Summary of Knowledge on the Status of Waders And

Home , East Atlantic Flyway

SUMMARY OF KNOWLEDGE ON THE STATUS OF WADERS AND COASTAL SEABIRDS ON KEY NATURAL SITES OF THE WEST AFRICA’S COASTLINE Knowledge synthesis written by Pierre Campredon Within the framework of the MAVA Action Plan for the conservation of wetlands and coastal birds in West Africa

ABSTRACT...... 4

INTRODUCTION...... 6

INFORMATION AND DATA SOURCES...... 8

CENSUS MODALITIES AND SCOPE...... 10

RELEVANT BIRD POPULATIONS...... 12

Waders ...... 12

Coastal seabirds...... 16

STATUS OF COASTAL WATERBIRDS ON KEY SITES...... 18

Banc d’Arguin National Park ...... 18

Senegal River lower delta...... 22

Saloum Delta National Park (PNDS)...... 25

The Bijagós Archipelago...... 28

CONCLUSION...... 34

BIBLIOGRAPHY...... 38

The status of waders and coastal seabirds on key natural sites of the West Africa’s coastline ABSTRACT

A review of the status of coastal waterbirds º 6 to 8 months per year, West Africa’s on key sites of the West Africa’s coastline sites are home to a significant number was undertaken as part of the Plan of of small or migratory waders that breed action for the conservation of wetlands and from Northern Europe to the Canadian coastal birds (PAZHOC). The conclusions Arctic through Siberia, and belong to below were arrived at after examining, the East-Atlantic Flyway. in the light of international bird counts º Populations of these waders have been and scientific publications, the reports globally declining since 1980s-1990s. on priority sites, i.e. the Banc d’Arguin National Park (PNBA) and the Diawling º The causes of this decline are difficult National Park in Mauritania, the Langue to establish or prioritise, owing to the de Barbarie National Park and the Saloum fact these populations live in different Delta National Park (PNSD) in Senegal, and environments throughout the year. the Bijagós Archipelago Biosphere Reserve The two African sites hosting the big in Guinea-Bissau: majority of their individuals, i.e. the Banc

The status of waders and coastal seabirds on key natural sites of the West Africa’s coastline Abstract 5

d’Arguin and the Bijagós Archipelago, The overall status of coastal seabird species do not seem to have undergone covered by the Plan of action looks good, at changes that alone could explain such least for Caspian and Royal Terns as well as a decline. Although a few changes did Slender-billed Gulls whose populations are occur, including the evolving pressure considered to be either stable or growing. exerted by fisheries, it should be noted, Although improvements have been made however, that water birds feeding on to count techniques, especially through the fishes have been less affected than introduction of drones, these results need those feeding on invertebrates living in to be considered with precaution, owing the mud. to the threats facing colonial birds in the more or less long term. Indeed, on all sites, º The causes of the decline may lie observers have noted the erosion of sandy in the migratory process, when islets, which provide a nesting habitat weather conditions are not conducive, for those species, and frequent episodes compelling birds to change their of clutch submersion, which has to be itineraries and stopover sites. They may correlated with sea level rise. Other threats also be found on the stopover sites include nest predation, the disturbance which play a key role by enabling birds caused by tourism or the introduction to replenish their body reserves before of free-ranging pigs on the island where heading to their breeding grounds, often major colonies of terns are likely to find a located at more than 10,000 km from home in the Bijagós Archipelago. their wintering sites in Africa. It is a known fact that the Wadden Sea in the Waterbirds must not only be considered Netherlands is the key stopover site of for their intrinsic value as components these species, and that it has suffered of biodiversity. Their functions in the degradation due to mudflats being maintenance and balance of coastal mechanically dredged for the industrial ecosystems must also be recognised. exploitation of shells or sand extraction. Consideration must also be given to their role as indicators of changing º Finally, the causes may be linked environments. This is particularly true of to the very breeding grounds in waders which fly over large parts of the situations where weather conditions globe during their annual cycle through are unfavourable or when, for want of a variety of biomes and climate zones, lemmings (rodents) in great numbers, and can therefore serve as “integrative foxes or raptors hunt waders for food. sentinels” for the global changes that are º It is a fact that in the longer term, currently affecting our planet. climate changes will play a role in the In the face of the uncertainties about the evolution of wader species. On African future of coastal birds, there is a need sites, the rise in temperature could lead to step up efforts in terms of scientific to hyperthermia phenomena in birds research, technicians’ training and when during the moult. As for the rise institutional strengthening at the national in the sea level, it will impact the spatial level within the framework of partnerships and temporal accessibility of mudflats to be established on the scale of the flyway as a source of feeding for birds. as a whole, as is currently the case under the PAZHOC Plan.

The status of waders and coastal seabirds on key natural sites of the West Africa’s coastline INTRODUCTION

shorebirds, which are among the greatest The interface between sea and migratory birds in the world and have no land is where the world’s most other place to live. productive habitats are found The conservation of shorebirds and coastal seabirds as well as their habitats is of The interface between sea and land is particular importance, not only because where the world’s most productive habitats they represent a resource shared by several are found: shallow seas, intertidal mudflats, countries from the tropical latitudes to mangroves and coastal swamps. This is the Arctic Circle, but also because they where the bulk of human populations live, play an ecological role in the coastal where global industries are concentrated ecosystems that provide essential services and where food is produced on fertile soils. to human populations. For these reasons, This is also where the impact of sea level their conservation has been established rise and the fast-changing river flows is as a priority by national bodies dealing most felt. Present as well in this zone are with biodiversity and protected areas, in

The status of waders and coastal seabirds on key natural sites of the West Africa’s coastline introduction 7

partnership with regional and international count methods. Since it remains to be organisations involved in joint initiatives for established whether this is a structural the protection of their biodiversity under evolution or a temporal fluctuation, the PRCM and AEWA/CMS, among others. there is an urgent need for research and monitoring work to be done on the basis of concerted programmes, such as the Plan of Globally the size of the action on wetlands and coastal birds being implemented in West Africa by a range of populations of waterbirds national and international partners. concerned decreased by It was in this context that it was deemed appropriate to produce a document nearly 2.5 million individuals providing an overview of the status of between 2003 and 2014 the populations of waders and coastal seabirds on each of the key sites covered by the PAZHOC Plan. Summary papers In 2015, Wetlands International published were thus prepared for the Banc d’Arguin an alarming report on the status of National Park (Ba et al. 2018), the lower waterbirds of the East Atlantic Flyway. Delta of the Senegal River, including the The report reviewed the status of 66 bird Diawling National Park (Ba et al. 2018) and populations against data from international the Langue de Barbarie National Park (Diop counts covering several years (Wetlands et al. 2018), the Saloum Delta National International 2015, van Roomen et al. 2015). Park (Diop et al. 2018) and the Bijagós The key message from this report was Archipelago Biosphere Reserve (Henriques, that globally the size of the populations of 2019). By putting together such summary waterbirds concerned decreased by nearly papers and this regional consolidation 2.5 million individuals between 2003 and document, the objective was not only to 2014. The reasons for this decrease are develop baselines for emerging trends multifaceted and difficult to distinguish, but also collect useful information for the especially as these are highly mobile definition of waterbirds management and species successively living in various conservation priorities while providing environments throughout their annual elements that would feed into the cycle and that the data on their sizes were communication and advocacy strategies of collected through particularly complex the PRCM and its partners.

The status of waders and coastal seabirds on key natural sites of the West Africa’s coastline INFORMATION AND DATA SOURCES

Waterbird Census conducted out of the Field missions were undertaken breeding period, mainly in January (van by national institutions of the Roomen et al. 2014). Every year, counts are organised and coordinated by Wetlands respective countries, in most International (Delany et al. 1999, Dodman et al. 1999). Additional counting took place cases with the assistance in West Africa in 2014 in order to close a of international experts few gaps and allow for comparisons. These were made possible with the concerted The large majority of data concerning the efforts of the Wadden Sea Flyway Initiative population size of birds of the East Atlantic (WSFI) and the Conservation of Migratory Flyway are derived from the International Bird Project (CMB), under the coordination

The status of waders and coastal seabirds on key natural sites of the West Africa’s coastline Information and data sources 9

of BirdLife International in collaboration With regard to colonial seabirds, the with Wetlands International. Field missions information is derived from the counts of were undertaken by national institutions breeding colonies performed on a limited of the respective countries, in most number of known sites in West Africa. The cases with the assistance of international findings were later summarised by Veen et experts. Details about census data for al. (2007 and 2011) and Dodman (2014). Most each site as well as the institutions of the data on the numbers of breeding responsible at country level are available birds were obtained through the activities online at the following address : carried out by national institutions in http://www.wetlands.org charge of protected areas and biodiversity, in collaboration with international experts, including in the framework of the Alcyon Project coordinated by BirdLife Research work was International and financed by the MAVA Foundation. simultaneously conducted Research work was simultaneously with the support of a conducted with the support of a number of international teams, mainly from the number of international Netherlands (NIOZ, Groningen University, VEDA Consulting, to mention a few) and teams (...) in most cases more recently from Portugal (Lisbon in cooperation with and Aveiro Universities, ISPA Institute), and in most cases in cooperation with organisations involved in organisations involved in the management of the East Atlantic Flyway, such as BirdLife the management of the International, the Wadden Sea Flyway East Atlantic Flyway Initiative, the Conservation of Migratory Birds Project and the AEWA/CMS African Initiative.

