Justification of Red List Category
Long-term monitoring indicates that the population is fluctuating, primarily as a result of marine perturbations that may be becoming more extreme through climate change. These perturbations have caused an overall very rapid population reduction over the last three generations (31 years). In addition, the species has a small population and is restricted to a very small range, with breeding confined to a few locations. These factors qualify it as Endangered.
Although the population is small, the exact size is unknown: it could have been as low as 700 individuals in 1983 or as high as 10,000 in 1971. The population in 2009 was likely between 1,800 and 4,700 individuals (Boersma et al. 2013, 2015). The El Niño Southern Oscillation (ENSO) events in 1971-1972, 1982-1983 and 1997-1998 reduced the number of penguins to half of the number seen in the early 1970s (Boersma 1977; Mills and Vargas 1997; Boersma 1998; Ellis et al. 1998; Vargas et al. 2005, 2006, 2007; Boersma et al. 2013, 2015). A head count of 1,009 Galápagos Penguins in 2007 was half the number counted in 1970 (2,020) and 1971 (2,099) (Boersma et al. 2013, 2015).
The species declined by 60% between 1970 and 2004. Assuming that declines are continuing at this rate to the present day, this would equate to a reduction of 57% over the past three generations (31.2 years). A population reduction of more than 80% is predicted in the next 100 years, if the frequency of strong El Niño events is doubled from the current rate of 5% to 10% under future climate change scenarios (Vargas et al. 2007). This equates to a reduction of up to 39% over the next three generations. Under the ‘‘Current El Niño"-scenario, based on the frequency of El Niño events recorded in the Galápagos between 1965 and 2004, a probability of extinction of approximately 30% within the next 100 years is estimated (Vargas et al. 2007).
Spheniscus mendiculus is endemic to the Galápagos archipelago, Ecuador. It is the most northerly species of penguin, breeding on Isabela, Fernandina, Floreana and Santiago islands, and several offshore islets. Approximately 95% of the Galápagos Penguin population is found on Isabela and Fernandina islands in the western part of Galápagos (Vargas et al. 2007; Boersma et al. 2013, 2015). Isabela is home to the majority of Galápagos Penguins, but there are severe problems with introduced species, including rats and cats. The main breeding range stretches along the coast of the two westernmost islands, encompassing approximately 400 km of coastline, where 96% of all nests are found (Steinfurth 2007). During the breeding season, penguins forage close to the shore and nest sites, while there is evidence that non-breeding adults move further offshore and longer distances away from the colony. The marine habitat use by juvenile birds is largely unknown (Boersma 1977; Vargas et al. 2005; Steinfurth 2007; Steinfurth et al. 2008). Vagrants have been recorded from Panama (Eisenmann 1956; Ridgely and Gwynne 1976).
With its range located on the equator, the Galápagos Penguin is the most northerly breeding penguin species. Nonetheless, its distribution is highly linked to the cool and nutrient-rich oceanic waters in the western Galápagos archipelago, that allows for a high density of prey when upwelling is present (Boersma 1977, 1978; Palacios et al. 2006; Vargas 2006; Boersma et al. 2013, 2015; Karnauskas et al. 2015). It nests just above sea level and forages close to shore and at relatively shallow depths (Mills 2000; Steinfurth et al. 2008; Boersma et al. 2013, 2015). Galápagos Penguins breed throughout the year, coinciding with increased upwelling (Boersma 1978; Steinfurth 2007; Boersma et al. 2013, 2015). During chick rearing, adult birds move up to 23.5 km from the nest, concentrating foraging within 1 km of the shore (Steinfurth 2007). While breeding Galápagos Penguins show high site fidelity, non-breeding individuals (adults and juveniles) tend to migrate away from their colony (max. 64 km) (Boersma 1977; Vargas et al. 2006; Steinfurth 2007). After fledging, if food is available, adults continue to feed fledglings (Boersma et al. 2017).
The ecological relationships between penguins and their prey varies depending on the frequency and strength of upwelling, making the population size unknown and extremely difficult to estimate. This is due to the highly variable strength of cool, mineral-rich upwelling water.
