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Seasonal survey of waterfowl (Anatidae), shags (Phalacrocoracidae) and fernbird (Bowdleria punctata) at Te Nohoaka o Tukiauau/Sinclair Wetlands, Otago: July 2015 – July 2018

Notornis, 68 (4), 266–273

M.P. Thompson; B. McKinlay (2021)

Article Type: Paper

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.

Widespread ground-nesting in a large population of feral rock pigeons (Columba livia) in a predator-free and urban native forest

Notornis, 68 (3), 224-233

J.V. Briskie; L. Shorey (2021)

Article Type: Paper

We found widespread nesting on the ground in a large population of feral rock pigeons (Columba livia) in an urban, but predator-free native forest reserve in Christchurch, New Zealand. Ninety-seven percent (n = 77) of rock pigeon nests were located on the ground, with most placed either at the bases of large kahikatea (Dacrycarpus dacrydioides) trees or under a tangle of vines on the forest floor. Clutch size was 2 eggs in all nests, with a hatching success of 93.9% in nests that survived to the hatch stage. Overall nest success was higher (60.0%) than in other populations of rock pigeons, with half of nest failures attributed to culling of the population that occurred during the course of our study. On average, rock pigeons fledged 1.60 chicks per successful nest. No ground nests were located outside the boundary of the predator- proof fence, suggesting pigeons were able to assess predation risk when selecting nest site location. Ground nesting by rock pigeons may be a way to avoid damage to nests in the canopy by strong winds or predation from aerial predators such as harrier (Circus approximans), which also occur in the reserve. Based on density of nests, we estimated a breeding population of 226 to 258 rock pigeons in the 7.8 ha reserve. The high number of pigeons in the reserve highlights the need for further studies on how populations of introduced species of birds in New Zealand respond to control of mammalian predators and the effect this may have on sympatric native species.
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