Data Zone
Justification of Red List category
This species occupies an extremely small breeding range restricted to only a few islands. The population has undergone a population increase due to previous conservation efforts. Albeit, based on threats such as invasive species, fisheries and climatic events, habitat quality is thought to be undergoing a continued decline. It consequently qualifies as Near Threatened. If ongoing and potential threats continue to degrade the species's habitat however, it may warrant uplisting in the future.
Population justification
Based on colony observations, breeding populations are thought to occur in two main regions in Peru and Chile (C. Zavalaga in litt., Jahncke and Goya 1998, Valverde 2006, Guerra-Correa et al. 2011, Cristofari et al. 2019, Fernández et al. 2019, A Simeone in litt. 2020). In Peru, 11,100 breeding pairs were observed on Isla La Vieja in 1995, 1,109 on Isla San Gallán in 1996, and 10 on Corcovado Island in 2005. In 2010, 36,450 pairs were recorded on Isla La Vieja alone, indicating a significant increase since the mid-90s (C. Zavalaga in litt. 2010). There are an unknown number on Guañape Sur (A. Simeone in litt. 2020).
In Chile, 8 breeding pairs were observed on Fernández Vial Island (date unknown), 432 on Pan de Azúcar Island in 2012 (although higher counts of 3,317 pairs were observed in 2009 here, such numbers are considered uncertain, with little explanation behind possible inflation in population size), 97 on Isla Grande de Atacama in 2013 (with the small population residing here thought to form a population sink for migrant birds from neighbouring islands; Cristofari et al. 2019), 10,789-11,934 on Isla Choros during 2013-2014, and 40 on Isla Pájaros II in 2014 (Fernández et al. 2019, A. Simeone in litt. 2020).
The overall population size remains high ,with the Chilean population currently estimated to number 12,500 breeding pairs (with 95% on Choros Island; Fernández et al. 2019) and the Peruvian population tentatively thought to number at least 40,000 pairs (following observations of 36,450 breeding pairs on Isla La Vieja alone; C. Zavalaga in litt. 2010). This roughly equates to 52,500 pairs, rounded here to 50,000 pairs overall and converted to 100,000 mature individuals. The species's colonies are considered to be genetically isolated, with low migration rate due to its highly philopatric nature (Cristofari et al. 2019, A. Simeone et al. in litt. 2020).
Trend justification
The total population of the species in Chile is thought to have seen a continued increase since 1980 until at least 2013, where between 2010 and 2014, a 43% increase in breeding pairs were observed on Choros Island alone (Fernández et al. 2019). A contributing factor is likely to have been due to successful rabbit eradication programmes (C. Wolf and N. Holmes in litt. 2020). An eradication programme in 2013 is also thought to have led to an increase in the island's sub-colonies, from 28 in 2010 to 90 in 2018 (C. Wolf and N. Holmes in litt. 2020). Range re-expansion and local population growth has similarly been observed on many other Chilean islands, with sightings of non-breeding individuals in northern Peru and rapid growth on La Vieja Island, Peru, also recorded (Cristofari et al. 2019).
It is however worth nothing that the observed population on Choros Island declined slightly between 2013 and 2014, and is observed to have declined since then to 2019 (per Fernández et al. 2019, C. E. Fernández et al. in litt. 2020). Reasons for this decline are currently unknown and yet to be investigated (C. E. Fernández et al. in litt. 2020), and it is unclear whether they represented a fluctuation or a sustained decline. As such, it is untenable to currently use localised declines to define the current trend of the global population.
Similarly, whilst the species continues to be affected by a number of factors, 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, immense local conservation efforts have certainly led to a positive change on the overall breeding population (Fernández et al. 2019). Hence, whilst the potential overestimation of growth rates in historical data and changes in methodology possibly exaggerated trends (C. E. Fernández et al. in litt. 2020), the global population is tentatively thought to be slowly increasing. Due to a recent increase in the house mouse population on Isla La Vieja (C. E. Fernández et al. in litt. 2020) however, as well as observed declines on other breeding islands (such as Choros; Fernández et al. 2019, C. E. Fernández et al. in litt. 2020), population trends must continue to be carefully monitored. The global population may therefore be revised in the future if localised declines were to accelerate beyond population recovery.
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. Overall, the largest breeding colonies are attributed to the La Vieja-San Gallán islands in Peru and Choros islands in Chile, separated by 1,300 km (C. E. Fernández et al. in litt. 2020). 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 the 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, a 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).