The status of waders and coastal seabirds on key natural sites of the West Africa’s coastline CENSUS MODALITIES AND SCOPE

The count methods varied considerably simultaneous counting exercise throughout depending on whether the sites were the distribution range, as this is the used for migrating, overwintering1 or period of the year when bird populations breeding purposes by the populations are stable and concentrated on a limited concerned. Regarding wader population number of sites. on the sites covered by this summary The count methods involved a series of document, the census took place during difficulties, and therefore call for particular their overwintering period. The month of prudence in interpreting the findings (see January was found to be suitable for a the analysis of Oudman et al. 2017 made on account of the PNBA). It is known that The month of January was the counting of major groups of waders found to be suitable for a 1 By overwintering period, in reference to winter in temperate countries, is meant the period outside the simultaneous counting exercise breeding season and migratory phases.

The status of waders and coastal seabirds on key natural sites of the West Africa’s coastline Census modalities and scope 11

is not exempt from significant margins site. The technique of observing birds of error, even when this is performed by with coloured rings is also often used to experienced counters. Such an extreme estimate by deduction the size of bird case occurred at the Banc d’Arguin National populations (Oudman et al. 2017). Park where a single group of waders was Coastal seabird populations are generally estimated at 1.1 million individuals. Most counted during the breeding period. This of these populations are multi-species, is when they gather in colonies on a small which may lead to an underestimation of number of known sites, which makes less abundant, smaller and less visible the counting exercise easier. Particular species within bigger groups of species, precautionary measures are observed in in which case the quality of the counting the counting process to minimise risks of would largely depend on how experienced disturbance to ground-nesting colonies, the observer is. Failure to simultaneously which may cause adult individuals to flee, counting different areas used by the same high mortality among chicks or even egg birds may result in some groups being predation by other bird species (Veen et counted twice. This source of error is al. 2004). The counting is to be conducted frequent on largest and difficult to access outside of the hot hours and when chicks sites. Moreover, some species, including have reached a certain age. It is performed the Whimbrel, use closed environments by a team of observers who count nests as a rest place at high tide, especially in directly or measure the surface covered by mangrove areas where visibility is poor. the colony and then figure up the number of couples from the density of nests. Also Coastal seabird populations subject to observation are other breeding parameters such as the number of eggs are generally counted during per nest or the growth of chicks. The the breeding period recent introduction of drones, a method that is becoming widespread, has helped to complete a fairly accurate aerial survey In order to offset possible margins of error without having to penetrate into the in counting big groups on rest areas at colonies. high tide, additional techniques are often The weakness of these methods is that used, whereby samplings are carried out. most often the census period does not This consists in counting a small number necessarily tally with the moment when of sites considered to be representative the entire colony is gathered, which, and from which the overall numbers are however, is tempered by the fact that worked out by extrapolation. However, breeding is highly synchronised among it appears difficult to identify those colonial species. areas that best correlate with the overall

The status of waders and coastal seabirds on key natural sites of the West Africa’s coastline Relevant bird populations 12

RELEVANT BIRD POPULATIONS

Two groups of species are considered in this paper, i.e. waders and coastal seabirds.

Waders

Wader populations in question are those Archipelago in Guinea-Bissau. The period of the East Atlantic Flyway. Essentially, during which they remain on the West these are highly migratory species that Africa’s coastal area may be as long as six breed from Eastern Canada to Siberia, months and even eight months for some and overwinter along the Atlantic coast species, which gives an indication to the in Africa, particularly between the Bay key role that overwintering sites play in the of Arguin in Mauritania and the Bijagós life cycle of these species.

The status of waders and coastal seabirds on key natural sites of the West Africa’s coastline Relevant bird populations 13

With a medium size and a neutral colour in For instance, the Bar-tailed Godwit, which the browns and greys, waders generally live feeds on worms, blindly searches for food in groups at the interface of sea and land in the mudflats with its long beak, the nerve in the intertidal zone. At low tide, mudflats endings of which are extremely sensitive. are uncovered and therefore accessible to The curlew is also equipped with a long birds which can then feed on worms, crabs beak that it uses to catch crabs from their and molluscs that make up their diet. galleries. On the other hand, species with When the sea level rises again and covers short legs and beaks, such as the plover, up the mudflats, the birds fly to rest areas hunt on sight their preys that live on the near to the shore where they are often surface of mudflats. These differences in found in large groups. behaviour and food diet help the species concerned to live in harmony by allowing While from afar waders may give the for an efficient sharing of resources. Below impression of looking alike, they actually is a description of key species of waders differ significantly in terms of morphology found on the West Africa’s coastal area: and behaviour, depending on their diet.

The Eurasian Curlew Numenius arquata is the biggest of its family, also recognisable by its very long hooked beak. It feeds on crabs and worms. It breeds from Europe to Oural. The population of interest to us is in decline.

The Whimbrel Numenius phaeopus resembles the Eurasian Curlew but is of a smaller size. In winter, it mainly feeds on sand fiddler crabs. It breeds in Greenland, Island, Scandinavia and Russia. Its population is in decline.

The Bar-tailed Godwit Limosa lapponica – It is characterised by a very long beak. It feeds on worms. It is the migratory bird that holds the record of the longest stretches, i.e. 11,500 km flown in nine days without stopping nor eating. The population of interest to us breeds in Siberia and is in decline.

The status of waders and coastal seabirds on key natural sites of the West Africa’s coastline Relevant bird populations 14

The Common Redshank Tringa totanus - With its long red legs, it feeds on sand fiddler crabs, worms and small molluscs. It breeds in Norther Europe, and its population is in decline.

The Common Greenshank Tringa nebularia - With its long red legs, it feeds on sand fiddler crabs, worms and small molluscs. It breeds in Norther Europe, and its population is in decline.

The Ruddy Turnstone Arenaria interpres – It is a small and stocky bird with a long beak and orange legs. Its turns over stones or grass beds with its head in search for small crustaceans. It breeds from the North- East of Canada to the North-West of Russia, and its population is in decline.

The Dunlin, Calidris alpina – Characterised by a small size and a slightly curved black beak, it feeds on worms and small molluscs. Its breeding area spreads from Scandinavia to the North-West of Siberia. The population is either stable or in decline.

The Red Knot Calidris canutus – Of a medium size, this robust bird has a thick beak with which it feeds on molluscs, especially bivalve ones. It breeds in Siberia, and the population of interest to us is in decline.

The Curlew Sandpiper Calidris ferruginea – Small in size and with a slightly bent beak, it feeds on worms. It breeds in Northern Siberia, and its population is on the increase.

The status of waders and coastal seabirds on key natural sites of the West Africa’s coastline Relevant bird populations 15

The Sanderling Calidris alba – It is small and light grey, and has a black beak. It hunts crustaceans by running fast up and down the beaches to accompany the movement of the waves. It breeds at the far North around the Arctic Circle, and its population is stable.

The Little Sting, Calidris minuta – This is a very small bird with a short and thin-tipped beak. It breeds in Northern Scandinavia and Russia. It feeds on invertebrates, such as molluscs and small crustaceans. Its population is in decline.

The Black-bellied Plover Pluvialis squatarola is of medium size and has a short and strong beak. It feeds on sand fiddler crabs, worms and molluscs on the surface of mudflats. It breeds in the tundra in Siberia. Overall, its population is on the increase but in decline on its overwintering sites in Africa.

The Common Ringed Plover Charadrius hiaticula is a small and stocky bird with a short beak that breeds in the North-East of Canada, Greenland and Island. It feeds on small invertebrates on the surface of mudflats. Thepsammodroma subpopulation that overwinters in West Africa seems to be in slight decline.

The Kentish Plover Chararius alexandrinus – Small and with a black and thin beak, this species of wader breeds in Western Europe and in the North-West of Africa. It feeds on surface insects, small crustaceans and molluscs. Interpretation is not clear as to the trends but its population in West Africa appears to be in decline.

