Larus audouinii

Taxonomy

Assessment Information

Geographic Range

Population

Habitat and Ecology

Threats

Conservation Actions

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Taxonomy [top]

Kingdom	Phylum	Class	Order	Family
ANIMALIA	CHORDATA	AVES	CHARADRIIFORMES	LARIDAE

Scientific Name:

Larus audouinii

Species Authority:

Payraudeau, 1826

Common Name/s:

English	–	Audouin's Gull
French	–	Goéland d'Audouin

Assessment Information [top]

Red List Category & Criteria:

Near Threatened ver 3.1

Year Published:

2012

Assessor/s:

BirdLife International

Reviewer/s:

Butchart, S. & Symes, A.

Contributor/s:

Anderson, O., Arcos, J., Baccetti, N., Carboneras, C., Eken, G., Omnus, O., Oro, D., Papaconstantinou, C. & Portolou, D.

Justification:
This species may undergo a moderately rapid population decline in future if current fishery practices change and as such it is precautionarily treated as Near Threatened.

History:

2010	–	Near Threatened
2008	–	Near Threatened
2006	–	Near Threatened
2004	–	Near Threatened

Geographic Range [top]

Range Description:	Larus audouinii breeds in (all data for pairs) Spain (19,517 [Gutiérrez and Guinart 2008]), mainly the Chafarinas Islands and the Ebro Delta with the latter holding 67% of the global population (14,177 in 2007 [Gutiérrez and Guinart 2008]), Algeria (100-600), Greece (300-500 (D. Portolou in litt. 2010), and Sardinia and Tuscan Archipelago, Italy (1,019 [N. Baccetti in litt. 2008]), with smaller colonies in Portugal (11 [Gutiérrez and Guinart 2008]), Corsica, France (84 in 2009 [Recorbet and Culioli 2009]), Cyprus (c. 32 [Charalambidou and Gücel 2008]), islets and rocks in the southern Adriatic Sea near Korcula and Peljesac Peninsula, Croatia (65 in 5 colonies [Rubinic and Vrezec 2000]), Turkey (60-90 [G. Eken in litt. 1999]), Tunisia (70-115) and Morocco (50-300). It winters on the coast of North and West Africa from Libya west to Morocco and south to Mauritania, Gambia, Senegal and Gabon (Sanpera et al. 2007) and there is a small wintering population in the east Mediterranean along the Aegean coast of Turkey. The global population has been estimated at 21,161 pairs (Gutiérrez and Guinart 2008), and a recent assessment estimated the European population (encompassing over 90% of the global population) to be stable or increasing throughout (Barov and Derhé 2011). This represents a significant increase from an estimated population of 1,000 pairs in 1975 and is thought to be a result of the increased availability mainly of effectively protected areas during the 1980s, and secondly of discarded fish from the trawlers, particularly around the Ebro Delta (Criado 1997) where the colony has grown rapidly since 1981 (Guitiérrez and Guinart 2008). The large expansion of Larus audouinii in the western Mediterranean has probably caused the breeding population in other parts of the Mediterranean to increase and new colonies have been found in Croatia and even out of the Mediterranean in southern Portugal (BirdLife International 2004; Onmus 2006). Nevertheless more than 90% of the European breeding population occurs at just four sites and only a single site (the Ebro Delta) held 67% of the global breeding numbers in 2007. Recruitment can be extremely rapid when food availability is high, resulting in high population growth rates (Tavecchia et al. 2007; Oro and Pradel 2000). It is a long-lived species with high adult survival and relatively low fertility. Adult annual survival is estimated at 0.95 (Tavecchia et al. 2007; Oro et al. 1999, 2004).
Countries:	Native: Algeria; Croatia; Cyprus; France; Gambia; Gibraltar; Greece; Italy; Libya; Mauritania; Morocco; Portugal; Senegal; Spain; Tunisia; Turkey Vagrant: Bulgaria; Czech Republic; Egypt; Georgia; Germany; Israel; Jordan; Lebanon; Macedonia, the former Yugoslav Republic of; Malta; Palestinian Territory, Occupied; Switzerland; United Kingdom Present - origin uncertain: Albania; Bosnia and Herzegovina; Monaco; Montenegro; Slovenia; Syrian Arab Republic; Western Sahara
Range Map:	Click here to open the map viewer and explore range.

