VU
Desertas Petrel Pterodroma deserta



Justification

Justification of Red List Category
This recently split species is listed as Vulnerable because, although it appears to be stable, it has a very small population. It occupies a very small range on only one island when breeding and is susceptible to human impacts, introduced species and stochastic events, which could drive the species towards extinction in a very short time.

Population justification
The breeding population at Bugio has been estimated at 160-180 pairs (Menezes et al. 2010, BirdLife International 2015). Based on these data, the population is placed in the band for 250-999 mature individuals, assumed to equate to c.350-1,500 individuals in total.

Trend justification
The population is suspected to be stable (Ramirez 2008), although the species faces a number of threats and is susceptible to stochastic events and human impacts.

Distribution and population

This species breeds on Bugio in the Desertas off Madeira, Portugal. Based on surveys in 2006-2007, 120-150 pairs were estimated to breed on Bugio (a lower figure than estimates from 2001 of 150-180 pairs), but the population appears to be stable (Ramirez 2008). The most recent estimate puts the population at 160-180 pairs (Menezes et al. 2010, BirdLife International 2015, Ramírez et al. 2015). The tracking of a total of 43 individuals between 2007 and 2013 has cast light on the species’s non-breeding distribution. Individuals remain in the North Atlantic during the pre-laying exodus, incubation and chick-rearing periods, and winter in five areas: two off the Brazilian coast, one around the Cape Verde archipelago, one off the south-eastern coast of the U.S.A., and one in pelagic waters in the central South Atlantic (Ramírez et al. 2013, 2015).

Ecology

The species breeds at 80-300 m, usually in burrows excavated in the soil, although nests can also be found in rock crevices in areas where soil is not present (D. Menezes and P. Oliveira in litt. 2007). Birds return to their breeding grounds in early June. Incubation occurs between mid-July and mid-August and juveniles fledge throughout November-December (D. Menezes and P. Oliveira in litt. 2007, Ramírez et al. 2013, Ramos et al. 2016). 

Threats

The main threat to the species is the loss of burrows and nesting birds to severe storms and subsequent erosion, which are occurring with increasing frequency. However, only a proportion of the colony has previously been affected and this has caused only minor short-term population impacts, suggesting that non-breeders likely buffer the population to a degree. Predation and disturbance by Yellow-legged Gulls Larus michahellis are potential threats on Bugio. Historically, the species has been predated by invasive feral cats and its breeding sites have been affected by habitat degradation caused by introduced goats, rabbits and mice (D. Menezes and P. Oliveira in litt. 2007). These threats were targeted through EU-funds during the period 2006-2010 (LIFE06 NAT/P/000184) and have been monitored since then. These invasive species have not been recorded in the breeding plateau since 2008 (D. Menezes pers. comm. 2016, F. Zino pers. comm. 2016). In the past, this species has been targeted by humans, however this no longer occurs and is thought to be unlikely to return.

Conservation actions

Conservation Actions Underway

A European action plan was published in 1996 (Zino et al. 1996) and its implementation reviewed in 2010 (Barov and Derhé 2011). Since 2006, an eradication programme for rabbits and mice has been in force; it is believed that these species may not longer inhabit Bugio Island, yet no official communication has been made by Natural Park Authorities, so the island is not yet declared alien-free (I. Ramírez pers. comm. 2016). The threat from Larus michahellis is being monitored (D. Menezes and P. Oliveira in litt. 2007). Natural vegetation replanting, together with  anti-erosion blankets and building of artificial nests were all part of a successful EU-funded project (2006-2010, LIFE06 NAT/P/000184). Wardening and monitoring have since been in place on Bugio’s south plateau (Menezes 2007, Menezes et al. 2011), yet an increase in the monitoring effort of both natural and artificial nests is yet needed. Geolocators are being attached to breeding individuals from 2007 onward on a yearly basis to investigate foraging ecology (Ramirez et al. 2013, Ramírez et al. 2015, Ramos et al. 2016). In 2016, GPS-loggers were also fitted to some breeding individuals (I. Ramírez pers.comm.). Monitoring of the species is carried out by staff from the Madeiran Natural Park and other researchers, although such work requires great efforts, as the southern plateau of Bugio is extremely remote (I. Ramirez in litt. 2014).

Conservation Actions Proposed

Conduct coordinated surveys to obtain an up-to-date estimate for the total breeding population. Continue annual surveys to monitor population trends, adult survival and breeding success. Increase efforts to monitor soil erosion and continue to build/replace artificial nests. Refine the characterisation of the at-sea distribution of the species, using high-resolution tracking devices. Continue monitoring measures against rabbits and mice. Assess the impact of Larus michahellis through detailed research. 


Identification

35 cm. Medium-sized grey and white gadfly petrel. Grey upperparts with dark cap and dark M across wings. White underparts with indistinct pale grey half collar across upper breast. Predominantly dark grey-brown underwing. Similar spp. Zino's Petrel P. madeira is virtually identical but has a narrower, shorter bill and shorter wings. P. feae appears identical, though there are subtle vocal differences. Voice. On breeding grounds a range of wailing, cackling, ululating and hiccuping calls. Silent at sea.

Acknowledgements

Text account compilers
O'Brien, A., Peet, N., Shutes, S., Stuart, A., Symes, A., Taylor, J., Capper, D., Derhé, M., Anderson, O., Ashpole, J, Fjagesund, T., Hermes, C., Martin, R., Moreno, R.

Contributors
Bourne, W., Paiva, V., Geraldes, P., Zino, F., Gangloff, B., Ramirez, I., Menezes, D., Sultana, J., Oliveira, P.


Recommended citation
BirdLife International (2022) Species factsheet: Pterodroma deserta. Downloaded from http://www.birdlife.org on 26/11/2022. Recommended citation for factsheets for more than one species: BirdLife International (2022) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 26/11/2022.