Diet Selection of Lesser White-Fronted Geese Anser Erythropus at a Spring Staging Area

ECOGRAPHY 26: 705–714, 2003

Diet selection of lesser white-fronted geese Anser erythropus at a spring staging area

Juha Markkola, Marika Niemela¨ and Seppo Rytko¨nen

Markkola, J., Niemela¨, M. and Rytko¨nen S. 2003. Diet selection of lesser white- fronted geese Anser erythropus at a spring staging area. – Ecography 26: 705–714.

We studied diet selection of the globally threatened lesser white-fronted goose Anser eythropus at a spring staging area on the island of Hailuoto (64°00%N, 24°45%E), off the western coast of Finland. We determined the diet using droppings, which were collected in late May, when the geese had left the area and migrated northwards. The sample potentially comprised of ejecta from 31 different individuals. Plant identification was based on visual determination of epidermal fragments. A total of 100 droppings were sampled using a point quadrat method. We calculated the percentage of each identified taxon in each dropping and related this to the availability of the corresponding taxon in the meadow. We measured preference for each taxon using o Chesson’s electivity index ( i) and tested them by bootstrap resampling. The diet contained 9 taxa of the ca 40 available. Almost all dietary items were Monocotyle- dons (99.9%), mostly grasses (88.7%) including Festuca rubra (43%), Phragmites australis (30%) and Calamagrostis stricta (13%). Only Phragmites (o=0.73, p= 0.000), Festuca (o=0.52, p=0.004) and possibly Triglochin palustris (o=0.70, p= 0.125) were preferred, all other species were avoided. All preferred species were quite common and other goose species exploit them too. The lesser white-fronted geese preferred large natural meadows that were five times broader than an ‘‘average’’ Bothnian Bay meadow. All forms of mowing and grazing management benefit the restoration of lesser white-fronted goose habitats at the landscape level. Festuca and especially Triglochin benefit from such management. Reeds, Phragmites, whose spread has been the main cause of coastal meadow deterioration, can be controlled by management, but can also be maintained among other vegetation if mowing is less frequent or grazing not too intensive.

J. Markkola ( juha.markkola@oulu.ﬁ), M. Niemela¨, and S. Rytko¨nen, Dept of Biology, Uni6. of Oulu, P.O. Box 3000, FIN-90014 Oulun yliopisto, Finland.

The lesser white-fronted goose (abbreviated later as is on the verge of extinction, comprising B50 breeding LWfG) Anser erythropus L. was a numerous breeding pairs (e.g. Aarvak et al. 2001). bird species in arctic and sub-arctic areas between Beginning from Nordic initiatives in the 1970s and Scandinavia and the Far East before World War II 1980s a network of conservation activities was estab- (Lorentsen et al. 1999). In recent decades, population lished step by step throughout the entire distribution numbers have fallen and the distribution range has area of the LWfG from Europe to China and the Far contracted drastically (Norderhaug and Norderhaug East. The LWfG Task Force was established under the 1984). The most serious threat, based on results of Goose Specialist Group of Wetlands International in ringing and satellite telemetry studies, is illegal or, in 1994. An action plan to protect the LWfG was ap- some countries, legal hunting (Tolvanen and Markkola proved by the European Council and published by 1998). At present, the autumn population comprises BirdLife International (Madsen 1996). little over 25 000 individuals, and the species is globally Results from a range of studies are required to threatened. In Nordic countries the LWfG population construct a basis for undertaking a comprehensive vul-

