JoURNAL oF TRoprcAL BroLoGy AND CoNSERvArroN, 2 (1) : 1-8, 2006

Research article

A survey and study on food habits of migratory waterbirds along Lake, Oriental Province, Philtppines

Grace B. \TILLAMOR*

ASEAN Regional Cente for Biodiversity Conservation (ARCBC) Its Baios, Inguna 403 I . Current address: World Agroforestl Centre (ICRAF), Philippines

ABSTMCT. This survey showed that Naujan INTRODUCTTON Lake is an important stop-over for migratory birds. A total of 9,225 counts of waterbirds For many centuries people have observed the belonging to 14 species and six families were regular seasonal arrivals and departures of recorded and identified along . birds. Asia and the western Pacific are Yast The counts were obtained using a combination route-maps of waterbird migration paths, of survey techniques. namell: imaginary covering tens of thousands of kilometers, As transect counts, actual headcounts, autumn approaches, the many millions of ethnobiological interviews, and general waterbirds in the northem area depart on long obse ation. For food-habit analysis, three journeys southwards. They pass through waterbirds, Aythya fullgula (Tufted duck), many Asian countries between August and Egretta alba (Gteat egret), arld Stema hirundo November to spend the cold northem \ inter (Common tern) were selected to undergo in milder climates on the tropical and warm stomach analysis and actual observation. In temperate wetlands of eastem and southern this way, their food preferences were Asia (Sonabe, 1993). determined. Through local interview and actual observation, the movement of the tufted The Philippines with about 7,100 islands and ducks around the lake as well as their time of 186,000 kn'?of land scattered ovff 800,000 kr'] arrival and departure were described. The lake of the westem Pacific Ocean is the southem still possesses diverse amphibious and terminal for most of the migrants moving south aquatic plants which are beliered to sustain east along the eastAsian flyway. It is perhaps the seasonal visitation ofthese bird migrants. the multiplicity of small islands, reefs and However, the vigorous fishing activities in the shoals and the immense length of the coastline area pose a setious threat for them. and wetlands that make it so spectacular. Of the 556 species that are on the Philippine list, 171, (30.8Vo) are migrants (Dickinson er a/., 1991). There are three major known sites in Key words: Migratory waterbirds, Naujan Lake, Food the Philippines harbouring bird migrants, habits namely: Na-awan, Misamis Oriental, *:gracev4o30@ lycos.com; agila [email protected] FOOD HABIIS OF IIIGR{IORY WAIERB]RDS ALONG NAUJAN LAKE, OrurNrer- MrNoono PRovtNCE. PHrLrpprNEs

Figure 1. Map ofNaujan Lake, , Philippines (Scale: I :100,000)

Minadano; at Dalton pass, Nueva Viscaya, this leason. there must be wetlands at either Luzon: and lu ahig. . Anorhcr pror in,. e end of the flight, which can provide in the Philippines that possesses porertial sustenance for waterbirds on the move. But habitats for these migratory waterbirds the wetlands i1r Naujan Lake, although it is is Mindoro. saiC to be a protected area, is endangered, due t{r tlle conrcrsion of forest lands into Why birds migrate is stil1 one of the most agricu.Ltural lands and hampered by modern challenging questions. Very little has been technolog), (such as application of fefiilizers published about migration in the Philippines, and herbicides that flow into the lake). The excepl u hat has been leamed through ring ing. birds inhabiting the area are not fully recorded. nhich uas dercribed by McClure rn an Thus. bcfore conversion of the study area unpublished repott, Migrdtion ancl Sul'vival proceeds, there is an immediate need fcr a of the Birtls ofAsia. Because we do not fully sur\ ey. Arother problern in the alea concerns understand the evolutionary oligins of netti[g (done by fishermen as source of migation and have not been able to document Iivelihood) and unregulated hunting during the behaviour of long-distance migrants emoute, visiring season. Therefore, before tltese lhere is a big need to \tud) these bird'. lou'land habitats and waterbirds completely disappeai, records must be securcd.Moreover, Migration flights of any distance require the the data and information fron this study will use of much energy in a very short time. For serve as baseline information for the Grace B. VILLAMOR preparation of a master plan and/or Survey techniques management plan for the protection of the lake as well as for understanding the behavior and A combination of survey techniques was pattem ofmigration in the lake. employed in the study site to assess the presence of the migratory birds and their The objectives ofthis study are (l) to identify frequency. These were imagilary transect the migratory waterbirds in the study site: (2) counts, actual headcount, general observation to record the food habits of the selected using field binoculars (8 x 211-'l x 50) and migratory waterbirds; (3) to determine the time ethnobiological interviews with the residents, oftheir arrival and departure in the study site; fishermen and other stakeholders along the (4) to assess the effect of conversion of study site. Actual headcounts and forested areas; (5) to know the extent of observation were done at daylight hours hunting; and (6) to make recommendations for between 6:00 am and 9:00 am, counting all the thet management. adults and juveniles. Identification was done based on the monographs of DuPont (1971) MATERIAISANDMEIIIODS and Sonabe (1993) while taxonomy and nomenclaturs were based on Dickinson Study Site et al. (1991) .