The Eurasian Oystercatcher Haematopus ostralegus – It has black and white feathers and a strong red-orange beak. It breeds in the countries bordering the North Sea and in Scandinavia. As its name implies, this bird feeds on bivalves and gastropods. Its population is in decline.

The status of waders and coastal seabirds on key natural sites of the West Africa’s coastline Relevant bird populations 16

Over the fifteen species of waders for in Europe or the breeding conditions for which the West Africa’s coastal area plays a bird populations that preferentially winter key role, ten or so globally show a declining in Europe have deteriorated considerably. trend. According to the report of Wetlands Generally, the environments in which International, on a total of 17,400,000 shorebirds live on West African sites individuals belonging to the benthivorous present a number of advantages linked to species surveyed in 2003 on overwintering the mild and stable weather (birds do not sites, nearly 2,500,000 individuals were need to store and carry fat), the predictable missing in 2014. The report nonetheless accessibility of feeding grounds, as a result noted that as far as African overwintering of the regularity of the tides, as well as to birds were concerned, the deficit share high productivity, even though the benthic only amounted to 200,000 individuals. biomass is less significant compared to This may suggest that wintering conditions European sites, including the Wadden Sea.

Coastal seabirds

Contrary to the abovementioned waders, caught alive. A specific characteristic of seabirds covered by the Plan of action the tern’s feeding behaviour is that it dives breed in West Africa and migrate over from a relatively high altitude (up to fifteen short distances. They gather in colonies at metres) to catch its preys. The Slender- nesting time and, to this end, choose islets billed Gull and the Grey-hooded Gull where there is naturally no predator or catch their preys on the surface. Species human being and where they nest on the considered are as follows: ground. Basically, they all feed on fishes

La Caspian Tern Hydroprogne caspia is the largest of all terns. It is also recognisable by its large beak that becomes bright red at the beginning of the breeding period and then turns orange. Caspian Terns gather in colonies of variable sizes, ranging from a few dozens to several thousands of couples. Depending on the sites, breeding takes place from February to November, with each couple laying one to three eggs. Located between Mauritania and Guinea, nesting sites are more often sandy and rocky islets (on the island of Kiaone in the Bay of Arguin). Although essentially feeding on fishes caught alive, the Caspian Tern can often show itself to be opportunistic by, for instance, taking advantage of bycatches or even eating young sea turtles at hatching. The size of the subpopulation of interest to us was estimated at 15,000 to 20,000 couples, with a seemingly upward trend.

The status of waders and coastal seabirds on key natural sites of the West Africa’s coastline Relevant bird populations 17

The Royal Tern Thalasseus maxima. The West African subspecies Albididorsalis breeds from Mauritania to Guinea. The nesting population, estimated between 85,000 and 105,000 couples, appeared to be stale (Wetlands International 2015, Dodman 2014, Veen et al. 2007, 2011). The Royal Tern frequently changes nesting areas from one year to the next, although there is only a limited number of identified potential sites available to it. The size of the colonies it often forms varies from a few hundreds to over 10,000 couples that lay eggs in a synchronised manner between April and May, at the rate of one egg per couple.

The Slender-billed Gull Larus genei is a West African resident species that breeds from Mauritania to Guinea-Bissau. Nesting individuals are comprised between 8,000 and 10,000 couples (Veen et al. 2007, 2011), and the population is considered to be stable although figures can fluctuate sharply from one year to the next. Colonies usually settle in on islets from April to May, and consist of a few dozens to hundreds of couples that lay one to three eggs each. The Slender-billed Gull feeds on fishes but also occasionally on small crustaceans and insects.

The Grey-hooded Gull Larus cirrocephalus lives in West Africa. It breeds on coastal islets but also in inland wetlands. The most important sites where it is found are located in Senegal, Gambia and Guinea- Bissau. Its population varies in size every year and appears to be in decline since 1997 (Wetlands International, 2015). It includes 8,000 to 10,000 couples (Veen, et al. 2007, 2011) that breed from April to June, each laying two to three eggs. This species hunts fishes for food but is also an opportunistic generalist capable of feeding on household refuse, fruits of the palm oil and even eggs from other species when colonies are disturbed.

The status of waders and coastal seabirds on key natural sites of the West Africa’s coastline STATUS OF COASTAL WATERBIRDS ON KEY SITES

Banc d’Arguin National Park

Short site description essentially depends on seagrass beds that cover almost sq. 500 km of intertidal The Banc d’Arguin National Park is a vast mudflats but also on the inputs of the coastal wetland located in Mauritania upwelling of the Canary Current. The Park between Cap Blanc in the North and Cap is recognized worldwide for its biodiversity Timiris in the South. It is one of the three and especially for its bird populations of key sites used by shorebirds that migrate global importance, its sea mammals and from the Arctic to South Africa through the sea turtles (Araujo and Campredon, 2017). East Atlantic Flyway. Primary production

The status of waders and coastal seabirds on key natural sites of the West Africa’s coastline Status of coastal waterbirds on key sites 19

Comprising areas covered with seagrass with time to 1,459,000 individuals in beds, mudflats and sandbanks, channels, 2014 (see Figure 1). However, a full count islands and islets, the Banc d’Arguin performed in 2017 showed a slightly National Park is one of the largest marine higher number of 1,725,000 individuals protected areas of Africa (with a surface for all waterbirds. The review of the full area of sq. 11,200 km) and listed both counts, corroborated by partial counts as a Ramsar site and a UNESCO World undertaken by the PNBA staff as well by Heritage site. It also fosters significant researchers of the Netherlands Institute cultural values and contributes in a very for Marine Research (NIOZ), has helped to meaningful manner to fishery economics in establish a significant trend for six species Mauritania. It is home to a community of only, five of which are negative, including fishermen, the Imraguen, who are the only three species of waders, i.e. the Eurasian ones allowed to fish in the waters of the Curlew, the Bar-tailed Godwit and the Red Park using “sailing launches”.. Knot (the other two being the Long-tailed Cormorant and the Eurasian Marsh Harrier, Waders with the Eastern White Pelican as the sole exception of a significant rising trend). For Since the late 1970s, the global importance all other species, there is no adequate data of the Banc d’Arguin National Park for to derive significant trends. It appears, migratory waders has always been however, that those species that depend recognised. Several counts carried out by on intertidal mudflats for survival are various teams of researchers across the declining drastically compared to species entire area showed that the total number that depend on infra-coastal or marine of individuals amounted to 2,380,000 in areas per se (Oudman et al. 2017). 1980, and that this markedly decreased

FIGURE 1: Full counts of waders carried out at the Banc d’Arguin National Park between 1978 and 2014 (in Arauj & Campredon, 2017)

2.5M

2.3M

2.1M

1.9M

1.7M

1.5M

1.3M 1978 1980 1997 2000 2001 2006 2014 Trotignon NOME WIWO (37) WIWO (37) WIWO (37) WI (20) WSFI (39)

Total waders (actual counts) The number of sites surveyed is in brackets. Data from Trotignon et al. (1980), Altenburg et al. (1982), Hagemeijer et al. (2000), Smit et al. (2001 – not published), Diagana et Dodman (2006), van Roomen et al. Linear trend (total waders) (2015) and PNBA database.

The status of waders and coastal seabirds on key natural sites of the West Africa’s coastline Status of coastal waterbirds on key sites 20

Seabirds show significant annual fluctuations that are difficult to interpret. Analyses have The Banc d’Arguin National Park hosts revealed a statistically significant trend for populations of colonial birds of global the Long-tailed Cormorant whose nesting importance. With its islands and islets, it numbers are declining, as well as for the creates favourable breeding conditions for Eastern White Pelican which is on the these birds by providing them protection increase. Table 1 summarises the average, from most of the predators, a key factor minimum and maximum number of when it is known that these species nest couples accounted for in the PNBA during on the ground. The number of individuals the various counts. per species and the overall numbers

TABLE 1: Summary of information available on the number of colonially-nesting birds in the Bay of Arguin

Nesting couples Species Average Min Max Trend

African Cormorant 4,688 1,400 8,130 Upward

Long-tailed Cormorant 2,012 900 2,900 Downward

Eastern White Pelican 2,192 400 3,800 Upward

West African Reef Heron 862 280 1,900 Downward

Mauritanian Heron 1,738 1,070 2,400 Downward

Eurasian Spoonbill balsacii 2,516 1,500 4,990 Stable

Greater Flamingo 11,463 6,600 16,500 Stable

Slender-billed Gull 1,411 870 1,780 Upward

Grey-hooded Gull 35 9 70 Downward

Gull-billed Tern 978 180 1,950 Downward

Caspian Tern 5,691 1,800 10,900 Upward

Royal Tern 12,526 5,630 19,353 Upward

Common Tern 219 15 900 Downward

Bridled Tern 463 48 900 Downward

Little Tern 91 10 210 Downward

Data from Naurois 1969 (1959 – 1965), Campredon 1987, 2000 (1984 – 1985), Hafner et al. 1999 (1997 – 1999), Zwarts (1998), Veen & Dallmaijer (2004/2005/2007).

