The risk of disorientation by artificial lights and subsequent ‘fallout’ has become a widely recognised issue for nocturnal procellariiform species. Using data from community-based rescue campaigns and systematic research, we assessed the characteristics of fallout events observed in fledglings of the threatened New Zealand endemic Hutton’s shearwater (Puffinus huttoni) or Kaikōura tītī. Despite strong annual variation in observed fallout numbers, the proportion of annually produced fledglings collected as ‘fallout birds’ remained below 1% each year. Among those, more than 80% survived due to community rescue efforts. Fallout was found to increase significantly during new moon, while weather effects remained inconclusive. Most fallout occurred within brightly lit areas of Kaikōura township, particularly along its coastal roads. High light source densities and high wattage lights appeared to be influential in some areas but could only partly explain the spatial distribution of fallout at this small scale.
A total of 49 breeding colonies of 3 petrel species was found on 44 of 56 islands surveyed in Dusky Sound, Fiordland National Park, New Zealand, in November 2016. Sooty shearwater (Puffinus griseus) was the most widespread and abundant species, with an estimated 21,400 burrows on 35 islands. Mottled petrels (Pterodroma inexpectata) were breeding on 12 islands (5500 burrows estimated), and broad-billed prions (Pachyptila vittata) on 2 islands (560 burrows estimated). Sooty shearwaters were found breeding among mottled petrels on 4 islands, and among broad-billed prions on 1 island. This is a 5-fold increase in the number of petrel colonies in Dusky Sound identified in published accounts, and the first estimate of the number of burrows on each island. Long-term survival of most or all of these colonies is dependent on ongoing control of stoats (Mustela erminea) in Dusky Sound. However, we suggest that islands too small to support a resident stoat population provided partial refugia for petrels, even if the islands are within stoat swimming range, allowing petrels to persist for multiple generations. In contrast, petrels were apparently rapidly extirpated from islands over 100 ha, where stoats maintained a resident population.
Understanding the behaviour of invasive predators is an important step in developing effective predator control techniques. Stoats (Mustela erminea), introduced to New Zealand in the 1880s, are major predators of indigenous birds in forest, wetland, and coastal habitats, and are an emerging threat to alpine biodiversity. Stoats have recently been found to prey upon rock wrens (Xenicus gilviventris), New Zealand’s only truly alpine bird species. We monitored 32 rock wren nests using motion activated infrared (IR) cameras from 2 locations in the Southern Alps over 3 breeding seasons, 2012-2015. The behaviour of stoats that preyed upon 13 rock wren nests was quantified to describe how they behaved around rock wren nests, and to determine whether understanding these behaviours could lead to improved predator control to help to protect this vulnerable bird species. Stoats usually hunted alone. They could reach nests on cliffs and on the ground equally easily by climbing or jumping to them. Rock wren nests were attacked most frequently during the day (85% of nests) and at the chick stage in their life cycle, making this their most vulnerable stage. We suggest that this is because stoats are attracted to nests by the auditory cues of chicks calling out for food. Nests were rarely visited by stoats before or after the observed predation events. Stoats left little evidence of nest predation events beyond enlarging nest entrances. There was no indication that IR cameras or the actions of field workers affected predation behaviour, although some stoats clearly knew the cameras were there. There is an urgent need to deploy effective stoat control to recover rock wren populations. Control should focus on cliff habitats as well as on more accessible ground nests, and, if resources are limited, should primarily focus on the nestling stage. Future research could trial auditory lures to attract stoats to traps, and determine the vulnerability of rock wrens to predation outside the breeding season.
Kākāpō (Strigops habroptilus) are the only parrot species known to have a lek-based mating system. In competing for mating opportunities with females, males can fight intensely with one another, sometimes with fatal consequences. Males may have evolved more deeply hooked bills and raptorial claws than females if these confer advantage in conflicts with other males. We studied bill and claw shape in 28 museum specimens using geometric morphometrics and found no sex differences. While no claw shape sex differences were identified, we did find kākāpō lateral claws are significantly more hooked than their medial toe claws which are flatter. Claw shape in other parrot species has not yet been analysed via geometric morphometric methods, it is therefore unknown whether this claw-shape configuration is unique to kākāpō.