ECOGRAPHY 26:6 (2003) 705 nerability analysis (Soule´ 1986), necessary for successful (L.) and Carex mackenziei (V. Krecz.). Juncus gerardii formulation of conservation policy. The conservation (Loisel.) and Calamagrostis stricta (Timm, Koeler) are biology studies of recent years have included analysis of common throughout the whole meadow. Upper parts population trends and distribution (e.g. Iwabuchi et al. of the meadow are characterised by Festuca rubra and 1997), migration routes (e.g. Lorentsen et al. 1998) and locally with willow shrubs. Minor variation in topogra- population genetics (Ruokonen 2001) of the LWfG. phy breaks zoning by creating mosaic like vegetation. One fundamental need is an understanding of the diet Phragmites and Carex mackenziei typically grow in and habitat selection in staging areas. In particular, can most shallow depressions and Festuca on low hillocks. an understanding of these be of benefit to the LWfG in Since 1986, To¨mppa¨ meadow has been managed by these areas? Depending on the migration patterns and mowing, successfully reducing the previously expanding phenology of a particular bird species, conditions on reed beds and areas of willow scrub. the wintering quarters, in spring-staging places and in The area lies within the mid-boreal coniferous forest breeding areas contribute to varying degrees to the zone and is subject to compensatory land-uplift of ca 8 ultimate reproductive success of a population (e.g. mm per year (Siira 1970). The area is scheduled under Nilsson 1979). In northern breeding, long-distance mi- the National Conservation Programme of Wetlands in grating geese as the LWfG, the feeding conditions at Finland, confirmed by the Council of State in 1982, and stop-over sites are important (Ebbinge et al. 1982, Prop it has been included in Project Mar, as a proposed and Deerenberg 1991). The female geese acquire energy Ramsar wetland of international importance and pro- stores in spring-staging areas before moving to the posed Natura 2000 site. The LWfG working team of breeding places, where very little food is available dur- WWF Finland annually carries out observation work at ing the egg laying period. To¨mppa¨ during the entire spring staging period of the This study aimed to reveal diet and habitat prefer- LWfG as a part of the annual monitoring and research ences of the LWfG on the Bothnian Bay coast during program. spring staging. The results were applied to recommendations for management planning of the coastal meadows along the Bothnian Bay, with particular emphasis Habitat quality on recommendations for management of mowing or grazing. Our working hypothesis was that LWfG staging along the Bothnian Bay prefer the most extensive coastal meadows. To test this the 9 meadows used by LWfG during the last 10 yr were compared with 20 randomly Material and methods sampled meadows throughout the Bothnian Bay coast % % Study area between Kalajoki, 64°15 N and Kuivaniemi 65°30 N. Latitude and longitude co-ordinates of 20 points Diet selection of the lesser white-fronted goose was were randomised and the nearest meadow to each was studied on coastal meadows at To¨mppa¨ on the island of included in the sample. The width of the meadow was Hailuoto (64°00%N, 24°45%E), on the Finnish western measured from 1:20 000 National Survey Board maps coast of the Bothnian Bay. During 1985–2002 this (1980s edition) between the wooded zone to the land- meadow supported, in most years, the majority of all ward side and the shoreline. Under conditions prevail- lesser white-fronted geese using the Bothnian Bay ing throughout the Bothnian Bay this equates to the flyway from the border area between Greece and geolittoral zone situated between the average sea level Turkey via Hungary and Estonia towards Lapland and and the high water level (Siira 1970). The hydrolittoral Finnmark, in northern Norway (Aarvak et al. 1999). In zone between the (average) sea level and the lowest 1985–1988 the Bothnian Bay meadows hosted ca 100 water level was roughly measured determining the dis- LWfG. After that the numbers declined and in 1993, tance between the shoreline and the dotted line on the when the dropping samples were collected, 31 LWfG maps showing ca minus one metre under the average used the meadow of To¨mppa¨, out of all 33 staging on sea level. The difference in the width of the geolittoral the Bothnian Bay coast. In 1994 the total number was and hydrolittoral zones was T-tested (one tail, unequal 46 but declined gradually to ca 25 in 2000 (Markkola variances) between LWfG staging places and the refer- 2001). The Valdak marshes in Finnmark, N Norway ence meadows. unite more branches of migration routes and therefore host more LWfG, e.g. 84 individuals in spring 1998. The central, relatively uniform part of the meadow is Determining diet ca 1 km2 and is flanked by extensive mud-flats and shallows, the area of which varies greatly according to The easiest method of studying diet is to determine the the sea water level. Vegetation near the shoreline is contents of the digestive system in dead birds. Sedinger dominated by Eleocharis species, Agrostis stolonifera and Raveling (1984) applied this method in Canada