The status of waders and coastal seabirds on key natural sites of the West Africa’s coastline Status of coastal waterbirds on key sites 21

The trends noted for the nesting numbers Conclusions on the site and of the four coastal seabird species of ecological capacity of the interest to us are positive for the Royal Stern and the Caspian Tern as well as for PNBA the Slender-bill Gull. With regard to the Shorebirds in the Banc d’Arguin have seen couples of the Grey-hooded Gull breeding their populations decreased by nearly in the PNBA, their numbers were too small one-third since the first full count in this to establish any trend. area. In spite of the significant efforts that have gone into scientific research, a unique endeavour in the region, this Nevertheless, it is known decrease remains difficult to interpret. Environmental conditions within the PNBA that four of the five have relatively remained unchanged, islands used by the Royal apart from the fishing effort that has developed considerably from 1980 to Tern are prone to partial date. The important drop in the numbers of the Long-tailed Cormorant, a resident flooding at spring tide piscivorous species, seems to indicate that conditions have deteriorated at the local Nevertheless, it is known that four of the level. Researchers do not rule out that the five islands used by the Royal Tern are decrease in the population of the skate prone to partial flooding at spring tide in Rhinoptera marginata as a result of fishing April, which often results in egg clutches affects the dynamics of grass beds. In the being carried away. Indeed, on the islets of same vein, while the reduced number of the Zira, flamingos, pelicans and marguerites Red Knot may be partly attributable to the stand quite low on the water, whereas the deterioration of its Wadden Sea migratory space available on the island of Arel may stopover, it also stems from the fact that not be sufficient due to the presence of the population of its favourite prey in the other colonial species. Also formerly used PNBA, i.e. the bivalve Dosinia isocardia, as nesting sites by the Royal Tern were the has become smaller as the density of islands of Cheddid and Touffat, but these the Anadara senilis has increased, which now host jackals. The nesting population of itself results from the decline of the the Royal Tern is therefore likely to change Anadara senilis’ key predators, i.e. rays and over the long term in connection with sea Eurasian Oystercatchers. Bearing in mind level rise and their close dependency on that benthivorous species are much more islets. affected than piscivorous species(Oudman et al. 2017), it is therefore possible that The Caspian Tern is a more generalist the impact of fishing on bird populations species compared to the Royal Tern when is rather most keenly and indirectly felt on it comes to nesting habitats, as 60% of its the benthos than on the availability of fish population breed on rocky islands. Like the stocks. Other cascade effects are currently Royal Tern, a significant proportion of the being considered as research assumptions, couples of Slender-billed Gulls nest close including the role of the Greater Flamingo to the sea, often in the very vegetation in structuring the profile of mudflats and of the swash mark, thereby making them the consequences of the reduced size of vulnerable to sea level rise in the PNBA. the population of this species, possible due to this species feeling better attracted to the sites in the lower delta of the Senegal River (El Hacen et al. 2017).

The status of waders and coastal seabirds on key natural sites of the West Africa’s coastline Status of coastal waterbirds on key sites 22

With respect to coastal seabirds covered two species tend to nest on islets near by the PAZHOC Plan, the PNBA confirms the lines of high spring tides, particular that the Plan is relevant vis-à-vis nesting attention must be accorded to the impact colonies of Caspian Terns, Royal Terns of sea level rise. and Slender-billed Gulls. As the last

Senegal River lower delta

Short site description Flamingo, the Caspian Tern and the Royal Tern as well as the Slender-billed Gull, Diawling National Park (PND), Aftout-es- that nest on an islet in Aftout-es-Saheli. Saheli and Chott Boul The Park forms part of the Transboundary Biosphere Reserve of the lower delta of the The Diawling National Park, covering a Senegal River that consists of protected surface area of sq. 15,600 hectares, is areas in Senegal, particularly the Djouj located in the far South-West of Mauritania National Bird Sanctuary, a World Natural at the mouth of the Senegal River. It Heritage site and the Langue de Barbarie extends on another 19,500 hectares National Park. through Aftout-es-Saheli (a buffer zone) and Chott Boul (a peripheral zone listed as Langue de Barbarie National Park (PNLB) a Ramsar site). The whole of the section of the delta situated in Mauritania was deeply The Langue de Barbarie National Park modified following the construction of the stretches on 2,000 hectares along the Diama dam, the consequence of which was Atlantic Ocean from the mouth of the that almost all waterbirds had disappeared Senegal River southward. It appears from the area. A considerable effort has as a sandy peninsula which includes a been undertaken along with the creation lagoon area with an islet conducive to the of the Park to rehabilitate the area through reproduction of colonial birds. In 2003, a number of water works, which helped an artificial channel was dug across the to recreate artificial conditions for the Langue de Barbarie strip to protect the functioning of the estuary. Since then, the city of Saint-Louis from flooding, which site has been recolonised by waterbirds in entailed heavy repercussions on the naval a spectacular manner. ecosystem. This bird island suffered severe erosion, with its surface area decreasing from 1.5 hectare to 1 hectare. Recently, a It is a site of major importance protective belt of laterite rubbles was built around the islet to thwart erosion. The for overwintering shorebirds island is entirely covered with vegetation, part of which is removed every year by the The site of the Diawling National Park Park staff to create places for terns to nest comprises estuarial and intertidal areas, on the ground. mangroves and salt flats, an alluvial plane, lakes, ponds and a lagoon. It is a site Waders of major importance for overwintering shorebirds. When the water level is high Information on waders in the lower delta of enough, it also plays a key role for the the Senegal River, and more particularly on reproduction of colonial species, such the two sites of interest to us, is available in as the Lesser Flamingo (the only nesting a very piecemeal fashion. The total number colony known in West Africa), the Greater of waterbirds is provided on an annual

The status of waders and coastal seabirds on key natural sites of the West Africa’s coastline Status of coastal waterbirds on key sites 23

basis for the Diawling National Park (see The two key species encountered in the Figure 2). This fluctuates between 270,400 area are continental waders, i.e. the Black- and 87,000 individuals depending on the tailed Godwit and the Ruff, the population year, with waders accounting on average of the latter having decreased from nearly for 6% of the total number (Ba et al. 2018). 175,000 to 25,000 individuals from 1992 Based on information retrieved from Triplet to 2008, a drop explained by the fact that et al. (2009) for the section corresponding rice grains on the surface of the ground to the lagoons in Saint-Louis, it appears are no longer accessible to birds because that the number of waders dropped the rice fields are cut too high. Apart from drastically after a breach was made in these two species, not directly covered by the Langue de Barbarie strip. Below is a the PAZHOC Plan, the lower delta of the summary in number of individuals of the Senegal River appears to be of incidental data retrieved from the literature on the importance for waders, in view of the species of waders of interest to us and number of birds present on other sites. that overwinter in the sensu lato lower delta, regardless of the date of observation (in Isenmann et al. 2010):

Eurasian Curlew 100-200

Common Redshank 150

Red Knot 20,000

Little Stint 5,000 - 10.000

Dunlin Max. 20 000

Common-ringed Plover 5,000 - 15,000

Kentish Plover 1,400

Whimbrel 300

Common Greenshank 300 - 775

Sanderling 4,000 - 5 ,00

Curlew Sandpiper 3,000 - 10,000

Black-bellied Plover 1,500 - 2,000

Little-ringed Plover 300 - 1,700

The status of waders and coastal seabirds on key natural sites of the West Africa’s coastline Status of coastal waterbirds on key sites 24

FIGURE 2: Trends in total numbers of waterbirds in the section of the lower delta located in Mauritania

300k 270k

248k 237k 250k 231k

200k 183k 175k

150k 144k 136k

100k 112k

87k

50k 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017

Coastal seabirds that the reproduction of these species in the Aftout is irregular, being closely related Breeding data available on the species to water levels. covered by this document are fragmented. In contrast, data are more accurate when Concerning the Diawling National Park, Ba it comes to the Royal Tern that breeds in et al. (2018) reported, without specifying the Langue de Barbarie National Park (Veen the year, an average number of 1,500 et al. 2015) where the number of couples couples of Caspian Terns, 100 to 200 fluctuates between 1,200 and 3,000 ((Table couples of Royal Terns and a dozen of 2). The little information providing details couples of Grey-hooded Gulls, for an on other species mentions the Slender- average total number ranging from 10,000 billed Gull (298 nests in 2015) and the to 18,000 couples, all nesting species Grey-hooded Gull (500 couples in 2016). combined. The African Cormorant and the The total number of nesting couples, all two species of Flamingos accounted for species combined, varies between 6,000 the bulk of this figure. It is known, however, and 7,000 depending on the year.