Population [top]

Population:	Gutiérrez and Guinart (2008) reported a global population of 21,161 pairs. However, more recent figures point to a total of 21,300-22,300 pairs, of which 21,080-21,310 pairs are in Europe. The global population is therefore estimated to number 63,900-66,900 individuals (G. Eken in litt. 1999, N. Baccetti in litt. 2008, D. Portolou in litt. 2010).
Population Trend:	Stable

Habitat and Ecology [top]

Habitat and Ecology:	Behaviour Audouin's Gull is a medium sized gull largely restricted to the Mediterranean. It is partially migratory and dispersive (del Hoyo et al. 1996). It breeds in large monospecific colonies ranging from 10 up to 10,000 pairs (del Hoyo et al. 1996) at a density of up to 1 nest/ sq. m (del Hoyo et al. 1996). Egg-laying takes place in the second half of April until the beginning of May, and peak hatching occurs in late May (del Hoyo et al. 1996), with fledging mainly in the first two weeks of July. It has a large foraging range while breeding, and has been recorded up to 200 km from the colony (Mañosa et al. 2004). After breeding the birds disperse widely around the Mediterranean coast (Sanpera et al. 2007; del Hoyo et al. 1996). Almost all juveniles and some adults migrate past Gibraltar during July-October (Olsen and Larsson 2003), peaking in August (Guitiérrez and Guinart 2008), to winter on the North African coast (del Hoyo et al. 1996). During the winter it roosts in flocks of several thousand (Olsen and Larsson 2003). It returns to its breeding sites between late February and mid April (del Hoyo et al. 1996). First year birds remain in the non-breeding range throughout the summer (Cramp and Simmons 1983), while most third-summer birds attend the breeding colony as non-breeders (Gutiérrez and Guinart 2008). Second-summer birds migrate to the Mediterranean but do not join the colony, instead forming large gatherings, often far from colonies (Gutiérrez and Guinart 2008). Very high colony-site fidelity is probably related to previous breeding success. However, in the Aegean Islands, birds return to the same "island group" but not necessarily to the same islet. At the Ebro Delta, Spain, c.1,400 breeders disperse to other colonies every year, generating marked fluctuations at those sites (Tavecchia et al. 2007). The Audouin's Gull is one of the few species of Larid to show nocturnal foraging patterns, which may be linked to fisheries activities; arrivals and departures from the Ebro Delta colony are in accordance with the trawling timetable (Mañosa et al. 2004). The species scavenges around fishing vessels, and uses discards extensively and very efficiently (Mañosa et al. 2004). The species's association with fisheries is more pronounced in the western than in the central and eastern Mediterranean (Pedrocchi et al.2002). A trawler moratorium off the Ebro Delta established in 1991 reduced food availability to birds and impacted breeding success, possibly by increasing foraging ranges (Arcos and Oro 1996). Habitat Breeding Colonies are located on exposed rocky cliffs and on offshore islands or islets (Cramp and Simmons 1983), normally not more than 50 m above sea level (Cramp and Simmons 1983). The Ebro delta colony is located on saltmarsh and a sandy peninsula (Olsen and Larsson 2003). In the Aegean it breeds on uninhabited islands sloping gently to the sea and covered with large stones, eryngo Eryngium, grass and low bushes of Pistacia lentiscus (Cramp and Simmons 1983). Characteristics of habitats used differ from region to region and even within the same areas in different years: altitude ranges from close to sea-level to 100 m, vegetation cover from bare rocks to 85% bush cover, and slope from 