706 ECOGRAPHY 26:6 (2003) goose Branta canadensis L., Budeau et al. (1991) in droppings and logged these according to species or white-fronted goose Anser albifrons Scopoli and Ster- taxon and the type of tissue concerned. We sampled the betz (1978) in Hungary in the white-fronted goose and points determining their location as pairs of numbers even in the LWfG. This method enables identification taken from the random number table and using these of plant material freshly consumed but requires destruc- figures as co-ordinates (x,y) of the movable objective tive sampling – i.e. killing the birds. table of the microscope. Leaves and leaf sheath epider- An alternative method useful in threatened species mis tissues were differentiated as upper and lower epi- involves study of the diet by determination of frag- dermis, enabling identification of one or both in any ments of plant epidermal tissues in faecal pellets. This one fragment. Where only one epidermis layer was method was originally developed and tested by Stewart detected, this was noted with details of which side was (1967), studying mammal grazers in East Africa. Owen involved. In all, 2000 observations were made, 20 from (1975) tested the applicability of the method in geese, each dropping. and it was also discussed in detail by Bhadresa (1986). Mechanical damage may cause leaf fragments to The faecal method has been widely applied in diet have both or only one of the lower and the upper selection studies in e.g. pink-footed Anser brachy- epidermis present. Thus overestimation of leaf frag- rhynchus Baillon, white-fronted and Canada goose, ments of less robust species might occur if all epidermal brent Branta bernicla L. and barnacle goose Branta fragments were simply summed and compared. Some leucopsis Berchstein (Owen 1976, Buchsbaum et al. structural features in the epidermal cells of a number of 1986, Madsen and Mortensen 1987, Prop and Deeren- species complicate identification. For example Festuca berg 1991, Spilling et al. 1994). rubra and Calamagrostis stricta can only be separated We collected 200 droppings in late May after the by the lower epidermis. Epidermis on both leaf sides is LWfG had continued their migration northwards. They very similar in Agrostis-species (A. stolonifera, A. were dried at room temperature and ground for micro- gigantea Roth) and they were totally inseparable from scopic examination. In the field it was not possible to each other, in addition, if only one epidermal side was determine droppings from different LWfG individuals, present, separation from upper epidermis of many other thus the sample is more or less a random sample of all Poaceae was impossible. Variation of robustness to LWfG droppings at To¨mppa¨ meadow. The sample physical damage and the close similarity in upper epi- potentially contained droppings of up to 31 LWfG individuals. In addition to LWfG, the meadow is used dermal patterns of most grasses, resulted in calculations by greylag geese Anser anser anser L. and to a lesser of relative proportions of grass items being based upon extent bean geese Anser fabalis fabalis Latham, but the the number of fragments of lower epidermis only. faecal pellets of the LWfG can be easily discriminated In addition we corrected the figures of plants avail- because they are ca 30% thinner and shorter than the able and used (Table 2) to get data sets compatible. droppings of the larger species. Some diet classes had to be removed and some species To enable identification of different plant species in in the meadow data had to be clumped (e.g. sedges to droppings, we collected specimens of all the 48 vascular form a collective class of Carex spp.). Categories plant species available at To¨mppa¨ meadow after the Eleocharis/Juncus, monocotyledonous and unidentified LWfG had left the area in spring 1993 and in some plants were deleted. Poaceae items with only the upper other parts of the Hailuoto Island in November 1994, epidermis, not recognizable at the species level, in- when the plants were practically in the same condition cluded Agrostis leaf fragments, which had only one as in spring. Epidermal tissues – which are the most epidermal side. The number of Agrostis items lost into effective to differentiate between plant species – of Poaceae was estimated using Owen’s (1975) counts, different parts of the plants were prepared for reference which showed that in white-fronted goose droppings samples using the method of Metcalfe (1960) without the proportion of Agrostis items holding both layers of the use of staining. Reference samples were pho- epidermis – in our case 9 items – was 43%. Calama- tographed using a microscope–camera combination grostis/Festuca lower epidermis category was divided (Fig. 1). Plant epidermal fragments in goose droppings between the taxa using the proportion gained according were compared with the reference samples. to confirmed observations of these species. These cor- We sampled 100 of the 200 dried droppings and rections were made to every dropping and every vegeta- ground them manually to avoid excessive destruction of tion plot. tissues. Then we mixed the sample carefully and one tenth sub-sample was diluted in 70% ethanol and left for some hours. After incubation, a 1/5 sub-sample was Availability transferred to glycerine on a slide. Following Owen’s (1975) instructions the sample was spread evenly under Availability of potential dietary plant species was as- the cover glass. Using the point-quadrat method (Owen sessed by estimating percent coverage of all plant spe- 1975, Bhadresa 1986) we identified plant fragments in cies in 169 random 1 m2 vegetation plots of the