In recent decades, this species has been influenced primarily by the effects of ENSO on the availability of shoaling fish (Boersma 1978, 1998; Vargas et al. 2005, 2006, 2007; Boersma et al. 2013, 2015). In 1982-83 and 1997-98, head counts declined by 77% and 65%, respectively. The annual penguin head count then increased, so the population may have been relatively stable. Then head counts further increased slightly until 2009, when the last complete count was done. Despite these increases, head counts were still 48% below the pre-El Niño head counts (Mills and Vargas 1997; Boersma 1998; Ellis et al. 1998; Vargas et al. 2007). Recovery from the 1982-1983 ENSO may have been slowed by the lower frequency of La Niña cold water events and above average surface water temperatures (Boersma 1998). Also, ENSO events may have a disproportionate impact on females, which could result in a biased sex ratio, making population recovery slower (Boersma 1998; Vargas et al. 2007). Climate change may lead to an increase in the frequency of ENSO events in the future (Trenberth and Hoar 1996, 1997; Houghton et al. 2001; Karl and Trenberth 2003), which will also reduce the species's resilience to other threats, such as disease outbreaks, oil spills and predation by introduced predators (Boersma 1998; Boersma et al. 2005; Steinfurth and Merlen 2005; Travis et al. 2006; Vargas et al. 2007). Locations of upwelling vary with climate variation (Karnauskas et al. 2016). The Galápagos cold-water pool has been intensifying and expanding northward since 1982, which may shift the mean position of the Equatorial Undercurrent and would likely impact the penguins (Karnauskas et al. 2015).
Local fishing boats operating in inshore waters in the western part of the archipelago are documented as incidentally drowning Galápagos Penguins due to floating nets (Cepeda and Cruz 1994). Increasing demand for bait fish could dramatically increase inshore bait fisheries, which may exacerbate these problems (Trathan et al. 2014). Contamination from oil spills poses another severe potential threat.
Non-native predators like rats, cats, and dogs remain problems on many islands. Predation by one individual feral cat (Felis catus) at one of the species's breeding sites resulted in adult mortality of 49% (Steinfurth 2007). Feral cats are also vectors of parasites, such as Toxoplasma gondii, which has recently been found in Galápagos Penguins with still unknown consequences (Deem et al. 2010; Boersma et al. 2013, 2015). Mosquitoes (Culex quinquefasciatus) arrived in the Galápagos islands in the 1980s as a result of human actions (Whiteman et al. 2005). Since they are vectors for avian malaria and West Nile Virus, and penguins in the genus Spheniscus are highly susceptible to these diseases, these insects represent a potential new threat for the Galápagos Penguin (Travis et al. 2006). The Plasmodium blood parasite has been found in Galápagos Penguins (Levin et al. 2009, 2013). Many of the above threats are potentially exacerbated by an ever-expanding human population and an increase in tourists visiting the islands.
Conservation Actions Underway
The whole population of Galápagos Penguins is found within the Galápagos National Park and Galápagos Marine Reserve (GMR), which is managed by the Galápagos National Park Service (GNPS) and the authorities of the GMR. Access to breeding sites is strictly regulated, take of adults and/or eggs is prohibited and research is only possible with special permission. Introduced predators are to be controlled by the GNPS. On a few islands, introduced predators have been successfully eradicated. Research projects have been encouraged by the GNPS with the aim to protect this species by determining its marine needs and strengthening local capacity in scientific research, practical conservation, decision-making and sustainable management for this species (Vargas 2006; Steinfurth 2007). To create more high-quality breeding habitat for the penguins, artificial nests were built in 2010 and some are being used (P. D. Boersma pers. obs.). Research on the value of these constructed lava nests and marine protected areas continues. To protect penguins, the President of Ecuador in February 2016 recommended that no-take (fishing) zones are to be established within the GMR at three sites where penguins breed (Elizabeth Bay, Bartolomé and Sombrero Chino islands and Caleta Iguana). iGalápagos.org engages people in taking pictures of penguins to determine when and where penguins are molting and breeding, in order to gain more information on the breeding cycle and to raise awareness for the precarious population status. The Galápagos Conservancy, together with the National Park, has developed an educational program for children in the islands.
53 cm. Small, black-and-white penguin. Black head with white border from behind eye, around black ear-coverts and chin, joining up on throat. Blackish-grey upperparts. Whitish underparts with two black bands across breast, lower band extending down flanks to thigh. Juvenile differs in wholly dark head, greyer on side and chin, and lacks breast-band.
Text account compilers
Hermes, C., Boersma, P., Cappello, C.
Allinson, T, Benstead, P., Bird, J., Boersma, P., Calvert, R., Clay, R.P., García Borboroglu, P., Hernan, V., Karnauskas, K., Lascelles, B., Merlen, G., Moreno, R., Parker, P., Steinfurth, A. & Vargas, H.
BirdLife International (2021) Species factsheet: Spheniscus mendiculus. Downloaded from http://www.birdlife.org on 16/01/2021. Recommended citation for factsheets for more than one species: BirdLife International (2021) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 16/01/2021.