Justification of Red List Category
This species is classified as Critically Endangered because it has an extremely small breeding range, essentially confined to one island, and evidence suggests that it has experienced a substantial recent population decline linked to bycatch mortality in artisanal fisheries in its principal foraging grounds.
On Española, the breeding population was estimated at c. 12,000 pairs in 1970-1971, 15,600-18,200 pairs in 1994 and at least 34,694 adults in 2001. On La Plata Island, there are probably fewer than 10-20 pairs.
Phoebastria irrorata is endemic to Ecuador. It breeds primarily along the southern coast of Española Island in the Galápagos Islands, and, perhaps, a few pairs breed on La Plata Island off of Manabí province, Ecuador (Harris 1973). Breeding adults travel to the Peruvian upwelling region to feed (Anderson and Cruz 1998, H. Vargas and F. Cruz in litt. 2000, Awkerman et al. 2014), and in the non-breeding season birds move mainly east and south-east into the waters of the Ecuadorian and Peruvian continental shelf to the extreme north of Chile (Tickell 1996, Anderson and Cruz 1998, BirdLife International 2004, K. Huyvaert pers. comm. 2016). Rarely seen north of the equator, they are occasionally sighted off the coasts of Colombia (at least from El Choco) and Panama (Granizo 2002, Jahncke 2007).
On Española, the overall breeding population was considered to have been stable during the 20th Century. It was estimated at c.12,000 pairs in 1970-1971 (Harris 1973), 15,600-18,200 pairs in 1994 (Croxall and Gales 1998, Douglas 1998), and at least 34,694 adults in 2001 (Anderson et al. 2002). Although there has not been a global population estimate since 2001, surveys at two principal breeding sites on Española in 2007 demonstrated a decrease in the number of breeding birds since 2001, and an overall population decrease (including non-breeders) at these sites since 1994 (Anderson et al. 2008). The breeding distribution has changed owing in part to vegetation regrowth following the eradication of goats (Anderson et al. 2002). Breeding no longer occurs at two inland sites, perhaps through redistribution to the coast (Anderson and Cruz 1998, Douglas 1998). On La Plata Island, there are probably fewer than 10-20 pairs (Anderson and Cruz 1998), and long-term data are too limited to assess population trends (Croxall and Gales 1998). In 2001, three adults were seen there with no evidence of breeding and a further 11 non-breeding adults were found on Isla Genovesa (Anderson et al. 2002).
Recent evidence has shown a 2-3% reduction in annual adult survival compared with that in the 1960s, which is thought to have driven recent dramatic declines in the breeding population (Awkerman et al. 2006, J. Croxall in litt. 2006, Anderson et al. 2008). Analysis of birds caught as intentional and incidental take in inshore fisheries has revealed that a disproportionate number of males are taken, which will result in further decreases to the effective population size given that this species has obligate bi-parental care (Awkerman et al. 2006). Even if immediate action was taken to curb adult mortality the population will continue to decline for a decade or so until the current cohort of juveniles reach breeding age (J. Croxall in litt. 2006). Breeding sites may be constrained by the extent and location of take-off points, which are in turn limited by dense vegetation (Gibbs and Woltz 2010).
Behaviour This species breeds annually, arriving at colonies in late March (with males arriving earlier than females and older birds earlier than younger birds) (Harris 1973, Huyvaert et al. 2006, Jahncke 2007), and laying from mid-April to late June. Chicks fledge between late December and early January. Some pairs skip breeding in certain years (Jahncke 2007, Street 2013). The age of first breeding is at four to six years of age or more, but individuals return to colonies, typically late in the season, from two years of age (Hirschfeld 2008, ACAP 2009, Street 2013).
Habitat Breeding Nesting takes place on sparsely vegetated areas with lava surrounded by boulders (Harris 1973) but also, more recently, in thick scrub vegetation (Anderson et al. 2002).
Diet It feeds on squid, fish, and crustaceans (Harris 1973), but scavenging food items disgorged by other species (such as cetaceans and boobies) may be an important feeding strategy (Merlen 1996, Anderson and Cruz 1998). A tracking study showed that during the breeding season, those birds that breed on Española made foraging trips eastwards towards the continental shelf and along the coast of Peru (Awkerman et al. 2014). The small number of birds from La Plata Island made much shorter but more frequent foraging trips to the continental shelf (Awkerman et al. 2014).