0-90^o. Medium vegetation cover is preferred, and this probably provides chicks with shelter from heat and predators. The concentration of breeding colonies in the western Mediterranean is possibly related to the lower water salinity and higher abundance of clupeids. Non-breeding During the non-breeding season the species prefers sheltered bays, either flat and shingly, sandy or with cliffed margins (Cramp and Simmons 1983). It sometimes visits seaside resorts and marinas lured by food, and it especially likes areas on beaches where freshwater occurs, such as stream mouths or floods (Cramp and Simmons 1983). It is a coastal species, rarely occurring inland and generally not travelling far offshore (Cramp and Simmons 1983). Diet This species was historically thought to feed far out to sea, but more recent observations show that it feeds regularly along the coast. The diet consists mostly of epipelagic fish, especially Clupeiformes, for which it sometimes forages at night, taking advantage of its prey's diel migration patterns (Mañosa et al. 2004) and of commercial fishing by purse-seine netting (Pedrocchi et al.2002). It is also known to take some aquatic and terrestrial invertebrates, small birds and plant material such as the peanut Arachis, olive Olea, and grain (Cramp and Simmons 1983). The Ebro delta colony feeds largely on fish waste dumped by boats fishing nearby (Oro and Martínez-Vilalta 1992). The species is also known to feed on food discarded at tourist beaches (Cramp and Simmons 1983), and during a moratorium on trawling, it was found to forage in marshes, rice fields and occasionally at refuse tips (Mañosa et al. 2004; del Hoyo et al. 1996). They began to exploit the introduced North American Red Swamp Crayfish Procambarus clarkia, which are abundant in rice fields around the delta (Gutiérrez and Guinart 2008). Hence Ebro Delta birds have developed from being mainly pelagic foragers to more coastal-foraging, even scavenging species (Gutiérrez and Guinart 2008). The fishing mortatorium was relaxed in 2000 during the birds breeding season, and as discards became available, so the population was boosted once again (Gutiérrez and Guinart 2008). Diet during the breeding season has been found to vary between colonies due to fishing practices that target different species in the respective areas (Pedrocchi et al.2002). Breeding site The nests is a shallow scrape lined with available debris and vegetation (Cramp and Simmons 1983). It is placed among rocks and vegetation (del Hoyo et al. 1996). Foraging range During the non-breeding season, surveys in Morocco found birds no further than 46 km from the coast (Hoogendoorn and Mackrill 1987), and generally <40 km from the colony seems to be the norm (Mañosa et al. 2004). However, the maximum recorded foraging range from a colony was 160 km (Mañosa et al. 2004). In recent years, some birds have remained at the Ebro Delta colony over-winter, with an average of c. 90 birds during 1996-2008, but occasionally up to 300 birds (Gutiérrez and Guinart 2008). The species primarily forages in coastal and continental shelf areas between 5 and 15 nautical miles (nm) offshore. A radius of 15 nm from the Ebro Delta would ensure the protection of 30% of the birds (or 30% of the foraging area). A 30 nm radius would protect 80% of birds. These distances could be reduced in colonies where the surrounding continental shelf is narrower (SEO/BirdLife in litt. 2010). Juveniles tend to forage in upwelling zones, whereas subadults and adults are more independent of these sites (Martinez-Abrain et al 2002). It remains extremely rare along the northern coast of Spain (Gutiérrez and Guinart 2008).
Systems:	Terrestrial; Marine