TABLE 2: Number of nesting couples of Royal Terns on the bird island of the PNBA

Years 1998 2000 2001 2003 2004 2005 2015

Number of couples 1,650 1,400 1,700 1,672 2,171 1,193 3,000

The status of waders and coastal seabirds on key natural sites of the West Africa’s coastline Status of coastal waterbirds on key sites 25

Conclusions on the site and of mudflats. Although relatively small in ecological capacity of the size, the Langue de Barbarie National Park is pivotal for coastal seabirds, particularly PNLB the Royal Tern. The species to which the Park is home, however, face difficulties in The ecological profile of the sites breeding due to the fact it is subjected associated with the lower delta of the to erosion and that egg clutches are Senegal River makes them less attractive frequently submerged at spring tides. The to waders compared to the PNBA or the space available for colonies is therefore Bijagós Archipelago, for being strongly reduced, let alone when Pelicans use the influenced by the presence of fresh waters, strip as a rest area at high tide while their the variability and unpredictability of usual rest area is submerged. water levels and the lack of large areas

Saloum Delta National Park (PNDS)

Short site description The PNBA is integrated in the 18,000 hectares Biosphere Reserve of the Saloum The Saloum Delta National Park has a delta, and is settled by human populations surface area of 73,000 hectares and is who make a living on shell harvest and situated along the Atlantic coast of Senegal fishing. Moreover, it is a repository of immediately to the North of the border important cultural values for which it with the Gambia. It consists of the delta of was entered on the list of UNESCO World the Saloum, Diombos and Bandiala Rivers, Cultural Heritage. It has also been listed as and features mangrove-lined channels, a wetland of global importance under the lagoons, intertidal mudflats, sandbanks and Ramsar Convention. islands, a whole mosaic of environments suitable for biodiversity. A number of Waders islets are located off the coast, including Only a fraction of detailed data on the the Bird Island, a breeding hotspot for population of waders within the PNBA seabirds. The region is under the influence exists. Indeed, Diop et al. (2018) only of the upwelling of the Canary current and pointed to the regular presence of about also benefits from the mainland inputs of 100,000 overwintering seabirds. In terms organic matter and nutrients as well as of absolute value, the number of waders from the productivity of mangroves. varies between a maximum of 33,750 and a minimum of 16,480 individuals (see Figure 3).

FIGURE 3: Summary of waterbird counts in the overwintering period in the PNDS (in Diop et al. 2018)

35k

25k

15k

2012 2013 2014 2015 2016 2017 2018

Cormorans Sternes Hérons Laridés Limicoles

The status of waders and coastal seabirds on key natural sites of the West Africa’s coastline Status of coastal waterbirds on key sites 26

Coastal seabirds 2009, 2011, 2012, 2013, 2014, 2015). It appears from the counts that the PNBA is More detailed information is available on home to nearly 50% of nesting birds in the coastal seabirds in view of the significance total population, with a maximum number of the PNBA site for these species. Nesting of 43,000 couples counted in 1999. The colonies have been regularly monitored annual findings of these counts are shown for many years, notably with regard to in Figure 4. breeding Royal Terns (Veen et al. 2006,

FIGURE 4: Trend of the number of nesting couples of Royal Terns in the Saloum Delta National Park from 1998 to 2015 (Veen et al. 2015). N/A: data not available.

50k

40k

30k

20k

10k N/A N/A N/A N/A 0 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2008 2010 2011 2012 2013 2014 2015

For other species, data are rather grew from an estimated 7,500 in 2001 to incomplete. The number of Caspian Terns 12,255 and then 15,700 in 2011 and 2013, ranged from 5,900 (in 2000) to 7,500 respectively, although these figures must couples (in 1999, 2004 and 2011), with be taken with precaution since different an average number of 6,460 couples in count methods were used (Veen, 2013). 2013. As regards the Slender-billed Gull, In the overwintering period, a number an estimated number of 6,000 to 9,000 of seabirds, especially the Caspian Tern couples was counted from 2001 to 2006, and the Slender-billed Gull, remain in the a figure that subsequently dropped to Saloum delta, as shown by international 3,900 couples in 2011. In the case of the counts (Figure 5). Grey-hooded Gull, its number of couples

FIGURE 5: Size of overwintering populations for the four species of coastal seabirds in the Saloum Delta National Park (in Diop et al. 2018).

0 2012 2013 2014 2015 2016 2017 2018

Mouettes à tête grise Goélands railleurs Sternes caspiennes Sternes royales

The status of waders and coastal seabirds on key natural sites of the West Africa’s coastline Status of coastal waterbirds on key sites 27

Conclusions on the site and species, which seems to confirm that the ecological capacity of the disturbance observed during that year was significant. The island of Jakonsa appears PNBA to play a crucial role for the Slender-billed The overall number of colonial birds nesting Gull, for hosting 84% of its population on the PNBA site reaches 40,000 to 60,000 in 2013. Since the start of the counting couples depending on the year, thereby exercise, the size of the Grey-hooded Gull indicating how important the PNBA is at is seen to be rising, a peak of about 15,000 the regional and global level. In this total, couples was even reached in 2013. the Royal Tern accounts for a large portion, It appears that the bird island, a traditional since the site hosts on average 50% of the egg-laying site for the four species, is albididorsalis sub-species present in West subject to considerable erosion which Africa. Significant inter-annual variations gradually eats into the space used by are reported, however, with a minimum of colonies and may entail flooding risks 17,000 couples and a maximum of 43,000 for the nests at high spring tide. Also couples. noteworthy is the nest predation risk that The PNBA also plays a key role for the has been reported several times as well as Caspian Tern, with an estimated 6,000 to the disturbance caused by unaccompanied 7,500 couples, representing 30% to 40% of tourist visits. The setting-up of observation the West African population. Fragmentation towers in the immediate vicinity of egg- was also reported in the number of this laying sites in the past has had a negative species, although the bird island seemed impact which possibly could explain the to hold its dominant position as it was still drop in numbers in 2011 and the dispersal home to 90% of the population surveyed of colonies to the islets of Ansoukala and in 2013. Jakonsa. As these islets are now regularly occupied, they should be closely monitored during the nesting period, from February to In 2011, there was a downward July, taking into consideration the risks of nest predation and disturbance by tourists, trend in the number of fishermen or community members. It other species, which should also be noted that activities such as sand extraction, tree planting and seems to confirm that the illegal camping on the islet of Jakonsa are likely to seriously jeopardise the PNBA’s disturbance observed during ecological capacity. While the existence of alternative egg-laying sites is a positive that year was significant factor, it nevertheless involves a number of monitoring constraints, with repercussions Depending on the year, the number of in terms of means of implementation for Slender-billed Gulls would vary between which it would be good to contemplate 2,500 to 9,000 couples. In 2011, there was solutions. a downward trend in the number of other

The status of waders and coastal seabirds on key natural sites of the West Africa’s coastline Status of coastal waterbirds on key sites 28

The Bijagós Archipelago Short site description Covering a total surface of one million hectares, the Archipelago has a remarkable The Bijagos Archipelago emerges from diversity which provided a case for listing the continental shelf off the coast of it as a biosphere reserve and a Ramsar Guinea-Bissau. It is the only active deltaic site as well as for creating three marine archipelago on the West Africa’s coast, and protected areas. The Bijagos’ traditional consists of 88 islands and islets, including management method based on cultural 21 that are permanently inhabited by the and religious values has contributed to the Bijagos community. Islands are separated conservation of the site, including through by a network of channels along which the establishment and protection of sacred are found mangroves and mudflats that islands and forests which make up true represent a surface area of sq. 1,200 km biodiversity oases (Biai 2015, Campredon & and make up together the largest intertidal Catry, 2017). zone on the African continent. Also beneficial to the Archipelago are the inputs Waders of organic matter and nutrients from rias The Bijagos Archipelago, next to the as well as the productivity of mangroves. Banc d’Arguin, has the second largest concentration of shorebirds in Africa, with Covering a total surface an estimated 700,000 Palearctic waders of one million hectares, that spend nearly half of their existence on the Archipelago during the overwintering the Archipelago has a season. A summary of the counts and population estimates is provided in Table 3 remarkable diversity below (Henriques, 2019).