ECOGRAPHY 26:6 (2003) 707 Fig. 1. Light microscope photos of epidermal tissues of the reference material: leaf under side epidermis of (a) Festuca rubra (×227), (b) Phragmites australis (×231), (c) Calamagrotis stricta (×221), (d) Triglochin palustris (×215). meadow area. This was done in June and July when r 1 a = i plant identification was easy. The scale used was +, i m ni % 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 15, 20, 25, 30, 40, 50, 60, (rj/nj) j=1 70, 75, 80, 85, 90, 95, 97, 98, 99, 100%. To assess food a selection and preference, we modified the percentage where i =Manly’s selection index for dietary type (e.g. cover values to the percentage of the total plant cover a plant species) i, ri,rj =proportions of dietary type i (leaving bare soil and litter away), for each species in and j in the diet (i and j=1, 2, 3,…, m), ni,nj =propor- each vegetation plot. tion of dietary type i and j available, m=number of potential dietary types. Manly’s alpha is applicable in situations where the Preference and diet selection prey (diet plant) population can be assumed not to be significantly depleted by feeding activity (Krebs 1989). The geese prefer some plant species and may avoid In this study we considered that LWfG exploit a very others (e.g. Owen 1976, Sedinger and Raveling 1984, small proportion of the food available, the quantity of Madsen and Mortensen 1987, Prop and Deerenberg which remains stable. To obtain results that are com- 1991). The preference for a species can be assessed by parable between cases, where the number of available comparing the proportion of the species in the diet with dietary types varies, we converted Manly’s alpha to the proportion of the species available in vegetation as electivity index presented by Chesson (1983): food (Krebs 1989). We measured diet selection by the o a LWfG using the electivity index ( ) presented by Ches- o m i-1 son (1983). It is based on Manly’s alpha selection index i = a (m-2) i +1 (a) that has been widely applicable in diet studies (Krebs 1989). Using Manly’s alpha it is possible to rank Chesson’s electivity index potentially ranges between plants in order according to frequency in the diet. −1and+1. Dietary types having negative values are

708 ECOGRAPHY 26:6 (2003) Table 1. Comparison in meadow width between lesser white-fronted goose meadows (n=9) and a random sample of Bothnian Bay meadows (n=20).