Habitat and Ecology:

Behaviour Audouin's Gull is a medium sized gull largely restricted to the Mediterranean. It is partially migratory and dispersive (del Hoyo et al. 1996). It breeds in large monospecific colonies ranging from 10 up to 10,000 pairs (del Hoyo et al. 1996) at a density of up to 1 nest/ sq. m (del Hoyo et al. 1996). Egg-laying takes place in the second half of April until the beginning of May, and peak hatching occurs in late May (del Hoyo et al. 1996), with fledging mainly in the first two weeks of July. It has a large foraging range while breeding, and has been recorded up to 200 km from the colony (Mañosa et al. 2004). After breeding the birds disperse widely around the Mediterranean coast (Sanpera et al. 2007; del Hoyo et al. 1996). Almost all juveniles and some adults migrate past Gibraltar during July-October (Olsen and Larsson 2003), peaking in August (Guitiérrez and Guinart 2008), to winter on the North African coast (del Hoyo et al. 1996). During the winter it roosts in flocks of several thousand (Olsen and Larsson 2003). It returns to its breeding sites between late February and mid April (del Hoyo et al. 1996). First year birds remain in the non-breeding range throughout the summer (Cramp and Simmons 1983), while most third-summer birds attend the breeding colony as non-breeders (Gutiérrez and Guinart 2008). Second-summer birds migrate to the Mediterranean but do not join the colony, instead forming large gatherings, often far from colonies (Gutiérrez and Guinart 2008). Very high colony-site fidelity is probably related to previous breeding success. However, in the Aegean Islands, birds return to the same "island group" but not necessarily to the same islet. At the Ebro Delta, Spain, c.1,400 breeders disperse to other colonies every year, generating marked fluctuations at those sites (Tavecchia et al. 2007). The Audouin's Gull is one of the few species of Larid to show nocturnal foraging patterns, which may be linked to fisheries activities; arrivals and departures from the Ebro Delta colony are in accordance with the trawling timetable (Mañosa et al. 2004). The species scavenges around fishing vessels, and uses discards extensively and very efficiently (Mañosa et al. 2004). The species's association with fisheries is more pronounced in the western than in the central and eastern Mediterranean (Pedrocchi et al.2002). A trawler moratorium off the Ebro Delta established in 1991 reduced food availability to birds and impacted breeding success, possibly by increasing foraging ranges (Arcos and Oro 1996). Habitat Breeding Colonies are located on exposed rocky cliffs and on offshore islands or islets (Cramp and Simmons 1983), normally not more than 50 m above sea level (Cramp and Simmons 1983). The Ebro delta colony is located on saltmarsh and a sandy peninsula (Olsen and Larsson 2003). In the Aegean it breeds on uninhabited islands sloping gently to the sea and covered with large stones, eryngo Eryngium, grass and low bushes of Pistacia lentiscus (Cramp and Simmons 1983). Characteristics of habitats used differ from region to region and even within the same areas in different years: altitude ranges from close to sea-level to 100 m, vegetation cover from bare rocks to 85% bush cover, and slope from 0-90^o. Medium vegetation cover is preferred, and this probably provides chicks with shelter from heat and predators. The concentration of breeding colonies in the western Mediterranean is possibly related to the lower water salinity and higher abundance of clupeids. Non-breeding During the non-breeding season the species prefers sheltered bays, either flat and shingly, sandy or with cliffed margins (Cramp and Simmons 1983). It sometimes visits seaside resorts and marinas lured by food, and it especially likes areas on beaches where freshwater occurs, such as stream mouths or floods (Cramp and Simmons 1983). It is a coastal species, rarely occurring inland and generally not travelling far offshore (Cramp and Simmons 1983). Diet This species was historically thought to feed far out to sea, but more recent observations show that it feeds regularly along the coast. The diet consists mostly of epipelagic fish, especially Clupeiformes, for which it sometimes forages at night, taking advantage of its prey's diel migration patterns (Mañosa et al. 2004) and of commercial fishing by purse-seine netting (Pedrocchi et al.2002). It is also known to take some aquatic and terrestrial invertebrates, small birds and plant material such as the peanut Arachis, olive Olea, and grain (Cramp and Simmons 1983). The Ebro delta colony feeds largely on fish waste dumped by boats fishing nearby (Oro and Martínez-Vilalta 1992). The species is also known to feed on food discarded at tourist beaches (Cramp and Simmons 1983), and during a moratorium on trawling, it was found to forage in marshes, rice fields and occasionally at refuse tips (Mañosa et al. 2004; del Hoyo et al. 1996). They began to exploit the introduced North American Red Swamp Crayfish Procambarus clarkia, which are abundant in rice fields around the delta (Gutiérrez and Guinart 2008). Hence Ebro Delta birds have developed from being mainly pelagic foragers to more coastal-foraging, even scavenging species (Gutiérrez and Guinart 2008). The fishing mortatorium was relaxed in 2000 during the birds breeding season, and as discards became available, so the population was boosted once again (Gutiérrez and Guinart 2008). Diet during the breeding season has been found to vary between colonies due to fishing practices that target different species in the respective areas (Pedrocchi et al.2002). Breeding site The nests is a shallow scrape lined with available debris and vegetation (Cramp and Simmons 1983). It is placed among rocks and vegetation (del Hoyo et al. 1996). Foraging range During the non-breeding season, surveys in Morocco found birds no further than 46 km from the coast (Hoogendoorn and Mackrill 1987), and generally <40 km from the colony seems to be the norm (Mañosa et al. 2004). However, the maximum recorded foraging range from a colony was 160 km (Mañosa et al. 2004). In recent years, some birds have remained at the Ebro Delta colony over-winter, with an average of c. 90 birds during 1996-2008, but occasionally up to 300 birds (Gutiérrez and Guinart 2008). The species primarily forages in coastal and continental shelf areas between 5 and 15 nautical miles (nm) offshore. A radius of 15 nm from the Ebro Delta would ensure the protection of 30% of the birds (or 30% of the foraging area). A 30 nm radius would protect 80% of birds. These distances could be reduced in colonies where the surrounding continental shelf is narrower (SEO/BirdLife in litt. 2010). Juveniles tend to forage in upwelling zones, whereas subadults and adults are more independent of these sites (Martinez-Abrain et al 2002). It remains extremely rare along the northern coast of Spain (Gutiérrez and Guinart 2008).

