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 Assessed:

2010

Assessor/s:

BirdLife International

Reviewer/s:

Calvert, R., Butchart, S., Bird, J.

Contributor/s:

Oro, D., Eken, G., Omnus, O., Arcos, J., Papaconstantinou, C., Carboneras, C.

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:

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

Geographic Range [top]

Range Description:	Larus audouinii breeds in (all data for pairs) Spain (20,315⁴), mainly the Chafarinas Islands and the Ebro Delta with the latter holding 65% of the global population⁹, Algeria (100-600), Greece (700-900³ in 65 colonies), and the Sardinia and Tuscan Archipelago, Italy (550-650), with smaller colonies in Portugal (40), Corsica, France (between 54-60⁵and 80⁷), Cyprus (c. 32⁴⁰), islets and rocks in the southern Adriatic Sea near Korcula and Peljesac Peninsula, Croatia (65⁸ in 5 colonies), Turkey (60-90²), 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 Gabon¹³ and there is a small wintering population in the east Mediterranean along the Aegean coast of Turkey. The global population has been estimated at c.21,500 pairs, and a recent assessment put the European population (including some Spanish islands and islets off Morocco) at 20,500-21,000 pairs (encompassing over 90% of the global population) and stable or increasing throughout. 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 Delta¹. 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^10,12. Nevertheless more than 90% of the European breeding population occurs at just four sitesand only a single site (the Ebro Delta) held 70% of the global breeding numbers in 2006. Recruitment can be extremely rapid when food availability is high, resulting in high population growth rates^15,26. It is a long-lived species with high adult survival and relatively low fertility. Adult annual survival is estimated at 0.95^15,19,25.
Countries:	Native: Algeria; Croatia; Cyprus; France; Gambia; Gibraltar; Greece; Italy; Libyan Arab Jamahiriya; 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:	The global population (excluding Europe) is estimated to be 19,200 pairs (Lambertini 1996), with 18,000-19,000 pairs in Europe (BirdLife International 2004), giving a total of 57,600 individuals.
Population Trend:	Decreasing

Population:

The global population (excluding Europe) is estimated to be 19,200 pairs (Lambertini 1996), with 18,000-19,000 pairs in Europe (BirdLife International 2004), giving a total of 57,600 individuals.

Population Trend:

Decreasing

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 dispersive³⁰. It breeds in large monospecific colonies ranging from 10 up to 10,000 pairs³⁰ at a density of up to 1 nest/ sq. m³⁰. Egg-laying takes place in the second half of April until the beginning of May, and peak hatching occurs in late May³⁰, 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 colony²⁷. After breeding the birds disperse widely around the Mediterranean coast^13,30. Almost all juveniles and some adults migrate past Gibraltar during July-October³¹, to winter on the North African coast³⁰. During the winter it roosts in flocks of several thousand³¹. It returns to its breeding sites between late February and mid April³⁰. First year birds remain in the non-breeding range throughout the summer³². 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 sites¹⁵. 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 timetable²⁷. The species scavenges around fishing vessels, and uses discards extensively and very efficiently²⁷. The species's association with fisheries is more pronounced in the western than in the central and eastern Mediterranean³⁴. A trawler moratorium off the Ebro Delta has caused decreased food availability to birds and has also negatively affected breeding success, possibly by necessitating increased foraging ranges³⁶. Habitat Breeding Colonies are located on exposed rocky cliffs and on offshore islands or islets³², normally not more than 50 m above sea level³². The Ebro delta colony is located on saltmarsh and a sandy peninsula³¹. 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 lentiscus³². 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 margins³². 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 floods³². It is a coastal species, rarely occurring inland and generally not travelling far offshore³². 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 patterns²⁷ and of commercial fishing by purse-seine netting³⁴. It is also known to take some aquatic and terrestrial invertebrates, small birds and plant material such as the peanut Arachis, olive Olea, and grain³². The Ebro delta colony feeds largely on fish waste dumped by boats fishing nearby³³. The species is also known to feed on food discarded at tourist beaches³², and during a moratorium on trawling, it was found to forage in marshes, rice fields and occasionally at refuse tips^27,30. Diet during the breeding season has been found to vary between colonies due to fishing practices that target different species in the respective areas³⁴. Breeding site The nests is a shallow scrape lined with available debris and vegetation³². It is placed among rocks and vegetation³⁰. Foraging range During the non-breeding season, surveys in Morocco found birds no further than 46 km from the coast³⁷, and generally <40 km from the colony seems to be the norm²⁷. However, the maximum recorded foraging range from a colony was 160 km²⁷. 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 narrower³⁸. Juveniles tend to forage in upwelling zones, whereas subadults and adults are more independent of these sites³⁹.
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 dispersive³⁰. It breeds in large monospecific colonies ranging from 10 up to 10,000 pairs³⁰ at a density of up to 1 nest/ sq. m³⁰. Egg-laying takes place in the second half of April until the beginning of May, and peak hatching occurs in late May³⁰, 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 colony²⁷. After breeding the birds disperse widely around the Mediterranean coast^13,30. Almost all juveniles and some adults migrate past Gibraltar during July-October³¹, to winter on the North African coast³⁰. During the winter it roosts in flocks of several thousand³¹. It returns to its breeding sites between late February and mid April³⁰. First year birds remain in the non-breeding range throughout the summer³². 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 sites¹⁵. 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 timetable²⁷. The species scavenges around fishing vessels, and uses discards extensively and very efficiently²⁷. The species's association with fisheries is more pronounced in the western than in the central and eastern Mediterranean³⁴. A trawler moratorium off the Ebro Delta has caused decreased food availability to birds and has also negatively affected breeding success, possibly by necessitating increased foraging ranges³⁶. Habitat Breeding Colonies are located on exposed rocky cliffs and on offshore islands or islets³², normally not more than 50 m above sea level³². The Ebro delta colony is located on saltmarsh and a sandy peninsula³¹. 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 lentiscus³². 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 margins³². 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 floods³². It is a coastal species, rarely occurring inland and generally not travelling far offshore³². 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 patterns²⁷ and of commercial fishing by purse-seine netting³⁴. It is also known to take some aquatic and terrestrial invertebrates, small birds and plant material such as the peanut Arachis, olive Olea, and grain³². The Ebro delta colony feeds largely on fish waste dumped by boats fishing nearby³³. The species is also known to feed on food discarded at tourist beaches³², and during a moratorium on trawling, it was found to forage in marshes, rice fields and occasionally at refuse tips^27,30. Diet during the breeding season has been found to vary between colonies due to fishing practices that target different species in the respective areas³⁴. Breeding site The nests is a shallow scrape lined with available debris and vegetation³². It is placed among rocks and vegetation³⁰. Foraging range During the non-breeding season, surveys in Morocco found birds no further than 46 km from the coast³⁷, and generally <40 km from the colony seems to be the norm²⁷. However, the maximum recorded foraging range from a colony was 160 km²⁷. 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 narrower³⁸. Juveniles tend to forage in upwelling zones, whereas subadults and adults are more independent of these sites³⁹.

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^15,25. 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-farming²⁸. Other important threats include coastal tourism developments, regulation of the river Ebro, mortality due to entanglement in fishing gear (mainly longlines and sporting lines)^17,18, and predation by terrestrial predators, such as red fox Vulpes vulpes, badger Meles meles and domestic dogs^15,19. Predation by sympatric Yellow-legged Gull L. michahellis can be high at some breeding colonies, especially when densities of Audouin's Gulls are low^6,11,16. Predation on chicks by black rats Rattus rattus has a negative impact at some breeding colonies³⁵. 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^20,21,22. Peregrines Falco peregrinus, other raptors, some herons and snakes can also prey on adults and nests but only accidentally and locally^23,24. Very high levels of mercury and other pollutants are found in this species¹³, partly due to the consumption of discards²⁹, 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^9,25.

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^15,25. 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-farming²⁸. Other important threats include coastal tourism developments, regulation of the river Ebro, mortality due to entanglement in fishing gear (mainly longlines and sporting lines)^17,18, and predation by terrestrial predators, such as red fox Vulpes vulpes, badger Meles meles and domestic dogs^15,19. Predation by sympatric Yellow-legged Gull L. michahellis can be high at some breeding colonies, especially when densities of Audouin's Gulls are low^6,11,16. Predation on chicks by black rats Rattus rattus has a negative impact at some breeding colonies³⁵. 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^20,21,22. Peregrines Falco peregrinus, other raptors, some herons and snakes can also prey on adults and nests but only accidentally and locally^23,24. Very high levels of mercury and other pollutants are found in this species¹³, partly due to the consumption of discards²⁹, 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^9,25.

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 colonies³⁵. 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 colonies³⁵.

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 2010. Larus audouinii. In: IUCN 2011. IUCN Red List of Threatened Species. Version 2011.2. <www.iucnredlist.org>. Downloaded on 09 February 2012.
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