orange-fronted parakeet and >10,000 field observations for the yellow-crowned parakeet, where the phenotypes of each bird was compared to the traits of the genetically defined species and verified type specimens. Observations on 117 nests also allowed observations of young from nestling to independence. We concluded that only 2 field marks can be used to reliably separate the 2 species but a clear view of either the frons or rump patch must be seen. The orange-fronted parakeet has an obvious orange frons and rump patch while these areas on the yellow-crowned parakeet are crimson. No other field traits consistently separated the 2 species. Even then, identification can be unreliable when observing juveniles, when light conditions are poor, or if the bird is high in the canopy. We recommend that unless the observer sees a clear and obvious colour in the frons or rump patch, then that bird must remain as unidentified to species.
Over 100 Hutton’s shearwater (Puffinus huttoni) nestlings were translocated to the Te Rae o Atiu colony on the Kaikoura Peninsula in February and March 2013. Passive integrated transponder (PIT) tags were implanted in all translocated nestlings and their movements were monitored using both visual observations and recording devices at nest-box entrances. Once nest-box entrances were unblocked about 5 days after birds were translocated, 29 nestlings were resighted 81 times outside their home nest-boxes either in the open (14 nestlings) and/or other nest-boxes (29 nestlings). From the PIT tag records, 37 birds were observed visiting at least 49 nest-boxes on 109 occasions. The most mobile bird made 15 visits to 12 other nest-boxes over 9 nights; another bird visited 6 boxes in one night; and 1 box had 3 visitors in a single night. Nestlings moved within the colony in the period between 1 and 16 nights before fledging, with an average of 8 nights with movement before fledging. The PIT tag readers also showed that the use of pins outside nest-box entrances to determine movements can be misleading as pins were moved up to 13 nights before the nest-box occupant emerged, the pins being moved either by visitors to the nest-boxes or by nestlings wandering past the entrance.
The South Island kokako (Callaeas cinerea) was officially declared extinct in 2007, with the most recent report accepted by the Ornithological Society of New Zealand’s Rare Birds Committee, being in 1967. However reports of potential observations of South Island kokako continued to appear. We compiled a total of 241 reports between January 1990 and June 2012. These reports were categorised into 6 categories depending on the details provided by observers. The most highly ranked reports required identification of the wattles which are the most distinguishing feature of South Island kokako. The 13 reports from the highest category were submitted to the Bird Threat Ranking panel in June 2012 and, based on this evidence, the species was then reclassified from “extinct” to “data deficient”. The most compelling 11 reports were then submitted to the Ornithological Society of New Zealand’s Records Appraisal Committee (RAC). One report was accepted as a South Island kokako while 2 were deemed to be of North Island kokako. This paper reviews all available reports of the South Island kokako from 1990, the assessment process and a map of the distribution of reports. Our analysis of these reports suggests that the South Island kokako is extant.
The breeding ecology and reproductive traits of brown booby (Sula leucogaster etesiaca) were studied in Gorgona Natural National Park, Colombia. Adult morphometrics, egg dimensions, chick growth and nesting site characteristics, were examined at 3 locations in the park. As with other subspecies, brown boobies in Gorgona exhibit reversed sexual dimorphism. The female booby reaches about 80 cm in length, its wingspan measures up to 150 cm, and they can weigh up to 1,300 g. The male booby reaches about 75 cm in length, its wingspan measures up to 140 cm, and they can weigh up to 1,000 g. First-laid eggs were heavier and bigger than second- or third-laid eggs. Growth of brown booby chicks fit a natural log equation: body mass (g) = 0.8773 ln * days + 3.3895. A variety of nesting aggregations was found, and their relationship with the other marine birds nesting in the area is discussed.
I conducted observations on the diet of the Floreana mockingbird (Mimus trifasciatus) during its breeding season in February and March 2011. The Floreana mockingbird is a critically endangered species restricted to Gardner and Champion Islets off the coast of Floreana Island, in the Galápagos Islands, Ecuador. During 11 days, 172 feeding bouts of adult and nestling mockingbirds were observed. The majority of feeding bouts of adults (31%; 19 feeding bouts) involved the consumption of nectar and pollen of Opuntia megasperma. Another important food item consisted of Lepidopteran caterpillars (27%; 17 feeding bouts). The majority of food items fed to nestlings consisted of Lepidopteran caterpillars (26%; 29 observations), followed by adult spiders (19%; 21 observations). The reintroduction of the species to its historical range on Floreana Island is currently being planned with an emphasis on the control or eradication of invasive cats and rats. To identify key areas for reintroduction, a study on the year-round diet of the species as well as availability and variability of food items is recommended. Nectar and pollen of Opuntia megasperma was an important dietary item for the species during its breeding season. This slow-growing plant species was widespread on the lowlands of Floreana Island but introduced grazers removed Opuntia from most of its range. In the context of the potential reintroduction of this species to Floreana Island, it is important to establish if this high-energy resource is key for breeding, and consideration should be given to a supplementary food program as it has been successfully implemented for bird species elsewhere.