Systems:

Terrestrial; Marine

Threats [top]

Major Threat(s):	The trawling fishery off the Ebro Delta is regarded as unsustainable and its collapse would probably result in a decline in the breeding population due to the increase in density-dependence (Oro et al. 2004, Tavecchia et al. 2007, Barov and Derhé 2011). A similar outcome would arise if waste from the trawlers were used industrially to produce food for domestic animals, as occurs in other areas, rather than being dumped near the Ebro colony. More important could be the reduction of small-pelagic fish stocks, the main natural prey for Audouin's Gull, due to increasingly high fishing pressure around the breeding grounds, owing partly to high demand by tuna-farming (Arcos et al. 2006). Other important threats include coastal tourism developments, regulation of the river Ebro, mortality due to entanglement in fishing gear (mainly longlines and sporting lines) (Cooper et al. 2003; Belda and Sánchez 2000), and predation by terrestrial predators, such as red fox Vulpes vulpes, badger Meles meles and domestic dogs (Tavecchia et al. 2007; Oro et al. 1999). Predation by sympatric Yellow-legged Gull L. michahellis can be high at some breeding colonies, especially when densities of Audouin's Gulls are low (Bonaccorsi 2003; Travichon 2004; Oro et al. 2006; Paracuellos and Nevado 2010). Predation on chicks by black rats Rattus rattus has a negative impact at some breeding colonies (Jones et al. 2008). Nevertheless Audouin's Gull shows a very nomadic breeding site selection and high dispersal rates from year to year, probably avoiding large densities of Yellow-legged Gulls (Oro and Matínez-Abraín 2007; Genovart et al. 2003; Martínez-Abraín et al. 2003). Peregrines Falco peregrinus, other raptors, some herons and snakes can also prey on adults and nests but only accidentally and locally (Oro 1997, 1996). Very high levels of mercury and other pollutants are found in this species (Sanpera et al. 2007), partly due to the consumption of discards (Arcos et al. 2002), thus posing a potential threat, although no negative effects have been demonstrated. Current marine wind-farm projects, particularly around the main breeding colony (Ebro Delta), could also represent a serious threat. Overgrazing of some islets by goats in the east of its breeding range may reduce breeding success. Natal and breeding dispersal are extremely high ensuring genetic mixing and buffering against bad local environmental conditions through emigration and colonisation (Oro and Ruxton 2001; Oro et al. 2004).

Major Threat(s):

