14 Devos, Melre & Kuijken:

Recent Population Estimates of Meadow-Breeding Waders in Belgium

Koen Devos, Patrick Meire & Eckhart Kuijken

Devos, K., Meire, P. & Kuijken, E. 1991. RecentPopulation Estimates of Meadow-Breeding Wadersin Belgium.Wader Study Group Bulletin 61, Supplement:14-22. This papergives the recentpopulation estimates of meadow-breedingwaders in Belgium.These estimatesare mainlybased on unpublisheddata of regionalcensuses. As mostwaders species, with the exceptionof the Lapwing,are not verynumerous and occur in well surveyedareas, we canassume that the population estimates are quiteaccurate. The most importantbreeding areas in Belgiumare indicatedin Figure 1. The currentstatus of meadow-breedingspecies in the differentregions of Belgiumis givenin Table 1 andFigure 2. In Table 2, thebreeding numbers are compared with previousestimates. The recentpopulation estimates, trends in numbersand numeric distribution are discussedspecies by species.The populationof Oystercatchersis steadilyincreasing, mainly by rangeexpansion. Black-tailedGodwits show recent increases. Whether or not this will be a continuingtrend is not yet clear.Lapwing and Curlew populations remain fairly stable.Snipe and Redshank numbers are decreasingconsiderably. Different speciesshow a markedhabitat shift. Where possiblethis is discussed. The discussiondeals mainly with the threats for breeding waders and their habitat and summarizesthe situationin Belgium. Koen Devos, Laboratoryof Animal Ecology,State UniversityGent, KL. Ledeganckstraat35, 9000 Gent, Belgium, Patrick Meire & Eckhart Kuijken, Institute of Nature Conservation, Kiewitdreef3, 3500 Hasselt,Belgium.

Introduction Belgium have been publishedregularly since 1957 (Verheyen 1957, Voet 1970, Lippens& The number of breeding waders in Belgium Wille 1972, Voet et al. 1982). is rather small in comparison to the populations in some nearby North Sea As the last estimateswere publishedalmost countries (Piersma 1986). This can be ten years ago, the aim of this paper is to explained by the small size of the country update the information on the numbers of and the fact that several speciesreach the breedingwaders in Belgium and to discuss southernlimit of their breedingrange in the the observed trends. northern part of Belgium. Despite this, severalregions in Belgium are characterized by their typical breeding populations of Materials and methods waders. Population estimates In contrastto, for example, The Netherlands and Great Britain, Belgium hasless tradition Former population estimates (Verheyen of monitoring breeding birds. Most wader 1957, Voet 1970, Lippens & Wille 1972) populationsare however restrictedto small were mainly the result of assemblingrelevant areas that are often of great importanceto regional papers (e.g. Devocht et al. 1974, nature conservation.Hence they are mostly Meeus et al. 1979, Van Gompel 1978) and covered by regional census programmes. correspondencewith local ornithologists. This makes it possibleto producereliable More recently, an atlas of breedingbirds in population estimates for most species. Belgium was published, mainly with Populationestimates of breedingwaders in information of the period 1973-1978

WSG Bulletin61, $uppl.: 14-22 (April 1991) Devos, Melre & KuiJken:Belgium 15

(Devillers et al. 1988). In 1981 a special Description of the most impor- breeding censusof waders was organizedin tant breeding areas Flanders(Voet et al. 1982).