Altered temperature regimes associated with climate change poses a major threat. The species has shown susceptibility to past El Niño Southern Oscillation (ENSO) events, in the form of increased adult mortality and increased negative interactions with fisheries under these conditions (Rechten 1986, Awkerman et al. 2006).
The species also suffers from both incidental and targeted capture by the fishery (ACAP 2009). In small-scale Ecuadorian and Peruvian fisheries, Waved Albatross was the most frequent bycatch, caught in demersal and surface longlines and shark driftnets (Mangel 2012). The estimated bycatch rate of 0.11 birds per 1,000 hooks is sufficient to drive significant declines. Males seem more likely to be killed in longline operations, resulting in a female-skewed sex ratio (1.188 females per male; Awkerman et al. 2007) and indicating that bycatch is likely to be a significant source of adult mortality (Street 2013) and reduced effective population size.
Avian pox was recorded in chicks on Española, which subsequently displayed higher mortality than unaffected chicks, although the outbreak was small and population impacts at present unlikely to be significant (Tompkins et al. 2017). Introduced mosquitoes produces distress in birds and is the proposed cause for the observed movement of eggs by parents (frequently resulting in the loss of the egg) and mass abandonment of eggs (Harris 1969, Anderson and Fortner 1988). This threat may be exacerbated by climate change, as increased abundance of mosquitoes Aedes taeniorhynchus have been recorded during warm ENSO years with heavy rainfall.Oil spills have impacted the population in the past and may be a returning threat (Anderson et al. 2003).
Conservation Actions Underway
Española is part of the Galápagos National Park and Marine Reserve. Industrial, but not artisanal, longlining is prohibited in the Galápagos Marine Reserve (Anderson et al. 2003). In 1979, the islands were declared a World Heritage Site. Española is well protected and has no alien fauna (goats having been eradicated in 1978; Anderson and Cruz 1998, Jiménez-Uzcátegui et al. 2007), and tourism is well-regulated (Carboneras 1992). A tortoise breeding programme has led to the release of over 2,000 tortoises on the island in the last 30 years; as the only native herbivore these animals may play a key role in vegetation control and maintaining suitable habitat for breeding albatrosses (Jahncke 2007). La Plata Island is part of Machalilla National Park, but is insufficiently protected (Carboneras 1992). The Agreement for the Conservation of Albatrosses and Petrels (ACAP) organised workshops in Peru and Ecuador in 2007 and 2008 to develop an Action Plan for Waved Albatross. There are proposals to protect more marine key biodiversity areas within the Galápagos Marine Reserve by amending the existing marine zoning scheme to reduce the impact from fishing (Edgar et al. 2008).
The Charles Darwin Foundation (CDF), Galapagos National Park Directorate (GNPD) and collaborators are carrying out long-term monitoring and on-going research using mark-recapture studies to determine changes in survival and reproduction, and investigating the relative importance of potential threats (heavy metals, diseases, climate change and human interaction).
Conservation Actions Proposed
Enumerate the breeding population regularly and establish a baseline to ascertain trends. Further evaluate extrinsic population threats (e.g., disease, plastic ingestion, contaminants). Further evaluate the threat of incidental and deliberate take in fisheries within the species's range; and control levels of hunting. Adopt appropriate interim techniques to minimise bycatch. Improve protection for the Isla de la Plata colony.
90 cm. Medium-sized albatross with white head, tinged buff-yellow on crown and nape. Chestnut-brown upperparts finely barred, coarser over rump. Brown upperwing, back and tail. Whitish breast, remainder of underparts barred, like upperparts. Whitish underwing, browner axillaries, brown around margins. Dull yellow bill. Bluish feet project beyond tail in flight. Juvenile like adult but with whiter head.
Text account compilers
Moreno, R., Nel, D., Small, C., Stattersfield, A., Stuart, A., Sullivan, B., Symes, A., Ashpole, J, Butchart, S., Calvert, R., Fjagesund, T., Bird, J., Anderson, O., Hermes, C., Martin, R.
Allport, G., McClellan, R., Croxall, J., Vargas, H., Anderson, D., Jiménez-Uzcátegui, G., Cruz, F., Huyvaert, K.
BirdLife International (2021) Species factsheet: Phoebastria irrorata. Downloaded from http://www.birdlife.org on 22/01/2021. Recommended citation for factsheets for more than one species: BirdLife International (2021) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 22/01/2021.