Geolittoral Hydrolittoral

mean min max mean min max

LWfG meadows 960 3401300 978 600 2000 Reference meadows 176 10 860 375 10 1500 avoided (or selected at levels below that expected on the grostis stricta (13.4%). The most commonly used of basis of availability) and types getting positive values other Monocotyledons was Juncus gerardii (8.4%). All are preferred (Chesson 1983). If the index value is zero, these species were common on To¨mppa¨ meadows and the food item concerned is taken in the same propor- on the coastal meadows in general, and the LWfG is tion as it is available. thus not dependent on any rare plant species. The results revealed two new plant taxa in the diet of the LWfG: Phragmites (a grass) and Eleocharis spp. (other Testing the reliability of electivity indices monocotoledonous plants). Indeed, P. australis was the most preferred species. We tested the reliability of electivity indices using the Plant species composition in single droppings pro- bootstrap method (Dixon 1993, Efron and Tibshirani vides information on diet selection in short intervals o 1993). The original i-values were resampled without and about variation in diet selection. Of 100 analysed replacement 1000 times, and an empirical p-value for droppings, 22 consisted exclusively of P. australis and the preference test was achieved by counting the pro- 18 of Festuca rubra. The rest were multi-species in portion of p-values that were on the other side of the content. Their distribution according to the main spe- boundary of neutral selection (o=0) than the original cies was (the average dominance of the main species in o i-value. parentheses) Festuca rubra 30 droppings (67.9%), Cala- magrostis stricta 13 (65.2%), Phragmites 7 (81.2%), Juncus gerardii 6 (54.8%), Triglochin palustris (L.) 2 Results (61.9%) and Agrostis sp. 1 (66.7%). LWfG preferred extensive meadows (Table 1). The Table 2. Diet used by the lesser white-fronted goose – original average width of the meadow geolittoral favoured by and revised data – and the diet plants available on To¨mppa¨ meadow of the isle of Hailuoto, W Finland. Figures are based LWfG was 960 m compared to 176 m among the on 100 droppings and 169 vegetation sample plots of 1 m2. reference meadows (T-test, one-tailed, unequal variances, t=3.548, DF=27, pB0.0001). The hydrolit- used (%) Available (%) toral zone showed the same pattern (Table 1). This zone, however, reflects more the condition of future Original corrected meadows resulting from isostatic up-lift than the situa- res. tion at present. The average width of the hydrolittoral Poaceae zone at LWfG meadows was 978 m compared to 375 m Festuca rubra 17.3 43.1 9.2 in the reference points (T-test, one-tailed, unequal vari- Calamagrostis stricta 4.2 13.4 19.9 ances, t=2.810, DF=27, pB0.01). Festuca/Calamagrostis 12.8 – – Phragmites australis 18.9 30.2 3.9 Table 2 shows the original (n=2000) and final (cor- Agrostis sp. 0.4 1.9 11.1 rected) (n=1069) results of dietary items and plants Poaceae spp. 12.6 –– available. About 24% of items could not be identified Rushes and Cyperaceae (e.g. non-epidermal fragments, humus colloids or ob- Juncus gerardii 4.5 8.4 17.4 scure conglomerations). After corrections, the number Eleocharis sp. 0.05 0.07 8.4 Eleocharis/Juncus 0.05 –– of observations per dropping declined to 1–19, with the Carex sp. 0.5 1.3 11.8 average of 10.7. Eriophorum angustifolium ––0.6 The results showed that the diet of the LWfG con- Other Monocotyledonae sists nearly exclusively of monocotyledonous plants. Of Triglochin palustris 0.3 1.2 0.2 Triglochin maritima – – 0.2 all 1524 determined fragments, 99.9% were Mono- Potamogeton sp.– – 0.1 cotyledons of which 87.1% were grasses. The correc- Monocotyledonae 4.3 –– tions did not radically affect proportions: 99.8% for Dicotyledonae 0.1 0.2 17.2 Monocotyledons and 88.7% for grasses. The three most Unidentified 23.8 –– Total (%) 100 100 100 frequently encountered species were Festuca rubra Observations2000 1069 (43.1%), Phragmites australis (30.2%) and Calama-