This review is also mainly based on The most important breeding areas are unpublisheddata of regional censuseswhich indicated in Figure 1. The letters and were kindly supplied to us by the co- numbers used in this text refer to those in ordinators. The information was collected Figurel. during the breeding seasonsof 1989 and 1990. In Flanders(A), the most importantbreeding areasare the polder areasalong the coast(1) and the Schelde estuary near Assenede (2) Accuracy of the estimates and Antwerpen(3), the 'Kempen'or Campine region (4) of the provinceof Antwerp (4a, c) The accuracyof breedingcensuses improved and Limburg (4b, c) and the alluvial plainsof considerablyduring the last 50 years,mainly several rivers. because of new census methods and an increasingnumber of birdwatchers.Breeding The 'Coastal Polders' (1) is a typical numbers in the past have often been agricultural area. In the lower parts, large underestimated.Population trends are hence grassland-complexesoccur, characterizedby the combined effect of methodological a typical microrelief and in someplaces still artifactsand real populationchanges. Where seepageof brackishwater. possible,the distinctionbetween both factors is made in the speciesaccounts. Of the 'Schelde Polders', two parts can be distuingishedin Belgium. In the 'Schelde The accuracynot only varies between years Polders near Assenede' (2), large creeks but also within a year. When compiling the occur but the amount of grasslandis rather presentpopulation estimates it becameclear small. Near Antwerpen small remnantsof the that not all speciesand all breedingsites in 'Beneden Schelde Polders' (3) remain after Belgium have been censusedwith the same huge areas have been destroyed for the intensity and accuracy. However, as most expansionof the harboursince the 1960s.On wader species are not very numerous and the left bank of the fiver Schelde this fallow occur largely in well-surveyedareas, we can land has not been used for many years and assume that the estimatesgiven below are some parts have become ornithologically now close to the actualpopulation sizes. The important. The value of these areas is Lapwing Vanellus vanellus, the most however only temporary.On the fight bank abundantspecies, is howevernot countedin most of the area is industrialized. many of its breeding areas. The population size can therefore only be estimatedwith a In the 'Kempen' in the province of Antwerp large degreeof uncertainty. ('Antwerpse Kempen', 4a) and Limburg ('Limburgse Kempen', 4b) very important Netherlands

North Figure 1. Map of Belgium showingthe different regions of major importance for wadersbreeding on meadows: A Flanders 1. Coastal Polders;

ß 2. Schelde Polders near Assenede; 3. Beneden Schelde Polders; 4. 'Kempen', 4a. AntwerpseKempen; 4b. LimburgseKempen; 4c. Zuiderkempen; 5. Other areasin Flanders; • B Southernpart of Belgium. WSG Bulletin 61, Suppl.: 14-22 (April 1991) 16 Devos, Meire & Kuijken: Belgium breeding areas of meadow birds occur. The southern part of the 'Kempen', the 'Zuiderkempen'(4c), is of minor importance. The former very extensive 'Kempische' moorlandshave largely been cultivated and are now restrictedto some relatively small areas. As the moorlands disappeared,most wader speciesmoved to the grasslandareas which now occur all over the area.Gradually, however, these are now being changed to arable land.

Outside these areasmost breedingwaders are found in the alluvial plains of the river Schelde and its tributaries (5) and in the valley of the river Maas.

In the southernpart of Belgium (B), with the * 0-5 exceptionof the Lapwing, very few breeding ß 6 - 2.5 waders occur. Most breeding is restrictedto • 26 - 100 the 'Condroz','Fagne' and 'Famenne'as well ß 101 - 200 as in the valley of the Haine. 201- 400 I > 400

Species accounts Figure 2. Numeric distribution of Oystercatcher Haernatopusostralegus, Snipe Gallinago gallinago, Black-tailed Godwit Limosa limosa, Curlew Nu- The breedingnumbers for the different parts menius arquata and Redshank Tringa totanusin of Belgium are given in Table 1 andFigure 2. Belgium, 1990. A summaryof the populationestimates since the middle of the 1950s is shown in Table 2. Oystercatcher Haematopus ostralegus As already mentioned,some of thesefigures have to be interpreted with care. Therefore The currentpopulation size can be estimated the results will be discussedspecies by at 610-640 pairs.It is a ratherwidespread and species. non-colonialspecies and thereforesometimes

Table 1. Numbers of meadow-breedingwaders in different regions in Belgium in 1990.

regions(see. Fig. 1) 1 2 3 4a 4b,c 5 B

Oystercatcher 175-195 30 150 >130 48-53 >80 0

Lapwing + + 800 >3,000 + + 5,000-6,500

Snipe 0 0 0 0 30-35 0-3 15-25

Curlew 0 0 4 250-265 185-205 0 0

Black-tailed Godwit 272-285 2 100-105 400420 78-87 12-15 0

Redshank 59 04 85-90 2-5 0-2 0 0

WSG Bulletin61, Suppl.: 14-22 (April 1991) Devos, Melre & Kuljken:Belgium 17

Table 2. Numbers of breedingpairs of meadow-breedingwader speciesin Belgium: summary of the available data.