The status of waders and coastal seabirds on key natural sites of the West Africa’s coastline Status of coastal waterbirds on key sites 29

TABLE 3: Summary of the counts and estimates of shorebirds in the Bijagos Archipelago

Period of % Estimation Pop Years Areas covered Count method Source count covered method estimate

1982 - 1983 December- Bubaque, Bolama, In situ low-tide Density Poorter & Zwarts 28.1 699,120 1986 - 1987 February Bijagós counts extrapolation (1984); Zwarts (1988)

October- 16 areas in 14 In situ low-tide Density 1992-1993 64 710,000 Salvig et al. (1992) May islands counts extrapolation

Aerial survey + 1994 December Full coverage 54 Detection rate 750,000 Salvig et al. (1997) ground counts

February- 1994 November April- In situ low-tide Maximum total 1995 Bubaque, Soga N/A 15,000* Salvig et al. (1997) September counts count 1997 January- March

January- 44 areas in 18 In situ low-tide Density Frikke et al. (2002); 2001 64 871,750 February islands counts extrapolation Dodman & Sá (2005)

May 9 areas counts in 2 July In situ low-tide Maximum total 2009 marine protected N/A 23,241* Monteiro (2011) counts count September areas November

August 9 areas counts in 2 In situ low-tide Maximum total 2010 October marine protected N/A 31,092* Monteiro (2011) counts count areas December

August 9 areas counts in 2 In situ low-tide Maximum total 2011 October marine protected N/A 17,979* Monteiro (2011) counts count areas December

171 points in all In situ low-tide Density van Roomen et al. 2014 January 58 481,395** Bijagós counts extrapolation (2015)

*Count that failed to give a global estimate of the population. **Estimate for all mudflats in Guinea-Bissau and in the Bijagos Archipelago (in Henriques, 2019).

The status of waders and coastal seabirds on key natural sites of the West Africa’s coastline Status of coastal waterbirds on key sites 30

The review of the findings from the five same period and by 8.5 times compared available estimates points to worrying to the first estimate made in 1986/1987. trends with regard to key species (Figure Other once numerous species also show 6). It may thus be noted that Curlew a downward trend, although in a less Sandpipers have sharply decreased in sensitive manner, such as the Red Knot, number, being four times less than they the Common Redshank and the Black- were between 2011 and 2014. The same bellied Plover. In contrast, positive trends trend applies to the Little Stint whose have been noted for the Bar-tailed Godwit, population decreased by half during the the Whimbrel and the Sanderling.

FIGURE 6: Census findings for waders, per species and year, in the overwintering season in the Bijagos Archipelago (Henriques, 2019)

600k

500k

400k

300k

200k

100k

0 Calidris Limosa Calidris Calidris Tringa Pluvialis Charadrius Numennius Arenaria Charadrius Calidris Numenius Haematopos ferruginea lapponica minuta canutus toutanus squatarola hiaticula phaeopus interpress alexandrinus alba arquata ostralegus

1986/87 1992/93 1994 2001 2014

The status of waders and coastal seabirds on key natural sites of the West Africa’s coastline Status of coastal waterbirds on key sites 31

Coastal seabirds because of the introduction of free-ranging pigs (IBAP, 2008). A colony of terns has Not many counts and studies are available recently found a home on the islet of on the Royal Tern and the Caspian Tern Bantambour at the edge of the island of in the Bijagos. The counts performed Jeta near to the mainland (although it does by Altenburg et al. (1992), Quade (1994), not belong to the Archipelago per se). Its Schmanns et al. (1997) and Brenninkmeier size was estimated at 25,281 couples in et al. (1998), and summarised by Dodman 2015 (Veen et al. 2015). et al. (2004, 2005), however, revealed Nesting couples of Caspian Terns, Slender- nesting colonies of global importance for billed Gulls and Grey-hooded Gulls are these two species as well as for the Grey- estimated at a few hundreds, with the hooded Gull. Lower estimates, ranging process taking place on the islet of Acapa from 430 to 600 couples, were obtained Imbone at the edge of the Orango National for the Slender-billed Gull. Figure x shows Park. When and where these species build the location of the key nesting sites of their nests cannot be anticipated, and colonial species (without distinction). therefore only a monitoring work all year A full count of Royal Terns performed in round and across all the island and islets 2006 showed that 19,922 couples were will help to assess their numbers in an present on the island of Cavalos. However, accurate manner. the site was later on abandoned probably

FIGURE 7: Location of the nesting sites of the species of colonial waterbirds in the Bijagos Archipelago

The status of waders and coastal seabirds on key natural sites of the West Africa’s coastline Status of coastal waterbirds on key sites 32

Conclusions on the site and positions therefore appear to be relatively ecological capacity of the narrow with little overlap, apart from those species that feed on violinist crabs, which Bijagos Archipelago is propitious to cohabiting among large numbers of individuals (Lourenço et al. The Bijagos Archipelago is the second 2017). largest overwintering site for coastal waders of the East Atlantic Flyway, but also The count results, however, indicate a stop-off for individuals overwintering that the population size has decreased further South. Its importance partly over time. It is difficult to interpret this results from the substantial stretch of trend, given that the ecological features intertidal mudflats. Although the biomass of the Archipelago do not seem to have of benthic organisms is weak compared undergone particular changes since the to mudflats in temperate latitudes, this first counts. Factors likely to explain the weakness is undoubtedly compensated by decrease include the following, as listed by higher productivity and diversity. Catry et Henriques (2019): al. (2016) have shown that resources are effectively shared among the species, with º a weaker ecological capacity of the Whimbrel, the Common Redshank and intermediary sites or breeding areas for the Black-bellied Plover mainly feeding on the populations concerned (Stroudt et violinist crabs, while the Bar-tailed Godwit, al. 2006, Zwarts et al. 2009); the Curlew Sandpiper and the Common- º difficulties in performing the counts, ringed Plover eat Polychaeta and that the due to the stretch of the site but also Red Knot catches bivalves for food. Trophic to the fact that part of the birds use the mangrove (either perching on tree branches or standing on salt marshes), Although the biomass of benthic making their observation difficult; organisms is weak compared º the overexploitation of natural resources by human beings, which is likely to to mudflats in temperate impact directly or indirectly the preys latitudes, this weakness is of waders. Although the pressure from fishing or shell harvest is significant, undoubtedly compensated by there is no indication, based on current knowledge, of any influence on the higher productivity and diversity status of benthos;

The status of waders and coastal seabirds on key natural sites of the West Africa’s coastline Status of coastal waterbirds on key sites 33

º increasing disturbance: the recent trend Factors likely to influence the reproduction towards the intensification of waterbird of coastal seabirds on the Archipelago hunting is, so far, not sufficiently seem more obvious. The first such factor is marked to influence stationnements in the introduction of free-ranging pigs on the a significant way; island of Cavalos, a site known for hosting a large colony of Royal Terns in the past º pollution from organic matter or heavy while the second lies in the erosion of islets metals, but this remains at very low and related flooding risks for egg clutches. levels (Coelho et al. 2016, Catry et al. In this regard, it should be noted that the 2017, Mullié 2017) except for the high availability of this type of environment levels of cadmium noticed in Anadara is low, as most of the islets across the senilis; Archipelago are covered with mangroves º climate changes, which, through sea or big trees less propitious to the arrival of level rise for instance, could impact tern colonies. For the moment, however, the length of the period during which these seem to have found an alternative mudflats remain uncovered and, solution by falling back on the island of consequently, the accessibility of preys Bantambour that is located North of the (Galbraith et al. 2002, Austin & Rehfisch island of Jeta. 2003, Lourenço et al. 2013).

The status of waders and coastal seabirds on key natural sites of the West Africa’s coastline CONCLUSION

Bijagos Archipelago which are home to 2 to All the counts and studies 3 million individuals in the overwintering carried out since the 1980s on period for 6 to 8 months, depending on the species. These sites also serve as a coastal seabirds have shown stopover site for waders overwintering further South. In the same manner, the and corroborated the utmost lower delta of the Senegal River and the importance of West Africa Saloum delta are of crucial importance for colonial seabirds during the breeding All the counts and studies carried out season, especially for the four species since the 1980s on coastal seabirds have considered under the Plan of action. shown and corroborated the utmost The importance of the Bay of Arguin and importance of West Africa. With regard to the Bijagos Archipelago for waders lies coastal waders, they are essentially found in the considerable stretch of intertidal on two sites, i.e. the Bay of Arguin and the mudflats, the productivity and diversity

