Snares crested penguins Eudyptes robustus population estimates 2000–2013

Abstract

New Zealand (NZ) is an internationally significant area for penguins. All NZ penguin species are listed in 'at risk' threat categories. The naturally uncommon Snares crested penguins (Eudyptes robustus), which are restricted to NZ subantarctic islands, are highly susceptible to localised stochastic events and human activities. There has been uncertainty about population size and trends for Snares crested penguins. We surveyed the nest abundance and distribution of Snares crested penguins on Northeast (NE) and Broughton Islands, Snares Island group, from late September to early October in 2008, 2010 and 2013 and compared results with a survey from 2000. Counts of all nests (nests with eggs and total observed nests) within all colonies around the islands were undertaken. In 2008, 19 845 ± 29 nests with eggs and 24 666 ± 38 total nests were counted from 111 colonies. In 2010, 25 525 ± 21 nests with eggs and 30 672 ± 26 total nests from 117 colonies were counted while in 2013, 25 149 ± 39 nests with eggs and 29 009 ± 45 total nests from 119 colonies were counted. Penguin nest numbers at the Snares appear to be stable overall when compared with the 2000 survey, which gave 28 396 nests with eggs (direct counts) and 30 607 total nests from 112 colonies. However, 2008 appears to be a year with considerably lower numbers of nests compared with other years. This apparently stable population is in contrast to most other crested penguins in the world. Given the extremely restricted distribution of Snares crested penguins and potential for a rapid catastrophic decline, we recommend surveys be continued at regular intervals in order to detect a significant decline and allow management measures to be implemented if needed.

Assessing the population trend and threats to New Zealand’s Fiordland crested penguin using counting and demographic modelling approaches

“…However, this may not always be the case because a number of penguin species show large population changes over short temporal scales, and these events are not reflected in any longterm trends, indicating that birds are alive but not at colonies every year (e.g. northern rockhopper penguin, Cuthbert et al 2009;southern rockhopper penguin, Crawford et al 2008;Baylis et al 2013b; Snares crested penguin, Hiscock & Chilvers 2016;macaroni penguin, Trathan et al 2012; gentoo penguin Pygoscelis papua, Baylis et al 2013a). The Fiordland crested penguin may also not attempt to breed every year because many monitoring sites showing considerable variation between years in the number of nests detected.…”

Ancient DNA of crested penguins: Testing for temporal genetic shifts in the world’s most diverse penguin clade

“…Surveys of E. sclateri suggest that populations were stable until 2011, but have subsequently declined by 19% (Hiscock and Chilvers, 2014). In contrast, Warham (1974), Mattern (2013) and Hiscock and Chilvers, (2016) suggested that E. robustus populations have remained stable. By contrast, the extent to which any such demographic shifts might have impacted the genetic composition of Eudyptes populations remains unclear.…”