years 1956 1968 1972 1977 1981 1990

Oystercatcher 16-20 65 60 170-175 380 610-640

Lapwing 1,300-1,500 >4,000 5,000 + > 15,000 +

Snipe >60 45 80 + 115-130 45-65

Curlew 230-270 300-310 350 380-385 475 440-475

Black-tailed Godwit 150 225-235 240 >400 750-780 865-910

Redshank 160 180-190 190 190 210 145-160

Sources:1956- Verheyen1957; 1968- Voet 1970; 1972- Lippens& Wille 1972; 1981- Voetetal. 1982; 1990 - thispaper. +: not surveyed. difficult to countprecisely. However, as this the population in Limburg has doubled. In speciesis not very numerousand it is very the 'Beneden Schelde Polders', numbers conspiciouswe can assumethis estimate to increasedfrom 89 pairs in 1981 to 150 in be quite accurate. 1990. The speciesis also still expandingits breedingrange to the south,with a preference The increaseof the populationas illustrated for cultivatedland in river valleys. in Table 2 is largely a real one. Originally the Oystercatcherwas a rare breeding bird in In the most important breeding areas, the Belgium (< 20 pairs), restricted to some species prefers to breed on arable land coastal sites. Since the middle of the 1950s, (maize). The presence of nearby (wet) numbersincreased and the distributionrange meadows is however essential as the birds extendedrapidly. The colonizationof inland use theseas feedingareas. habitatswas very, successfuland the species is now widespreadin the northern part of Belgium. This expansionseems to be still Lapwing Vanellus vanellus continuing. We are not able to give a recent estimate of The largestbreeding numbers in Belgium are the Belgian breeding population. In most found in the Coastal Polders: 175-195 pairs regions,this abundantspecies is not covered in 1990. Some 30-40 yearsago, the 'Zwin' at by census programmes. A rather detailed Knokke-Heist and the 'IJzermonding' at census in 1981 revealed a population of Nieuwpoortwere the only breedingplaces in 15,000-20,000pairs for Belgium. the Coastal Polders. Now with 31 and 3-5 pairs respectively,they hold only a minor Some local monitoring programmes show part of the population.In thesecoastal sites, that the breeding numbers have been numbershave not changedmuch since 1960. relatively stable during the last 10 years It is the spreadinland during the last decades (Devos, unpublisheddata; and pers. comm. that causedthe coastalpopulation to increase. local co-ordinators).

In other regions, the same developmenthas The Lapwing was originally a breedingbird been apparent.Since 1981, a 30 % increase of grasslands.However, in many areas, was noticedin the "AntwerpseKempen" and especiallyreallotment areas, there is often a

WSG Bulletin61, Suppl.: 14-22 (April 1991) 18 Devos, Meire & Kuijken:Belgium decrease in the surface of permanent during the late 1970s. In the valley of the grassland.The speciesseems to adaptto this river Schelde (3-5 pairs in 1981) and in the loss of old, wet pasturesby the colonization 'AntwerpseKempen' (7 pairs in 1981), the of arable land. Snipebecame an irregularbreeder.