ECOGRAPHY 26:6 (2003) 709 The results suggest that the LWfG concentrated on Hailuoto and nearby areas (Markkola 1992, Markkola feeding on Festuca rubra and Phragmites. Where these et al. 1993) that the spring diet of LWfG consists two species were abundant locally, the LWfG have not almost entirely of Monocotyledons. Also in the impor- consumed many other species. In multi-species drop- tant staging area at Porsangerfjord, northern Norway, pings the proportion of the main species was the a grass, Puccinellia phryganodes, is normally the main highest, 81.2%, in Phragmites dominated droppings. diet. In spring 1996 when the grass meadows were The LWfG rarely concentrated on species other than covered by ice until very late in the spring LWfG used these two and almost never fed exclusively on species a dicotyledonous species Hippuris tetraphylla that was other than Festuca or Phragmites. practically the only forage available (Aarvak et al. LWfG preferred in descending order Phragmites aus- 1996). Both of these species also grow sparsely at tralis (o=0.73), Triglochin palustris (o=0.7) and Fes- To¨mppa¨ meadow but were not found in the diet. tuca rubra (o=0.52). Calamagrostis stricta (o= Cultivated species were not observed in the diet of −0.47), Juncus gerardii (o=−0.59), Agrostis sp. (o= LWfG on Hailuoto. Most of the few cases when we −0.83), Carex sp. (o=−0.89), Eleocharis sp. (o= have seen LWfG feeding in fields and eating mainly −0.99) and Dicotyledons (o=−0.99) were not se- Phleum pratense L. grass were under retarded spring lected. The LWfG did not exploit monocotyledonous conditions when the meadows were covered by ice species Triglochin maritima (L.), Potamogeton spp., (Markkola 1992, 2001). Eriophorum angustifolium (Honckeny), or a long list of The Hungarian steppe, ‘‘puszta’’, has been the west- Dicotyledons, all of which had an o-value of −1. ernmost highly important autumn and spring stop-over All the p-values except Triglochin palustris (p= for the LWfG during the 20th century, in 1950s still 0.125) were statistically significant (Fig. 2). The great hosting up to 50 000 individuals per season (Sterbetz variance of the electivity index in this species was 1978). Sterbetz (1978, 1990) found Festuca pseudo6ina caused by the fact that it was rare both in the field and Hackel ex Wiesb. grass to be the outstanding fall feed in the diet. Probably it was preferred, but a larger of the LWfG. Most F. pseudo6ina steppes with a high sample is required to confirm this. calcium content have been ploughed, but they still exist in nature reserves like Hotoba´gy and Kardoskut (Ster- betz 1990). In wintering areas of Azerbaijan and Armenia, Discussion LWfG are to some extent grazing in fields on wheat, Diet of the lesser white-fronted goose barley and maize (Zea mays L.) but they are also said to prefer feeding in steppe grasslands where sheep Table 3 summarises the results of diet studies of the grazing maintains low vegetation growth (Lorentsen et LWfG. Our study confirms earlier observations from al. 1999). At East Dongting Lake, China (29°10%N,

Fig. 2. The distributions of Chesson’s electivity indices and the empirical p-values of 1000 bootstrap re-samples: grey rectangles=50% of values, black line inside the rectangle=median, segment of line=holding 80% of observations, circles=extreme 20% of observations.

710 ECOGRAPHY 26:6 (2003) Table 3. Known dietary species of the lesser white-fronted goose. Preferred species have a rank number (1) after their Latin name. In most short notes about the diet of the LWfG there is nothing mentioned about the preference and the species are in a random order. *=cited by Cramp and Simmons (1977).

Source dietary plants area season

this study (the order is according to grasses: Phragmites australis (1),Isle of Hailuoto, Bothnian Bay, spring the electivity index) Festuca rubra (3), Calamagrostis Finland stricta (4), Agrostis sp. (6) other Monocot.: Triglochin palustris (2), Juncus gerardii (5), Carex sp. (7), Eleocharis sp. (8) Dicot.: Dicotyledonae sp. (9) Markkola 1992grasses: Agrostis stolonifera, Isle of Hailuoto, Bothnian Bay, Festuca rubra, Calamagrostis stricta Finland other Monocot.: Juncus gerardii Markkola 1992, Markkola et al. grasses: Phleum pratense (coastal Bay of Liminganlahti, Bothnian 1993 ﬁelds) Bay, Finland other Monocot.: Carex halophila, Carex mackenziei, C. paleacea Aarvak et al. 1996grasses: Puccinellia phryganodes (1) Porsangerfjord (Valdak), Norway Dioct.: Hippuris tetraphylla Morozov 1988 grasses: Arctophila ful6a N part of the Ural Mountains, summer Bolshezemelskaja Tundra Lorentsen and Spjøtvoll 1990other Monoct.: Carex bigelowii, Nordland, Norway (Scandinavian Carex nigra ssp. nigra, C. nigra Mountains) ssp. juncella, Eriophorum scheuzeri, E. angustifolium, Trichophorum cespitosum Dicot.: Polygonum 6i6iparum, Leontodon autumnalis, Taraxacum sp. horsetails: Equisetum palustre Nettlebladt 1992other Monocot.: Carex aquatilis, Nordland, Norway Eriophorum angustifolium, Juncus arcticus, Luzula multiﬂora Dicot.: Petasites frigidus, Polygonum 6i6iparum, Salix lanata horsetails: Equisetum palustre Markkola 1992, Markkola et al. other Monocot.: Carex rostrata, C. Lapland, Finland 1998a chordorrhiza Dicot.: Empetrum nigrum berries *Scott ym. Dicot.: Salix herbacea Lapland/Finnmark *Zharkova and Borzhonovother Monocot.: Eriophorum Taimyr, Russia angustifolium, E. scheuzeri Aarvak et al. 1996 grasses: Festuca rubra, Puccinellia Porsangerfjord (Valdak), Norway autumn phryganodes, Agrostis stolonifera, Elymus arenarius other Monocot.: Eleocharis uniglumis, Juncus gerardii Tolvanen 1998 grasses: Puccinellia phryganodes Kanin Peninsula, Russia other Monocot.: Carex subspathacea Dicot.: Hippuris tetraphylla Tolvanen et al. 1998 Dicot.: Empetrum nigrum berries Varangerfjord, Norway Markkola et al. 1998b Dicot.: Empetrum nigrum berries Isle of Hailuoto, Finland Sterbetz 1978 (1990 in text) grasses: Festuca pseudo6ina (1), Carpathian Basin, Hungary Gramineae sp., Triticum 6ulgare, Poa sp. Dicot.: Chenopodium sp., Achillea sp., Sinapis sp., Eryngium sp. Markkola et al. 2000Dicot.: Rorippa sp. China winter