The status of waders and coastal seabirds on key natural sites of the West Africa’s coastline Conclusion 35

of benthic organisms as well in the These are highly migratory birds whose arrangements by which competition is survival also depends on what they go limited among species and indeed among through in the migratory process or during gender within the same species, such as in the breeding period (Piersma & Lindström the case of the Bar-tailed Godwit, due to 2004). The reasons for their reduced their differences in morphology, behaviour numbers can therefore be traced to very and diet, and to the subtle space-sharing remote sites. For instance, it is known that mechanisms in place (Catry et al. 2016). bivalve resources are no longer abundant The ecological features of these sites are as they used to be in the Wadden Sea, a relatively predictable in terms of climate refuelling site crucial for the Red Knot and resource accessibility. Birds do not and located halfway between West Africa need to fatten up nor do they need, as a and the peninsula of Taïmyr where this result, to carry the excess fat on a daily species breeds. More generally, it appears basis. that declining wader species of the East Atlantic Flyway are also those for which The same research work, however, has the Wadden Sea represents a fundamental highlighted a decrease in the total number migratory stage (Stroudt et al. 2004). of waders both in the Banc d’Arguin National Moreover, the impact of climate changes Park and on the Bijagos Archipelago. In on breeding sites is already apparent. A statistic terms, this decrease is more number of studies have underscored, for pronounced in the specific case of the example, that the lag between arthropod Eurasian Curlew, the Bar-tailed Godwit and production peaks and Red Knot hatching the Red Knot in the Banc d’Arguin. In the peaks – formerly synchronised but now Bijagos, the trend is also clearly downward occurring earlier because of the global for the Curlew Sandpiper and the Little warming – has consequences on the Stint but less evident for other species. growth of juveniles whose beaks are now Several factors are put forth by researchers shorter (Gils et al. 2016). to explain this phenomenon. The reasons for the decline in numbers may also be inherent to overwintering sites These are highly migratory birds in West Africa, although no major structural whose survival also depends change has been reported on these sites. Some researchers have brought to light on what they go through in the consequences of ray overfishing on the landscape structure of mudflats, the the migratory process or stretch of grass beds as well as bivalve populations, underscoring that the sharp during the breeding period decline of rays causes a proliferation of Anadara to the expense of Dosinia, the Red First, there is a need to consider the Knot’s staple food. uncertainties that result from the difficulties inherent to the counting The impact of climate changes can exercise, especially when it comes to also be felt on overwintering sites. For sizeable groups on the largest sites, instance, rising air temperatures may with the ensuing risk of underestimating entail physiological consequences during smaller, less numerous or less visible the moult, which takes place when species within groups that are multispecies birds arrive in September-October in or ignoring individuals that use closed the hottest period, and are likely to lead environments, such as mangroves, as a to hyperthermia episodes (Leyrer et al. rest area at high tide. 2013). It is also possible that sea level rise impacts the morphology of mudflats

The status of waders and coastal seabirds on key natural sites of the West Africa’s coastline Conclusion 36

as well as birds’ spatial and temporal disturbance due to tourist activities and accessibility to food sites (Galbraith et the introduction of free-ranging pigs on an al. 2002, Austin & Rehfisch 2003). Another island likely to be home to large colonies consequence could be the creation of new of Terns in the Bijagos. intertidal spaces gained on the mainland, The uncertainties surrounding the reasons as was the case in the Bay of Arguin. for the decline of waders and the risks that potentially threaten all coastal birds, as a result of the short term degradation The impact of climate of coastal ecosystems and the long term changes can also be felt impact of climate changes, must spur stakeholders to step up their efforts for the on overwintering sites protection of wetlands and the birds that depend on them. Following the example of the actions carried out under the PAZHOC The overall status of coastal seabird species Plan, it is important to encourage the falling under the Plan of action looks good, establishment of partnerships on the scale at least for Terns and the Slender-billed of the flyway in order to promote scientific Gull whose populations are considered research, the training of national managers to be stable or on the increase (Veen and the strengthening of national bodies in 2015, van Roomen, 2015). Although count charge of environmental conservation. techniques have improved, particularly Birds must not only be considered for with the introduction of drones, it remains their intrinsic value as components difficult to get a synchronised picture of of biodiversity. Their functions in the the total size of nesting populations due to maintenance and balance of coastal the variability of the breeding periods. It is ecosystems must also be recognised. therefore important to consider the count Equally of interest is their role as results with precaution. Indeed, precaution indicators of changing environments. This must be exercised because of the threats is particularly true of waders which fly over facing colonial birds in the more or less large parts of the globe during their annual long term. Observers have noted on all the cycle across a wide range of biomes and sites that erosion is gaining islets, which climate zones and which, on that account, provide a nesting habitat to these species, can serve as “integrative sentinels” for the and that clutches are often submerged. global changes our Planet is currently going Given the sea level rise phenomenon, these through (Piersma & Lindström 2004). threats need to be closely monitored. Other threats include nest predation,

The status of waders and coastal seabirds on key natural sites of the West Africa’s coastline New intertidal spaces gained on the mainland at the edge of the Bay of Arguin as a result of sea level rise (photo En Haut!) BIBLIOGRAPHY

º Altenburg W, Engelmoer M, Mes R, Piersma T., 1982. Wintering waders on the Banc d’Arguin, Mauritania. Report of the Netherlands Ornithological Expedition 1980. Communication Nº 6, Wadden Sea Working Group.

º Araujo A & P Campredon, 2017. The Wetland Book. Banc d’Arguin, Mauritania. In C. M. Finlayson, G. R. Milton, R. C. Prentice, and N. C. Davidson, editors. The Wetland Book II: Distribution, Description and Conservation. Springer Netherlands, Dordrecht. Available from http://link.springer.com/10.1007/978-94-007-6173-5

º Ba A.D, Daddah M & Siddai, Z.A. 2018. Synthèse des connaissances sur la situation des peuplements d’oiseaux d’eau sur la zone marine et Côtière de la Mauritanie. Rapport PAZHOC/PRCM. 33p.

º Biai J. 2015. Strategy and National Action Plan for the Biodiversity 2015 - 2020. Bissau. Available from https://www.cbd.int/doc/world/gw/gw-nbsap-v2-en.pdf

º BirdLife International. 2001. Important Bird Areas in Africa and associated islands: Priority sites for conservation. Page (Fishpool LDC, Evans MI, editors)BirdLife C. Pisces Publications & Birdlife International, Newbury and Cambridge. Available from http://in-africa.org/

º Birdlife International. 2013. Conservation of Migratory Birds project : scientific review of migratory birds , their key sites and habitats in West Africa:77.

The status of waders and coastal seabirds on key natural sites of the West Africa’s coastline Bibliography 39

º BirdLife International. 2018. Global IBA Criteria- BirdLife INternational Data Zone. Available from http://www.birdlife.org/datazone/info/ibacritglob

º Brenninkmeijer A, Correia E, Monteiro H. 2015. Counting of seabird colonies and training park guards in Guinea-Bissau in 2015. Report FIBA/VEDA consultancy.

º Campredon P. 1987. La reproduction des oiseaux d’eau sur le Parc National du Banc d’Arguin (Mauritanie) en 1984/85. Alauda 55:187-210.

º Campredon, P. 2000. Between the Sahara and the Atlantic. Banc d’Arguin National Park. FIBA, La Tour du Valat, Arles, France. 110 p.

º Campredon P. 2010. Mami Wata, mère des eaux: Nature et communautés du littoral ouest- africain. Actes Sud, 220 p.

º Campredon P, Cuq F. 2001. Artisanal fishing and coastal conservation in West Africa. Journal of Coastal Conservation 7:91–100.

º Campredon P, Catry P. 2017. The Wetland Book. Bijagos archipelago, Guinea-Bissau. in C. M. Finlayson, G. R. Milton, R. C. Prentice, and N. C. Davidson, editors. The Wetland Book II: Distribution, Description and Conservation. Springer Netherlands, Dordrecht. Available from http://link.springer.com/10.1007/978-94-007-6173-5

º Catry T et al. 2017. Evidence for contrasting accumulation pattern of cadmium in relation to other elements in Senilia senilis and Tagelus adansoni from the Bijagós archipelago, Guinea- Bissau. Environmental Science and Pollution Research. Environmental Science and Pollution Research. Available from http://link.springer.com/10.1007/s11356-017-9902-8.

º Catry T, Lourenço PM, Lopes RJ, Carneiro C, Alves JA, Costa J, Rguibi-Idrissi H, Bearhop S, Piersma T, Granadeiro JP. 2016. Structure and functioning of intertidal food webs along an avian flyway: A comparative approach using stable isotopes. Functional Ecology 30:468–478.

º Coelho JP et al. 2016. Estimation of mercury background values in sediment and biota of the Bijagós archipelago, Guinea-Bissau. Marine Pollution Bulletin 111:488–492. Elsevier Ltd. Available from http://dx.doi.org/10.1016/j.marpolbul.2016.06.053

º Cosgrove, R.J. & R.W. Goff 2012. The breeding status of Royal Terns (Sterna maxima albididorsalis) in The Gambia 2012. Report WCT and DPWM, The Gambia.

º Delany S, Scott D, Dodman T, Stroud D. 2009. An atlas of wader populations in Africa and Western Eurasia. Page (Delany S, Scott D, Dodman T, Stroud D, editors). Wetlands International and International Wader Study Group, Wageningen, The Netherlands.