As ecosystem engineers, petrels are integral to ecological restoration schemes seeking to restore land sea nutrient pathways. Yet the current ranges of many petrel species are vastly reduced due to marine and terrestrial threats. Chick translocation is a demonstrated management tool for establishing seabird populations but is dependent on detailed knowledge of species breeding biology. We studied the breeding biology of white-faced storm petrel (Pelagadroma marina maoriana) on Burgess Island, Hauraki Gulf, northern New Zealand, and undertook an onsite chick translocation to investigate the efficacy of current petrel translocation practices for this relatively small species. During our study, breeding extended from August 2011 to February 2012 with hatching occurring on 6 December ± 1.2 days, a chick rearing period of 68.1 ± 0.9 days and fledging on 12 February ± 1.2 days. There was no desertion period by provisioning adults and burrow emergence began 2–6 nights before fledging. Chick growth was typical of Procellariiformes with chick mass (mean = 66.2 ± 1.7 g) peaking at 12.2 ± 1.7 days before fledging. There was no age-related change in the nightly probability of provisioning (0.54) or meal mass (mean = 7.8 ± 0.3 g). Translocated chicks fed a sardine puree diet for 11–20 days before fledging had significantly lighter fledging weights than a control group of adult provisioned chicks, but did not differ in wing length or the duration of burrow emergence before fledging. Our data suggest that translocations of white-faced storm petrel using supplementary feeding of chicks may be possible using slightly modified current feeding practices and could provide an option for expanding populations of endangered storm petrels.
Nocturnal surveys for collared petrel (Pterodroma brevipes) indicate significant variation in the number of birds reported by site, time of year, and survey method. Collared petrels were recorded at 3 new islands within Fiji in 2011. These records indicate that locating collared petrels requires focussed survey effort, although they do not definitively confirm breeding on the islands, for which ground-based searches would be required. When visiting sites where there has been no recent evidence of collared petrel breeding, surveys should be undertaken between February and April (at the start of the breeding season), should use an active method of survey comprising both light for attraction and playback and/or with ‘war whooping’, and should be repeated at a number of sites before concluding that an island holds no breeding birds.
Orange-fronted (Cyanoramphus malherbi) and yellow-crowned parakeets (C. auriceps) are sympatric congeners that are secondary cavity nesting species, with the former being critically endangered. Both currently inhabit anthropogenically-modified Nothofagus forest. We compared the characteristics of nest sites in both species and found the majority of nest site parameters (tree height, height of hole above ground, DBH, tree condition and aspect) were similar. However, orange-fronted parakeets selected nest cavities with a significantly narrower entrance, and when situated in red beech (Nothofagus fusca), nest entrances were significantly smaller in area than in yellow-crowned parakeets. As the male orange-fronted parakeet is smaller in body mass than the male yellow-crowned parakeet (only males feed nestlings when laying multiple clutches), the difference in nest hole size may simply indicate that they are capable of utilising smaller entrances. We also found that orange-fronted parakeets selected nest holes in standing dead trees more frequently and nest sites in silver beech (N. menziesii) less frequently than expected. While the lack of differences in nest site characteristics suggests some interspecific competition may be occurring between these species (i.e., they occasionally use the same nest holes), it is difficult to establish this experimentally and to determine whether these differences are artefacts of former niche separation in unmodified forest.
A 15,000 ha low-intensity stoat (Mustela erminea) trapping network was established in the Murchison Mountains in 2002, primarily to protect the last natural population of the critically endangered takahe (Porphyrio hochstetteri). We compared the productivity and survival of threatened southern brown kiwi or tokoeka (Apteryx australis) living in 3 valleys that were covered by this trapping network with those in a nearby valley that was left untreated. Chick survival to 6 months old was significantly higher in the trapped areas (37%) than in the untrapped area (19%). This doubling of chick survival was sufficient to change the rate of population growth, as derived from Leslie matrix analyses, from a projected decline of 1.6% per annum without management to a projected increase of 1.2% per annum with trapping.