ECOGRAPHY 26:6 (2003) 711 113°50%E), where \50% of the known world popula- Therefore it was difficult to conclude the importance of tion of the LWfG are currently wintering, LWfG the chemical composition in diet selection. However, mostly used grasslands (88%), where the dominant some patterns were found: the content of soluble carbo- plants were sedges and grasses (Markkola et al. 2000). hydrates, but not that of protein, ranked the species in The gizzard of a poisoned 2nd calendar-year male the same order as their favour by LWfG. The rank in LWfG, however, contained only Rorippa sp., a di- fibre content, as expected was near the opposite to the cotyledon (Markkola et al. 2000). rank in LWfG preference. In summer, the fundamental difference compared with migration and wintering is the molting and brood rearing period, when a LWfG family does not fly for Management of lesser white-fronted goose staging 6–7 weeks. One could expect that summer diet is not as meadows limited as in other parts of the year. The 18 species listed for summer (Fennoscandia, Table 3) compared The traditional use of coastal meadows of the Bothnian with the 9 taxa of this study or all 14 species listed for Bay was mowing in mid-summer and grazing of cattle spring (Finland–Norway, Table 3) support this idea. in late summer, a practice, which ceased gradually in The summer diet also differs from the normal grass the 1950s. Since 1986 the To¨mppa¨ meadow has been dominated pattern. managed again by mowing, thanks to the local hunting Despite the huge geographical scale concerned, there association which has tried to improve conditions for is a lot in common in the diet of the LWfG and the waterfowl and hunting and conservationists who have other geese. However, in staging areas, LWfG prefer tried to improve conditions for threatened bird and natural habitats more than other geese. In Hungary, plant species. Mowing has improved the conditions for LWfG prefer natural steppe whilst white-fronts and staging LWfG, breeding birds such as southern dunlins (Calidris alpina schinzii Brehm) and for rare plant spe- bean geese mostly graze in fields (Sterbetz 1978, 1990). cies like the arctic salt-grass (Puccinellia phryganodes) Along Bothnian Bay coasts in Finland, LWfG mostly and the Siberian primrose (Primula nutans Georgi) use coastal meadows, where the taiga bean geese use (Markkola and Merila¨ 1996). Encroachment by reed fields (Markkola 1992, 2001, Markkola et al. 1998a). beds and willow bushes that have invaded the open This dependence on specific places supporting special meadows has been reduced. habitats may make the LWfG vulnerable to continued The draft management plan for the area (Markkola habitat loss and illegal hunting in the few remaining and Merila¨ 1996) suggested mowing and grazing ac- concentrations. cording to the traditional management scheme. It is, however, more probable that the new management method will be continuous grazing in June–August, as Factors affecting diet selection natural pastures are effectively promoted in the EU through agri-environment scheme support. Grazing can Based on the results of this study and existing knowl- even, more effective than mowing, improve conditions edge, the LWfG is not strictly limited to a few particu- for plants, which are preferred by the LWfG. lar plant species. Probably the most important factor The common reed Phragmites australis can have an leading to a limited list of dietary species is its need for adverse effect when it encroaches on open coastal a special feeding habitat, which according to our results meadows but at the same time it was the most preferred is an extensive coastal meadow, at least tens of hectares dietary species of the LWfG. LWfG never fed in dense \ wide and 300 m broad. The LWfG is, at least in and tall reed stands, but searched out short and scat- Bothnian Bay staging areas, more shy than other geese tered reed shoots. In an ideal situation Phragmites will (Markkola et al. 1998b). Disturbance from people and survive sparsely among lower vegetation. To ensure the vehicles is less frequent on the remote coastal meadows survival of sparse Phragmites stands, the meadow could than in agricultural areas. Also Sterbetz (1990) stressed be divided into management segments, of which each the lack of disturbance in large puszta areas as a reason could be cut every second year or in two years out of for the LWfG to use this habitat in addition to the three. morphological feature of the LWfG, which has a short If grazing begins, maintaining of Phragmites requires bill adapted to intake of short-growth plants. moderate grazing pressure. The negative effects of graz- Within suitable habitats, the quality of different ing on reed will probably be balanced by expansion of plants is probably the main factor leading to diet Triglochin palustris and Puccinellia phryganodes, which selection by the LWfG. The quality of food varies in are capable of colonising the bare substrate created by different components such as the protein content, solu- cattle (Kauppi 1967). Where pasture can be divided ble carbohydrates, energy and digestibility. We did not into two–three segments, one–two could be grazed and carry out chemical analyses and the data in the litera- one–two left untouched annually to favour also breed- ture are heterogeneous (Thomas and Prevett 1980, ing birds, as trampling of nests is avoided in untouched Sedinger and Raveling 1984, Budeau et al. 1991). segments (de Jong 1977).