Lapwings are widespread.Most birds occur in the northernpart of the country,especially Curlew Numenius arquata in the CoastalPolders (> 2,000-2,500 pairs) and in the 'Antwerpse Kempen' (> 3,000 In 1989, all breeding places were censused pairs). During the last decades,there was a quite well and the populationcan now be markedexpansion during which the southern estimatedat 440-475 pairs, a little less than part of Belgium was colonized(5,000-6,500 the 475 pairsin 1981 (Table2). The breeding pairs). population is now probably quite stable. Table 2 shows a gradual increasesince the middle of the 1950s until 1981. It is not Ruff Philomachuspugnax certain, however, that this reflects a real populationgrowth; numbershave probably Until the middle of this century, a small beenunderestimated in the past. population occurred in the large and wet moorlandsof the 'AntwerpseKernpen'. In the Breeding Curlew are almost entirely period 1950-1980 the Ruff became a very restrictedto the 'Kernpen'.In the 'Antwerpse rare (maximum2 pairs) andirregular breeder, Kempen', 250-265 pairs were counted in mainly in the Polder areas. As far as we 1989. At least 185-205 pairs are breedingin know, no breeding attempts have been the 'LimburgseKernpen'. observedduring the last ten years. In both regions, there have been obvious changesin both distributionand breeding Snipe Gallinago gallinago habitat, mainly as a consequence of landscapeand agriculturalalterations. In the The total of only 45 to 65 pairs in 1990 past, the species was restricted to heather makes the Snipe one of the rarest meadow- moorswith fens and wet depressions.During breedingwader speciesin Belgium. Table 2 the last decades, extensive areas of this indicates the considerable decrease which has habitat type have been changed into taken place since 1981 (115-130 pairs). agricultural land. However, decreases in Numberswere always underestimatedbefore Curlew numbersdue to the disappearanceof the census in 1981, so we are probably moorlandswere offset by shiftsto cultivated dealing with a long term decrease that is land. A considerable part of the Belgian already going on for decades.Numbers in population is now breeding on meadows. 1990 were extremely low due to the very dry This adaptationto grasslandhas led to the summer season. colonizationof a new region in 1987: the 'Beneden Schelde Polders', where 4 pairs The species'range has contractedalmost were counted in 1990. entirely to the eastern part of Belgium. In Limburg, the breeding population is estimatedat 30 to 35 pairs. In the southern Black-tailed Godwit Limosa limosa part of Belgiumthere is a smalland declining population,fluctuating around 15-25 pairs. The total Belgian populationreached about 810 - 860 pairsin 1989 and 865 - 910 pairsin Habitat loss, mainly through extensive 1990. These numbers are quite accurate drainage and agricultural improvement becauseall breedingareas were well covered. projects, has caused the extinction of the speciesin many other areas.In the Coastal The population gradually increased after Polders,particularly in the floodplains of the 1950, although breeding numbers have fiver IJzer, the last breedingbirds were seen probably been underestimateduntil 1981

WSG Bulletin 61, Suppl.: 14-22 (April 1991) Devos, Melre & KulJken:Belgium 19

(Table 2). In 1981, the total number of underestimate is almost certain. Therefore breeding pairs was about 750 pairs. The this declineis probably a long term trend. breeding population remained relatively stableduring the following years,but in 1989 The decline of Redshank numbers has been and 1990 numberswere considerablyhigher, noticed simultaneouslyat all breedingsites. an increasewhich was not seenin all regions. In some areasthis speciesseems to be on the verge of extinction. As the species is The 'Antwerpse Kempen' which holds most concentratedin very few areasthe population breeding Black-tailed Godwits, has a is very vulnerablefor further habitatloss. population that fluctuates around 400-420 pairs (1987-1990). No recent increase has Two main breeding 'areas can be occurred. The census in 1981 revealed more distinguished.One is in the North-Eastern than 500 pairs but that was an exceptional part of the CoastalPolders. A detailedsurvey year. The speciesis somewhatless numerous in 1982 revealed 84 to 86 pairs (Desmet in the adjacent 'LimburgseKempen': 78-87 1985). In 1990 only 59 pairs were counted.In pairs in 1989. This numberis slightly higher this Polder area, the Redshankis stronglytied thanin previousyears (60-70 pairs). to the brackish habitats on clay soils. Microrelief, ditches that are silted up, More to the West, the Coastal Polders also watering places for cattle and other muddy hold a considerable part of the Belgiari spots are most attractive for this species population. Recent censusesrevealed the (Desmet 1985). This habitat type is following numbers: 185-190 pairs in 1988, disappearingrapidly as a consequenceof 210-220 pairs in 1989 and 272-285 pairs in changedagricultural practices. The speciesis 1990 which was the highest number ever very sensitive to drainage and pasture recorded.The recent increaseof the Belgian improvements.In addition, one of the most total populationcan clearly be ascribedto the importantbreeding places (20 pairs in 1982, trend in the CoastalPolders. No explanation 31 in 1990) is gradually disappearingdue to for this recent increase is available. In the the expansionof the harbour of Zeebrugge. past, the species was mainly restricted to This site will be lost completely in the near large areas of wet hay meadows.These are, future. however, disappearingquickly. The Black- tailed Godwit seemsto adapt quite well to In the 'Beneden Schelde Polders', the decline this evolution;in many areasthere is a shift was less dramatic.A total of 94-97 pairs in to grazingmeadows. 1981 was reduced to 85-90 pairs in 1990. Here the expansion of the harbour of Antwerp hasled to the disappearanceof large Redshank Tringa totanus wet grasslandareas. It has to be stressedthat more than half of the populationin Belgium In 1989-1990, the population size was is now breedingon temporarygrounds. probably not higher than 145-160 pairs. As the speciesis not very widespreadand not In the 'Schelde Polders near Assenede', a very common, this estimateis thoughtto be progressivedecline in numbershas already quite exact. It is the lowest breedingnumber resultedin irregularbreeding of the speciesin ever recorded. It has to be mentioned that that area: 29-30 pairs in 1968, 5-10 pairs in 1989 and 1990 were both dry summer 1981, 0-4 pairsin 1990. seasons,which proved to have a negative effect on breeding Redshanks(Van Gompel In the 'Kempen'in the provinceof Antwerpen 1988). In wet breeding seasons,breeding and Limburg, numbersfell from 18-19 pairs numbersmight probablybe slightlyhigher. in 1981 to 2-7 pairs in 1990.

