Justification of Red List Category
This species has an extremely small occupied breeding range on four islands. All subpopulations are declining, some rapidly. It consequently qualifies as Endangered.
In Peru, there were c.12,000-13,000 pairs on San Gallán and La Vieja Islands in 1995-1996; these numbers are supplemented by additional, though small, colonies off the coast of Chile.
The species is detrimentally affected by a number of processes including guano extraction and exploitation for food, predation by introduced rats and dogs on breeding islands, incidental bycatch at sea and increasing frequency of El Niño Southern Oscillation events.
Pelecanoides garnotii formerly bred on offshore islands from Isla Lobos de Tierra, Peru, to Isla Chiloé, Chile. It was numerous, e.g. there were c.100,000 pairs, and perhaps more, on Isla Chañaral, Chile, in 1938 (Vilina 1992), but the population has since declined significantly. In Peru, there were c.12,000-13,000 pairs on San Gallán and La Vieja Islands in 1995-1996 (Jahncke and Goya 1998). This is considerably higher than the c.1,500 individuals estimated in the early 1990s, probably because of improved information rather than an actual increase. In May-August 2010 a new survey of La Vieja Islands documented 102,343 active nests (c.95% on La Vieja), of which 36,450 were occupied, indicating at least a three-fold increase in pairs since 1996, and possibly significantly more (C. Zavalaga in litt. 2010). Two small colonies were found on Corcovado Island, Peru in 2005, extending the current breeding distribution c.700 km north of La Vieja, its main breeding centre (Valverde 2006). A colony may also be present again on the Lobos de Afuera Islands where two individuals were sighted in 2003 and 2004 (Figueroa and Stucchi 2008). In Chile, 220 nests were found on Isla Pan de Azúcar in the late 1980s, where 500+ were seen offshore in November 1993 (S. N. G. Howell in litt. 1999), and 300 nests were reported on Isla Choros in the late 1980s, which had increased to an estimated 1,550 active nests in 2001-2003 (Simeone et al. 2003). It has been recorded throughout the year near Isla Chañaral, and may still breed there or on small islands to the south (Vilina 1992).
It excavates deep burrows in thick guano for nesting, but may also burrow in sandy soils or use natural rock crevices. Breeding has been recorded throughout the year (Riveros-Salcedo and Jahncke Aparicio 1990, Jahncke and Goya 1998), with least activity in November. There are two breeding periods, with some evidence that individual birds breed twice annually (Riveros-Salcedo and Jahncke Aparicio 1990, Jahncke and Goya 1998, M. de L. Brooke verbally 2000). In the non-breeding season, it occurs close to breeding islands in the rich upwelling waters of the Humboldt Current. In Peru, it feeds, even in heavily fished areas, on small crustaceans and small fish (mostly larvae) (Jahncke et al. 1999). At La Vieja Island, Peru, Peruvian anchovy Engraulis ringens (33.9%), the small krill Euphausia mucronata (26.8%) and squat lobster Pleuroncodes monodon (24.3%) were the most important prey species (García-Godos and Goya 2006). High monthly variability in the main prey species suggests an opportunistic feeding behaviour associated with prey avaliability (García-Godos and Goya 2006).
El Niño Southern Oscillation events are known to significantly alter the distribution of Peruvian Diving-petrel prey, reducing the diversity of prey items available to the diving-petrel (García-Godos and Goya 2006), as well as altering weather patterns (M. de L. Brooke in litt. 1999). Bycatch by artisanal fisheries represents a threat to the species, but previously speculated impact of the exploitation of anchovies throughout the species' range does not appear to be valid: the birds take smaller fish than targeted by the fishery and appear to respond far more strongly to sea surface temperature variation (García-Godos and Goya 2006). Peruvian Diving-petrels are hunted for food on some islands (M. de L. Brooke in litt. 1999).
Invasive mammalian predators represent another threat. Peruvian Diving-petrels are thought to have been eradicated completely by foxes, Pseudolopex spp., in parts of the range and foxes have subsequently prevented recolonisation of these areas (Vilina 1992). Cats Felis catus and rats Rattus spp. are present on several islands within the species' range (Jahncke et al. 1999) and likely depredate adults and nests respectively. Dogs are present on San Gallan, where they may have played a significant role in reducing the resident population, however, this is a minority of the population (Jahncke et al. 1999).
Mining for guano continues to happen every 5-7 years in La Vieja islands, but the population here has increased in recent decades suggesting that the current harvest regime is not impacting the species. Formerly destructive guano mining is thought to have been the main driver for large reductions in the population size and, if harvesting regimes become less sustainable, may again threaten the persistence of the species (M. de L. Brooke in litt. 1999).
Conservation Actions Underway
All colonies are in reserves but only La Vieja has trained guards (Jahncke et al. 1999). There have been searches for additional colonies in Chile (Vilina 1992). In December 2009, 22 guano islands, 11 peninsulas (guano reserves) and adjacent waters, covering about 140,000 ha including 3 km offshore, were added to Peru’s national protected area system (Harrison 2009).
22 cm. Small plump, black-and-white petrel that flies low and fast on whirring wings. Mostly blackish above and dull white below, with white tips to scapulars forming pale stripe. Browner face and sides to neck. Dusky sides to breast. Similar spp. Magellanic Diving-petrel P. magellani has white fringes to upperpart feathers and characteristic white half-collar extending from throat behind eye to rear of crown.
Text account compilers
Stuart, A., Stuart, T., Bird, J., Anderson, O., Bennett, S., Calvert, R., Capper, D., Clay, R.P., Lascelles, B., Martin, R.
Howell, S., Brooke, M.
BirdLife International (2019) Species factsheet: Pelecanoides garnotii. Downloaded from http://www.birdlife.org on 19/06/2019. Recommended citation for factsheets for more than one species: BirdLife International (2019) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 19/06/2019.