712 ECOGRAPHY 26:6 (2003) One important point in management of the LWfG Iwabuchi, S. et al. 1997. The short report on survey of lesser meadows of Hailuoto is the need for a hunting ban in white-fronted geese at Donting lakes in China. – Bull. Sci. Mus. 7: 103–105. this area, which is a candidate site for inclusion in the Kauppi, M. 1967. U8ber den Einfluss det Beweidung auf die Natura 2000 network of the EU. At the moment, Vegetation der Uferwiesen an der Bucht Liminganlahti im wildfowl shooting occurs during the main autumn mi- Nordteil des Bottnischen Meerbusens. – Aquilo Ser. Bot. gration period through the area, which is also a poten- 6: 347–368. Krebs, C. J. 1989. Ecological methodology. – Harper Collins. tial autumn staging place for LWfG. Lorentsen, S.-H. and Spjøtvoll, Ø. 1990. Notes on the food choice of breeding lesser white-fronted goose Anser ery- Acknowledgements – This study is a part of the study and thropus. – Fauna Norvegica Ser. C, Cinclus 13: 87–88. conservation work carried out by the Lesser White-fronted Lorentsen, S.-H., Øien, I. J. and Aarvak, T. 1998. Migration Goose working group of WWF Finland and Finnish conserva- of Fennoscandian lesser white-fronted geese Anser erythro- tion authorities, the Nordic Lesser White-fronted Goose Pro- pus mapped by satellite telemetry. – Biol. Conserv. 84: ject (including NOF/BirdLife Norway) and the Lesser 47–52. White-fronted Goose Task Force of Wetlands International. Lorentsen, S.-H. et al. 1999. Lesser white-fronted goose Anser The Finnish Academy, Maj and Tor Nessling Foundation and erythropus. – In: Madsen, J., Fox, T. and Cracknell, J. NorNet/Focus area Environment of the Univ. of Oulu have (eds), Goose populations of the Western Palearctic. Wet- supported this study financially. We thank Tony Fox, Seppo lands International, Cambridge, pp. 144–161. Haapala, Jari Heikkinen, Satu Huttunen, Anja Hohtola, Madsen, J. 1996. 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