It is clear, however, that a considerable decline has occuredsince 1981 (210 pairs). Discussion Earlier estimates during the period 1955- 1977 were somewhatbelow 200 pairs,but an As mentioned in the introduction the number

WSG Bulletin 61, Suppl.: 14-22 (April 1991) 20 Devos, Meire & Kuljken:Belgium of most meadow-breedingwader speciesin major qualitative threats. As a result of all Belgium is very small indeed. This is these factors, interest has increased in the confumedby Table 3 in which our estimates remaining less cultivated semi-naturalareas are compared to the population estimates in an attemptto compensatefor the losses. given by Van Dijk et al. (1989) for Europe Here the effects of modern agricultural and the nearby arctic (excl. USSR). In an improvementcause even more conflictswith international context, our country is most conservationistthan in traditionalproductive importantfor breedingLapwings. About 2% areas. The following stagesillustrate how of the populationare estimatedto breed in these semi-natural, ecologically very Belgium. Very little information on this important grasslandswhich are the key speciesis availablehowever. breeding areas for meadow birds are threatened: On a national scale the other speciesare much more important, especially because lowering the water level in valleys and their declineis linked to the disappearenceof polder depressions:building pumping a specific habitat, this applies to Redshank stations,straightening of rivers, rivulets and Snipe. Other speciessuch as the Curlew and brooks, creation of artificial water showed a clear habitat shift from moorlands reservoirsfor stockingwater "surplus"to to grasslands,but as these are now also avoid larger inundations (mainly in disappearing,the futureis uncertain. winter);

The loss of habitat is a crucial problem for - on these drained soils, earlier access in severalspecies of meadow breedingbirds. In springwith heaviermachines is possible, the last few decades,agriculture has had to enabling earlier and increased use of give up a large areaof highlyproductive land fertilizer (plus use of herbicides).After for urban and industrial expansion. In only one seasonthere is a drasticdecline Belgium 265,000 ha were lost to building in the original diversity of the plant development between 1960 and 1984, of community, with several sensitiveplant which 60% were in Flanders.The expansion speciesdisappearing; of the harboursin Zeebruggeand Antwerpen have been, for example,responsible for the - old permanent grasslands (especially lossof importantwader breedingareas. hayfields)are then ploughedand reseeded with highly productivemixtures of grass Besides these spatial threats, pollution, species and even more fertilizers are acidification, eutrophication,over-use of added; fertilzers and disturbanceof water supplyare

Table 3. Proportionsof the Belgianbreeding wader populationsin the total of Europe (excl. USSR) and the nearby arctic as estimatedby van Dijk et al. (1989). For Belgium,maximum estimatesare used.