The trawling fishery off the Ebro Delta is regarded as unsustainable and its collapse would probably result in a decline in the breeding population due to the increase in density-dependence (Oro et al. 2004, Tavecchia et al. 2007, Barov and Derhé 2011). A similar outcome would arise if waste from the trawlers were used industrially to produce food for domestic animals, as occurs in other areas, rather than being dumped near the Ebro colony. More important could be the reduction of small-pelagic fish stocks, the main natural prey for Audouin's Gull, due to increasingly high fishing pressure around the breeding grounds, owing partly to high demand by tuna-farming (Arcos et al. 2006). Other important threats include coastal tourism developments, regulation of the river Ebro, mortality due to entanglement in fishing gear (mainly longlines and sporting lines) (Cooper et al. 2003; Belda and Sánchez 2000), and predation by terrestrial predators, such as red fox Vulpes vulpes, badger Meles meles and domestic dogs (Tavecchia et al. 2007; Oro et al. 1999). Predation by sympatric Yellow-legged Gull L. michahellis can be high at some breeding colonies, especially when densities of Audouin's Gulls are low (Bonaccorsi 2003; Travichon 2004; Oro et al. 2006; Paracuellos and Nevado 2010). Predation on chicks by black rats Rattus rattus has a negative impact at some breeding colonies (Jones et al. 2008). Nevertheless Audouin's Gull shows a very nomadic breeding site selection and high dispersal rates from year to year, probably avoiding large densities of Yellow-legged Gulls (Oro and Matínez-Abraín 2007; Genovart et al. 2003; Martínez-Abraín et al. 2003). Peregrines Falco peregrinus, other raptors, some herons and snakes can also prey on adults and nests but only accidentally and locally (Oro 1997, 1996). Very high levels of mercury and other pollutants are found in this species (Sanpera et al. 2007), partly due to the consumption of discards (Arcos et al. 2002), thus posing a potential threat, although no negative effects have been demonstrated. Current marine wind-farm projects, particularly around the main breeding colony (Ebro Delta), could also represent a serious threat. Overgrazing of some islets by goats in the east of its breeding range may reduce breeding success. Natal and breeding dispersal are extremely high ensuring genetic mixing and buffering against bad local environmental conditions through emigration and colonisation (Oro and Ruxton 2001; Oro et al. 2004).

Conservation Actions [top]

Conservation Actions:	Conservation Actions Underway CMS Appendix I and II. A European action plan was published in 1996. The ecology of this species, particularly its breeding and foraging behaviour and demography and population dynamics, has been extensively studied. Lebanon prepared an action plan to restore the breeding population back to Palm Islands Nature reserve. Several LIFE Nature projects have been implemented between 1992 and 2006 in Spain and Italy, contributing to successful recolonisation of breeding islands and development of safe line-fishing techniques. Control of invasive black rats Rattus rattus has been effective at some colonies (Jones et al. 2008). Culling of Yellow-legged Gulls Larus michehellis was conducted from 2000 to 2009 on Alborán Island, Spain, and demonstrated immediate local benefits (Paracuellos and Nevado 2010). However, even in small, remote colonies, culling needs to be continuous to avoid a return to the original situation (Paracuellos and Nevado 2010). Conservation Actions Proposed Continue to monitor breeding colonies. Identify appropriate actions to mitigate against the key threats. Implement strict fishery management policies in the species's range. Increase the area of suitable coastal habitat that is protected from development and degradation. Enforce laws designed to minimise marine pollution. Implement measures to reduce mortality in fishing gear, perhaps facilitated by legislation. Ensure regulation of the river Ebro benefits the species.

Conservation Actions:

Conservation Actions Underway
CMS Appendix I and II. A European action plan was published in 1996. The ecology of this species, particularly its breeding and foraging behaviour and demography and population dynamics, has been extensively studied. Lebanon prepared an action plan to restore the breeding population back to Palm Islands Nature reserve. Several LIFE Nature projects have been implemented between 1992 and 2006 in Spain and Italy, contributing to successful recolonisation of breeding islands and development of safe line-fishing techniques. Control of invasive black rats Rattus rattus has been effective at some colonies (Jones et al. 2008). Culling of Yellow-legged Gulls Larus michehellis was conducted from 2000 to 2009 on Alborán Island, Spain, and demonstrated immediate local benefits (Paracuellos and Nevado 2010). However, even in small, remote colonies, culling needs to be continuous to avoid a return to the original situation (Paracuellos and Nevado 2010).

Conservation Actions Proposed
Continue to monitor breeding colonies. Identify appropriate actions to mitigate against the key threats. Implement strict fishery management policies in the species's range. Increase the area of suitable coastal habitat that is protected from development and degradation. Enforce laws designed to minimise marine pollution. Implement measures to reduce mortality in fishing gear, perhaps facilitated by legislation. Ensure regulation of the river Ebro benefits the species.

Citation:	BirdLife International 2012. Larus audouinii. In: IUCN 2012. IUCN Red List of Threatened Species. Version 2012.2. <www.iucnredlist.org>. Downloaded on 24 May 2013.
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