Abstract: Birds were surveyed once per season over three years from 2015–2018 at Te Nohoaka o Tukiauau/Sinclair Wetlands, Otago. Eight species of waterfowl were observed, including four native species: New Zealand scaup (Aythya novaeseelandiae), Australasian shoveler (Anas rhynchotis), paradise shelduck (Tadorna variegata), and grey teal (Anas gracilis). Native species made up 68% of all waterbirds counted. New Zealand scaup dominated at 53%. The highest total number of birds counted was 1167 in winter 2015, and the lowest was 76 in spring 2016. The counts for some species varied greatly from year to year and each species showed some seasonal variation. It appears that more waterfowl are using the lagoons now than 15 years ago. Shag numbers were never greater than 8 individuals. The estimated density of fernbird (Bowdleria punctata) along a 750 m transect varied from 1.0/ha in winter to 2.7/ha in summer. This survey of waterfowl, shags and fernbird provides a reference against which future comparisons investigating long-term trends in bird populations at the Sinclair Wetlands can be made.
Enderby Island is a much-visited small island in the New Zealand subantarctic, and is an important area for birdlife. However, despite this, the bird community of Enderby Island has never been systematically described. We summarise bird records on Enderby Island from 1840 to 2018. Using these data we describe the bird community with an emphasis on resident species, and compare the frequency of sightings before and after eradication of invasive mammals in 1993. We also investigate trends in bird sightings from 1992 to 2018. There was a significant increase in the sightings of some species, including tui (Prosthemadera novaeseelandiae) and silvereye (Zosterops lateralis), and a significant decrease in others, including white-fronted tern (Sterna striata). Some species, such as New Zealand falcon (Falco novaeseelandiae) and Auckland Island snipe (Coenocorypha aucklandica aucklandica), have recovered successfully following dramatic historical declines. We hypothesise that these trends in sightings are driven by changes in human exploitation, the introduction and subsequent eradication of browsing mammals and mice, changes in the abundance and structure of the invertebrate community, and changes in vegetation cover. However, we believe that trends in sighting rates of southern royal albatross (Diomedea epomophora) may be an artefact of changes in visitor behaviour following the construction of a boardwalk, rather than changes in the species’ abundance.
We undertook a survey of coastal wetlands in Canterbury (NZ) during a widespread river flooding event in Spring 2013 to quantify numbers and distribution of wrybill (Anarhynchus frontalis). We found 740 birds, of which 685 (92.6%) were at Lake Ellesmere/Te Waihora. We calculate that 15.8% of the estimated effective wrybill breeding population were displaced from breeding rivers by floods at this time. Our findings support the evaluation by Dowding & Moore (2006) that the network of wetlands along the Canterbury coast appears to be of critical importance to wrybill as breeding season flood refugia.
Ten white-headed petrels (Pterodroma lessonii) from Adams Island, Auckland Islands, were tracked during 2011–14 using miniature geolocators, in the first study to examine the at-sea movements and key foraging areas of this pelagic seabird. Data revealed extensive migrations west to South Africa and east into the central South Pacific Ocean. The birds returned to colonies Aug–Oct. Median departure on pre-laying exodus was 24 Sep. Birds were away for up to 77 days during pre-laying and moved west towards the Indian Ocean. Laying occurred 24 Nov–10 Dec. The first major incubation shifts by males and females were c. 19 days in duration. The maximum foraging range during incubation was 5,230 km from the colony, the most distant recorded by any seabird during this breeding stage. After eggs hatched in January, some birds foraged off Antarctica in sea temperatures down to –1°C. Birds spent the inter-breeding period in disjunct areas (off South Africa, south of Australia, Tasman Sea, and South Pacific Ocean). This study revealed an unusual courtship behaviour not recorded previously in other seabird species. Females returned from distant oceans to spend just a few days ashore in the pre-laying period before leaving the breeding site until the following spring. The males also skipped breeding at the same time as their mates, but returned earlier in the season. The new knowledge gained about the breeding activity of this species will assist with future population assessments.
Adams Island (9,693 ha) is the second-largest island in the Auckland Islands group, and the largest island in New Zealand on which introduced mammals have never become established. Adams Island is forested on the northern sheltered parts of its coastline, and has shrubland, grassland, and fellfield at higher altitudes, and herb-field in fertile open sites. Sheer cliffs dominate the exposed, southern side of the island, and above them, narrow shelves support lush herb-fields. This diversity of habitat in close proximity supports unique communities of birds, with most species in remarkable abundance due to the absence of introduced predators. With the notable exception of the Auckland Island merganser (Mergus australis), the island’s birdlife is close to what it would have been in pre-human times, and includes high densities of species that are now rare or missing on nearby Auckland Island. This paper describes the island, the history of ornithological exploration, and the past and current state of the avifauna. The 48 extant bird species recorded from the island comprise 22 land birds and 26 seabirds, of which 34 species (16 land birds and 18 seabirds) have been recorded breeding or are likely to be breeding there. Eight species introduced to New Zealand have also made their way to Adams Island, and six probably breed there.
The wrybill (Anarhynchus frontalis) is an endemic plover that breeds only in braided rivers east of the main divide in the South Island of New Zealand. It is threatened by a range of factors, including loss and degradation of habitat, flooding, and predation. We monitored wrybills in 2 sites in the Tekapo River and 2 in the Tasman River in the Mackenzie Basin, South Canterbury, during 3 breeding seasons (1997/98–1999/2000). We aimed to compare survival and productivity between areas with and without trapping (mammalian predator control) to determine whether predator control was associated with higher survival and/or breeding success of wrybills. In the Tekapo River, results were similar between trapped and un-trapped areas, suggesting that control had little effect. In the Tasman River, there were large differences between the two sites and trapping appeared to be beneficial; in the upper river (un-trapped), productivity and survival were very low and in the lower (trapped) site they were high. Over the whole study, 67.3% of nests hatched, and depredation was the largest cause of nest failure. Fledging success (the proportion of chicks hatched that fledged) averaged 35.4%. Losses at the chick stage were higher than at the egg stage, and there was only a weak correlation between nesting success and overall breeding success; we therefore caution against the use of nesting success as a proxy for overall breeding success. Productivity averaged 0.49 chicks fledged per pair over the whole study; when the very low values from the upper Tasman site were excluded, productivity averaged 0.61. Survival of adult male wrybills was lower than survival of females in all four study sites. Measurement of adult survival is important in determining the full effect of predator control (and in determining population trends) but is often overlooked. At the time of our study, wrybill populations in 3 of our 4 study sites appeared not to be self-sustaining and, in the absence of immigration, were in decline. A number of factors, including depredation by mammals, can affect breeding success. Trapping may be beneficial, but temporal and geographic differences in predator densities, as well as variability in other threats (such as flooding and levels of avian predation) mean that predicting when and where mammalian predator control may benefit wrybills is currently difficult.