species Belgium Europe % in Belgium

Oystercatcher 640 209,000-245,000 0.3%

Lapwing 20,000 923,000-994,000 2.0%-2.2%

Snipe 65 530,000-539,000 <0.1%

Curlew 475 122,000-128,000 0.4%

Black-tailed Godwit 910 94,700-119,000 0.8%- 1.0%

Redshank 160 164,000-172,000 <0.1%

WSG Bulletin61, $uppl.: 14-22 (April 1991) Devos, Meire & KuiJken:Belgium 21

as a result of decreasedflooding, better is less harmful for breeding waders, drainage and nutrient input, earlier and following examplesin e.g. The Netherlands more frequent mowing (silage grass) and Germany. In 1990, a private nature becomes a general practice: this causes conservationorganization also boughta first conflict with breeding birds and gives reserve of special interest for meadow plant speciesno chanceto seed: the most breedingwaders in the Coastal Polders.This sensitivespecies only survivein the field is at presentthe only meadow bird reservein marginsand alongditches; Belgium.

due to the Europeanmilk quotasmore and The protection of these wet meadows is not more grasslandsare irreversiblychanged only importantfor the breedingbirds. On an into arable fields (between 1977 and 1984 internationalscale the numbersbreeding in 3,570 ha of grasslandsdisappeared each Belgium may be very small indeed, but on year in Belgium!); besidesthe traditional migration these breeding areas are used by cropof potatoes,maize cropsare preferred very largenumbers of migratingbirds. at present,because of the high amountof animal dung that can be dumpedhere (a surplus available from intensive bio- Acknowledgements industries); This paper relies heavily on information as a result, a tremendous over-fertilization provided by A. Anselin, L. Benoy, F. De has occurred during the last ten years, Scheemaeker, W. De Smet, J. GabriEls, J.P. notablyin the northernand westernpart of Jacob,P. Lingier, P. Maes, J. Rutten, J. Van Flanders;this causesmany negative side Impe who centralizedthe information of the effects even in the best protected nature different areas. Many other people reserves (ruderalization); furthermore, participated in the censuses.Without their sportfisheries and catchmentof drinking- help we could not have prepared these new water became quite impossible(Kuijken populationestimates. 1988).

Most of these developmentsform part of References reallotments and hydraulic improvement plans, which still aim at increased Desmet, J. 1985. Voorkomen en ecologie van de Tureluur Tringa totanus als broedvogel in de productivity. In the context of the European Westvlaamse Oostkust. Wielewaal 51:444-451. Community's agricultural surpluses, it is Devillers, P., Roggeman,W.,Tricot, J., del Martool, debatable whether the subsidies concerned P., Kerwijn, C., Jacob, J.-P. & Anselin, A. (eds.) are still justified. It would be morerewarding 1988. Atlas van de Belgische Broedvogels. to extend EC subsidiesfor farming in areas Brussel, Koninklijk Belgisch Instituut voor with a naturalhandicap to the last inundable Natuurwetenschappen. Devocht, J., Paulussen, W. & Pinceel, L. 1974. valleys. In 1960, flooded areas in Flanders Inventads der broedparen van Gruuo, Wulp, covered 35,000 ha; this has been reduced to Tureluuren Scholeksterin de TurnhoutseKernpen. less than 10 percent of that area in 1987 Wielewaa140: 8-14. (Kuijken 1988). There are, however, some Kuijken, E. 1988. Applied ecologicalresearch on the positive developments. Under the EC conservationof wet grasslandsin relation to Directive on the conservation of wild birds, agricultural land use in Flanders (Belgium). In Park J.R. (F_xl).Environmental Management in over 100,000 ha have been designatedas agriculture. European Perspectives. Belhaven specialprotection areas in Flanders,much of Press,London. which is semi-naturalgrassland, and covering Lippens, L. & Wille, H. 1972.Atlas van de vogelsin most of the importantmeadow bird breeding Belgigen West-Europa.Tielt, Lannoo. sites. Hopefully this will result in a better Maes, P., Meeus, H. & Voet, H. 1985. Broedvogels in Vlaanderen, 1980-1982. Wielewaal 51: 185- protection.In 1991, the Flemish government 202. will startsome pilot projectsin theseEC Bird Meeus, H., Berckvens, L. & Leestmans, L. 1979. Directive areas in which farmers will receive Inventads 1978 van de broedparenvan Grutto financialsupport for farmingin a mannerthat (Limosa limosa), Wulp (Numenius arquata),

WSG Bulletin 61, Suppl.: 14-22 (April 1991)