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While Isla Chañaral (29°02’S) in Chile has long been recognized as one of the most important breeding islands for the Humboldt penguin, its population size reportedly never exceeded 3,500 breeding individuals in the last two decades. However, in 2002 a one-day survey found that the population size on Isla Chañaral may be considerably higher than that and may even exceed the world population estimate for the species (3,300 - 12,000 birds). Between 9 and 14 February 2003 we conducted a population census on Isla Chañaral to determine the number of Humboldt penguins present on the island. Two different census methods were used to assess the population size. Terrestrial or surface counts were used to survey penguins on open plains or beaches. Small area surveys of randomly established counting quadrates were conducted to assess the number of penguins inside nests as well as total number of nests. Results from small area surveys were extrapolated using surface size ratios of counting quadrates vs. entire nesting sectors. From the surface counts and small area surveys we determined that approximately 22,000 adult Humboldt penguins, 3,600 chicks and 117 juveniles were present on the island during the survey. The results were higher than any previously published population estimate, which range from 146 to 6,000 individuals. We conclude that natural processes alone cannot account for a population increase of this magnitude. Furthermore, our results correspond well with recent publications that suggest that Humboldt penguin numbers might have been underestimated in the past due to inconsistent census methods. We are concerned about the current protection status of the island in light of its fragility and importance as the premier breeding location of the Humboldt penguin along its entire distributional range.

The numbers of the endangered Yellow-eyed penguins on New Zealand’s third largest island, Stewart Island, have been declining considerably over last four years, primarily as a result of low reproductive success. Interestingly, Yellow-eyed penguins on adjacent Codfish Island seem to flourish. Here, high nest densities and high reproductive success indicate that the Stewart Island problem is a local issue. Chick starvation on Stewart Island points towards a food related and, thus, sea based problem. Between 2004 and 2006, we compared foraging ranges and diving behaviour of breeding Yellow-eyed penguins from both islands and found that their foraging areas did not overlap. Moreover, the size of the marine areas utilised for foraging by penguins from Stewart Island were only a fraction (ca. 20.4 km²) when compared with the foraging grounds of penguins from Codfish Island (ca. 540.0 km²). As a primarily benthic forager, the Yellow-eyed penguin depends on an intact benthic ecosystem. The foraging activities of penguins from Stewart Island coincide with the only remaining biogenic reefs within their foraging range. Hence it seems likely that the degradation of the benthic habitat by commercial oyster dredging is limiting viable foraging habitat for the penguins and facilitates intra-specific competition for food.

The endangered yellow‐eyed penguin/hoiho (Megadyptes antipodes) predominantly forages benthically within its mainland range and shows high foraging site fidelity. Identifying consistencies in foraging locations can allow effective conservation, especially when managing bycatch risk. This study investigated the at‐sea distribution of penguins breeding on Stewart Island to explore site‐specific foraging strategies and inform fisheries management. During the 2020/21 season, 19 adult breeding yellow‐eyed penguins from Port Pegasus, Paterson Inlet, and Codfish Island were fitted with GPS‐TDR dive loggers to track their movements and diving behaviours. A total of 25,696 dives were recorded across 91 foraging trips. Birds from Port Pegasus reached significantly greater depths, spent longer at the seafloor, and performed longer dives. They also had the smallest foraging distribution, with most activity concentrated inshore. Compared to Port Pegasus, foraging radii and trip lengths were twice as large for Paterson Inlet and four times larger at Codfish Island. Despite differences in available foraging habitat, considerable individual and intra‐site consistency for preferred foraging locations was observed. Localised behaviour and inter‐site differences in dive metrics suggest significant plasticity in foraging ecology across their mainland range; however, individual behaviour and preferred foraging locations were extremely predictable. Thus, risk of mortality from fisheries can be quantified and managed accordingly.

Penguins face a wide range of threats. Most observed population changes have been negative and have happened over the last 60 years. Today, populations of 11 penguin species are decreasing. Here we present a review that synthesizes details of threats faced by the world's 18 species of penguins. We discuss alterations to their environment at both breeding sites on land and at sea where they forage. The major drivers of change appear to be climate, and food web alterations by marine fisheries. In addition, we also consider other critical and/or emerging threats, namely human disturbance near nesting sites, pollution due to oil, plastics and chemicals such as mercury and persistent organic compounds. Finally, we assess the importance of emerging pathogens and diseases on the health of penguins. We suggest that in the context of climate change, habitat degradation, introduced exotic species and resource competition with fisheries, successful conservation outcomes will require new and unprecedented levels of science and advocacy. Successful conservation stories of penguin species across their geographical range have occurred where there has been concerted effort across local, national and international boundaries to implement effective conservation planning., This work was supported by the WWF-UK and PEW Foundation. SJ is supported by NSF OPP PICA #1643901.