The monitoring of endemic birds during the control of introduced mammalian predators is a common practice at community-based conservation projects in New Zealand. We describe long-term trends of endemic passerines monitored using the presence-absence technique during the control of stoats (Mustela erminea) and brushtail possums (Trichosurus vulpecula) in the Flora Valley, near Nelson, New Zealand. Data collected over an 8 year period by Friends of Flora, a community-based organisation, suggests that bellbirds (Anthornis melanura) significantly increased, while South Island robin (Petroica australis), tomtit (P. macrocephala) and rifleman (Acanthisitta chloris) populations showed little or no change, and grey warblers (Gerygone igata) significantly decreased. All species showed a greater increase during the first 4 years of the survey compared to the second 4 years, which suggests that meso-predator release of rats may have occurred from ~4 years after the start of the surveys. The presence-absence technique is simpler to conduct than the more commonly used 5-minute bird count method, and thus may be better suited for use by the community sector in similar situations.
We present counts of white blood cells of wild and clinically normal red-crowned parakeets (Cyanoramphus novaezelandiae) from 2 island populations in New Zealand. Total white blood cell counts on slides prepared in the field and counts of relative proportion of basophils, eosinophils, heterophils, lymphocytes and monocytes were determined for 33 individuals caught on Little Barrier Island and 48 individuals caught on Raoul Island. Mean haematological parameters were: total white blood cells 6.85 cells x 109/L, lymphocytes 5.0 x109/L (74.0%), monocytes 3.5 x109/L (5.7%), eosinophils 4.6 x109/L (6.4%), basophils 1.9 x 109/L (3.1%), and heterophils 9.9 x109/L (14.7%). Raoul Island parakeets had significantly higher counts of white blood cells, lymphocytes, and heterophils than Little Barrier Island parakeets, possibly reflecting latitudinal differences. Males showed significantly higher counts of white blood cells and lymphocytes than females. White blood cell counts on slides prepared in the field represent an inexpensive and straightforward technique to determine variation in the levels of each cell type and to assess the physiological state of healthy and diseased individuals. This information is useful for veterinary clinicians, wildlife managers, and conservation biologists who increasingly require methods for health assessment, disease diagnosis, and screening for pathogenic microorganisms on species of conservation concern.
Twenty five bird species were recorded following 2 brief winter visits to the southern Kermadec Islands during 2002 and 2006. Of these, 15 were seabirds and 10 land or shorebirds. Rapid changes in the dominant vegetation cover occurred between 1988 and 2002. Ferns replaced grass and sedge swards over much of the island, and although this succession was rapid, the distribution of woody species (the presumed historical dominant cover) did not change, most likely due to limited seed sources, Pacific rat (Rattus exulans) predation, and competition for space from other species. Possible impacts of these changes on the avifaunal composition of Macauley Island are discussed. Following the presumed eradication of Pacific rats from Macauley Island in 2006, recommendations are made for future vegetation and bird monitoring.
Opportunities to monitor natural island ecosystem recovery following the eradication of introduced predators are rare, and provide a useful comparison for recovery programmes aided by active habitat restoration and species translocations. We present an assessment of the current avifauna on Burgess Island, Mokohinau Group, 2 decades after kiore (Pacific rat; Rattus exulans) removal. The 4 most abundant land bird species we recorded are red-crowned parakeet (Cyanorhamphus novaezelandiae), bellbird (Anthornis melanura), tui (Prosthemadera novaeseelandiae) and silvereye (Zosterops lateralis), all New Zealand native taxa. Our records confirm that 46 species now utilize the island’s habitats, compared with 24 species reported from the literature during the last decades of rat infestation. We also confirm breeding of 9 seabird species by 2011, only 4 of which maintained breeding populations on Burgess Island prior to rat eradication. More than 20 years after predator removal, Burgess Island hosts a rich avifauna, and provides a valuable example of natural recovery following predator eradication without any further active restoration measures.