º Diop M.S, Diallo A.Y & P. Ndiaye, 2018. Synthèse des connaissances sur la situation des peuplements d’oiseaux d’eau au Saloum et dans la partie sénégalaise de la RBTDS. Rapport PAZHOC/PRCM. 16p.

º Dodman, T. 2014. Status, Estimates and Trends of Waterbird populatiuons in Africa: AEWA – listed African populations. Wetlands International.

º Dodman, T. et al. 1999. Les dénombrements d’oiseaux d’eau en Afrique, 1998. Wetlands International, Dakar, Sénégal.

º Dodman, T., C. Barlow, J. Sá & P. Robertson 2004. Zonas importantes para as aves na Guiné- Bissau / Important bird areas in Guinea-Bissau. Wetlands International, Dakar.

º Dodman T. & J. Sá, 2005. Monitorização de aves aquáticas no Arquipélago dos Bijagós, Guiné-Bissau. Wetlands International, Gabinete de Planificação Costeira, Dakar, Bissau.

º El Hacen, H.M., Lemrabott, S.Y. & L. Soissons, 2016. Restitution du Programme de recherche au PNBA. Rapport de symposium, Nouakchott, Mauritanie.

º Frikke, J.P & S. Asbirk. 2002. WaddenSea waders in West Africa: a survey of waterbirds in the Bijagos archipelago in Guinea-Bissau, in january-february 2001. Wadden Sea Newsletter 26: 15-17.

º Van Gils, J.A et al. 2016. Body shrinkage due to Arctic warming reduces red knot fitness in tropical wintering range. Science 352, 6287. Pp. 819-821.

The status of waders and coastal seabirds on key natural sites of the West Africa’s coastline Bibliography 40

º Hagemeijer, M. et al. 2004. Wader and waterbird census at the Banc d’Arguin, Mauritania. January 2000. WIWO report 81, 146 pp.

º Henriques, M. 2019. Knowledge on the status of waterbird populations in the Bijagos archipelago, Guinea-Bissau, with special focus on migratory shorebirds and coastal seabird colonies. Report PAZHOC/PRCM. 26p.

º Isenman, P. et al. Oiseaux de la Mauritanie

º Lourenço PM, Catry P, Lecoq M, Ramírez I, Granadeiro JP. 2013. Role of disturbance, geology and other environmental factors in determining abundance and diversity in coastal avian communities during winter. Marine Ecology Progress Series 479:223–234.

º Lourenço PM, Catry T, Piersma T, Granadeiro JP. 2016. Comparative Feeding Ecology of Shorebirds Wintering at Banc d’Arguin, Mauritania. Estuaries and Coasts 39:855–865. Estuaries and Coasts. Available from http://dx.doi.org/10.1007/s12237-015-0029-1

º Lourenço PM, Catry T, Granadeiro JP. 2017. Diet and feeding ecology of the wintering shorebird assemblage in the Bijagós archipelago, Guinea-Bissau. Journal of Sea Research 128:52–60. Elsevier. Available from https://doi.org/10.1016/j.seares.2017.08.004

º Lourenço PM, Granadeiro JP, Catry T. 2018. Low macroinvertebrate biomass suggests limited food availability for shorebird communities in intertidal areas of the Bijagós archipelago (Guinea-Bissau). Hydrobiologia 816:197–212.

º Monteiro H. 2011. Seguimento de aves aquáticas no PNO e no PNMJVP - Relatório final. Bissau, Guinea-Bissau.

º Mullié W, Camara M & A Ould Sidi Mohamed, 2015. A census of colony breeding birds in the Banc d’Arguin National Park in May 2015. Report PNBA/VEDA Consultancy.

º Mullié, W. 2016 A census of colony breeding birds on Ilot aux Oiseaux, Parc National de la Langue de Barbarie (PNLB) in May 2016. Report FIBA/VEDA consultancy.

º Naurois, R.de, 1969. Peuplements et cycles de reproduction des oiseaux de la côte occidentale d’Afrique. Mem. Mus. Nat. Hist. Nat. Nouv. Sér. A. Zoologie, 56. 312 pp.

º Oudman, T., Schekkerman, H., Kidee, A., van Roomen, M., Tentij, M. & Piersma, T. 2017. The waterbird of Parc National du Banc d’Arguin: evaluation of all complete wintercounts, workshop proceedings and na evaluation of future perspective. Report for Programme towards a Rich Wadden Sea.

º Piersma T, Lindström Å. 2004. Migrating shorebirds as integrative sentinels of global environmental change. Ibis 146:61–69.

º Salvig JC, Asbirk S, Kjeldsen JP, Palle AF, Quade A, Frikke J, Christophersen E. 1997. Coastal waders in Guinea-Bissau - aerial survey results and:33–38.

º Salvig JC, Asbirk S, Kjeldsen JP, Rasmussen PAF. 1994. Wintering waders in the Bijagos Archipelago, Guinee-Bissau 1992-1993. Ardea 82:137–142.

º Stroud DA et al. 2006. The conservation and population status of the world’s waders at the turn of the millennium In: Boere GC, Galbraith CA, Stroud DA (eds) Waterbirds around the world. The Stationery Office. Waterbirds around the world:643–648. Available from http://jncc.defra.gov.uk/PDF/pub07_waterbirds_part5.2.1.pdf

º Triplet P., Schricke V., Sylla S. & Diop I. 2009. Quel avenir pour les oiseaux d’eau dans le delta du Sénégal: situation actuelle et perspectives. OMPO, ONCFS, DPN. 69 pp.

º Trotignon, J. et al. 1980. Recensement hivernal des limicoles et autres oiseaux aquatiques sur le Banc d’Arguin (Mauritanie) (Hiver 1978 – 1979). L’Oiseau et R.F.O, 50: 323 – 343.

The status of waders and coastal seabirds on key natural sites of the West Africa’s coastline Bibliography 41

º Van Roomen, M., Nagy S., Foppen R., Dodman T., Citegetse G. & Ndiaye A. 2015. Status of coastal waterbirds populations in the East Atlantic flyway. With special attention to flyway populations making use of the Wadden Sea. Programme Rich Wadden Sea, Leeuwarden, The Netherlands. Sovon, Nijmegen, The Netherlands. Wetlands International, Wageningen, The Netherlands. BirdLide International, Cambridge, United Kingdom & Common Wadden Sea Secretariat, Wilhelmshaven, Germany.

º Veen J, Peeters J, Mullié WC, Diagana CH. 2004. Manuel pour le suivi des colonies de nidification d’oiseaux marins en Afrique de l’Ouest Manuel pour le suivi des colonies de nidification d’oiseaux marins. Wetlands International, Wageningen, The Netherlands.

º Veen J, Dallmeijer H & Cheikh Diagana 2006. Monitoring colonial nesting birds along the West African Seaboard. Report, Wetlands International, Dakar, Senegal/VEDA consultancy,

º Veen Jan & Hanneke Dallmeijer 2007. Le suivi des colonies d’oiseaux piscivores sur le Banc d’Arguin, Mauritanie (2007). Report PNBA/VEDA consultancy.

º Veen Jan, W.C. Mullié, C.M. Sylla, P. Robinson & M.S. Diop 2011. Suivi de la reproduction des colonies d’oiseaux marins 2011 de l’Ile aux Oiseaux, Parc National du Delta du Saloum. Report FIBA/VEDA consultancy.

º Veen J, Mullié W & Samb, S. 2013. Suivi de la reproduction 2013 des colonies d’oiseaux marins dans le delta du Saloum. Rapport DPN et VEDA consultancy.

º Veen J, Mullié W, Dallmeijer H, Brenninkmeijer A. 2015. Breeding distribution, numbers and diet of West African Royal Terns in 2015. Wenum Wiesel, The Netherlands.

º Wetlands International 2006. Waterbird population estimates - Fourth edition. Wetlands International, Wageningen, The Netherlands.

º Wetlands International, 2014. Annual African – Eurasian Waterbird Census National Counts Totals: 2011 – 2014. www.wetlands.org

º Wetlands international, 2015. Waterbird population Estimates. http://wpe.wetlands.org/search

º Zwarts L. 1988. Numbers and distribution of coastal waders in guinea-bissau. Ardea 76:42–55.

º Zwarts, L. et al. 1998. Wader count on the Banc d’Arguin, Mauritania in january – february 1997. Wader Study Group Bull. 86: 53 – 69.

The status of waders and coastal seabirds on key natural sites of the West Africa’s coastline

SUMMARY OF KNOWLEDGE ON THE STATUS OF WADERS AND COASTAL SEABIRDS ON KEY NATURAL SITES OF THE WEST AFRICA’S COASTLINE

With the support of