Recently, new colonies have been found on Lobos de Afuera and Corcovado suggesting the species's reappearance there (E. Frere in litt. 2020). In Chile, 220 nests were also 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). However, high densities of nests were recorded on 4 islands north of Chile (Chañaral, Damas, Choros and Gaviota islands), with suggested densities of up to 1,400 individuals per hectare (Cruz-Jofré and Vilina 2014).
It has been recorded throughout the year near Isla Chañaral, and may still breed there or on small islands to the south (Vilina 1992). A more recent survey found evidence of the species entering artificial burrows on Chañaral, with footprints observed in social attraction sites; however, no nesting has yet been observed (C. Wolf and N. Holmes in litt. 2020).
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). Its philopatric nature may additionally suggest that rescue by migration is untenable, with the population thus vulnerable to ongoing anthropogenic pressures (Cristofari et al. 2019). Bycatch by artisanal fisheries represents a threat to the species, but previously speculated impact of the exploitation of anchovies throughout the species's 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). However, within a 14-year period, c. 178 Peruvian Diving-petrels were found dead due to interactions with fisheries suggesting that competition with fisheries remain persistent (C. E. Fernández et al. in litt. 2020). The species can also be hunted for food on some islands (M. de L. Brooke in litt. 1999). Other human-driven threats include tourism, egg collection and light pollution (Simeone et al. 2003, Cristofari et al. 2019). Lack of adequate biosecurity measures (such as unmanaged visits to some breeding sites) also remains a potential threat due to potential introduction of invasive species (C. Wolf and N. Holmes in litt. 2020).
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); Chañaral Island alone may have held over 100,000 pairs prior to fox introduction (A. Simeone et al. in litt. 2020). Cats Felis catus and rats Rattus spp. are present on several islands within the species's range (Jahncke et al. 1999) and likely depredate adults and nests respectively. Fisherman may also chase rabbits (Oryctolagus cunniculus) which could inadvertently destroy burrows (Simeone et al. 2003). House mice (Mus musculus) have moreover seen a rapid increase in recent years on Isla La Vieja (C. E. Fernández et al. in litt. 2020). 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). These invasive mammals may also prohibit re-colonisation of some islands (C. E. Fernández et al. in litt. 2020).
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). Two larger harbors are however planned to be built in the future to help with guano mining, likely to affect coastal foraging, nesting areas, and increased disturbance due to light (Cristofari et al. 2019).
Conservation Actions Underway
All colonies are in reserves but only La Vieja has trained guards (Jahncke et al. 1999). The Humboldt Penguin National Reserve additionally includes Isla Choros and the surrounding marine area (Cristofari et al. 2019). Pan de Azúcar is declared a National Park, with a management plan granted in 2002, Choros is also a National Reserve with a management plan granted in 2009, whilst Grande de Atacama is a Coastal Marine Protected Area (Fernández et al. 2019). There have been searches for additional colonies in Chile (Vilina 1992). Strong biosecurity measures are in place on Choros and Chañaral Islands (due to the National Forest Corporation's [CONAF] management of the Humboldt Penguin National Reserve), albeit other breeding sites may be lacking in this (C. Wolf and N. Holmes in litt. 2020). A rabbit eradication programme conducted on Choros Island in 2013 was observed to have led to higher densities of the species post-eradication (C. Wolf and N. Holmes in litt. 2020). Similar eradication programmes were also carried out on Chañaral Island in 2016 (C. Wolf and N. Holmes in litt. 2020). 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). Island Conservation and Chile's Forest Service (CONAF) are attempting to attract nesting on Chañaral Island by decoys, artificial nests, and play-back (A. Simeone et al. in litt. 2020), albeit breeding has not yet been observed (American Bird Conservancy 2020, Vilches et al. 2020).
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
Fernando, E., Elliott, N., Hermes, C., Martin, R.
Contributors
Luna-Jorquera, G., Anderson, O., Bennett, S., Bird, J., Brooke, M., Calvert, R., Capper, D., Clay, R.P., Cristofari, R., Fernández, C., Frere, E., Holmes, N, Howell, S., Lascelles, B., Plaza, P., Simeone, A., Stuart, A., Stuart, T., Wolf, C. & Zavalaga, C.
Recommended citation
BirdLife International (2024) Species factsheet: Peruvian Diving-petrel Pelecanoides garnotii. Downloaded from
https://datazone.birdlife.org/species/factsheet/peruvian-diving-petrel-pelecanoides-garnotii on 22/11/2024.
Recommended citation for factsheets for more than one species: BirdLife International (2024) IUCN Red List for birds. Downloaded from
https://datazone.birdlife.org/species/search on 22/11/2024.