Naujan Lake is the largest freshwater lake in The food habits of selected waterbirds were Odental Mindoro Province with an area of determined through stomach analysis and about 8,000 ha and is the 5'h largest lake in the direct obseNation while selection of birds was Philippines. It is located in the northeastem based on population size and frequency. section of the province and is bordered by Movement and time of arival and departure the municipalities of Naujan, Pola, Mctoria and was observed during the study period with Socorro (Fig. 1). The lake is categorized by the guidance of local fishermen in the area. the Irtegrated Protected Areas System (IPAS) Vegetation was determined by ground survey, as wildlife sanctuary and tesource reserve and community map sketching, and map overlays is designated as "Wetland of Intemational tiom the Department of Environment and Importance" (see http://www.worldlakes.org). Natural Resources (DENR) Municipal Office. It is a pdmary lake habitat where famous freshwater fish such as "bangles", "simbad", RESI]LTAND DISCUSSION and "langaray" can be found that serve as a possible food source of visiting waterbirds. Survey The types of wetland ecosystem found in Naujan Lake are swamp forest, marshland, A total of9,225 counts of waterbirds belonging and estuaries. to 14 species and six lamilies was recorded and idenrified in the study site (Tab1e i). Five Time of the Study species were winter visitors; one as passage visitor and the rest were non-endemic resident The study was conducted between October birds which are present all year round. Based 2b. lgg? and February 28. I 9q8. Observatjon on interviews, two species (Anas luzonica was done every Saturday and Sunday from6:00 IPhilippine Mallard] and Thre skioruis a.m. to 10:00a.m. and4:00p.m. to6:00p.m. melanocephalus [Black-headed Ibis]) were present in the area, but were not encountered during the survey period. FOOD HABITS OF MIGRATORY WATERBIRDS ALONG NAUJAN LAKE, ORTENTAL MrNDoRo PRovINcE. PHrLrpprNEs

Irgend: lT? r a,-I 9 * - Marshland lv ' I Fgia - Forcsted Area M - Orchards / Coconut Plantation

- Flock Of Ducks

Figure 2. Movemenl of the Aythya fuh gala by flocks in Nauj an Lake Grace B. MLLAMOR

Table 1. List of birds observed and recorded from Naujan Lake, Oriental Mindoro Province, during the period of October 1997 - February i998

Family/Scientific Common Name Counts Mode Status Name

Alcenidae Halcyon chlorosts White collared kingfi sher 11 Sightings resident

Anaaidae Aythyafuligula Tufted duck 8944 Sightings/ wintervisitor caught Dendroqtgne arcuata Wandering whisding duck l5 Sightings resident

Ardeidae Ardea sumatrana Giant-billed heron 11 Sightings resident A. purpurea Purple heron 5 Sightings rcsident Egrelta alba Great egret 38 Sightings winter visitor Ixobrynchus sinensis Yellow bittem t2 Sightings resident ,1 I. cinnamomeus cinnamon bittem Sightings rcsident

Pycnonotidae Pycnonotus goiavier Yellow-vented bulbul JA Sightings resident

Rallidae Gallinula chloropus Common moorhen 24 Sightings resident Gallicrex cinerea Watercock 3 Sightings resident

Rostratulidae Ras t r atula b e n I ale n s i s Great Painted-Snipe 2 Sightings resident

Scolopacidae Gallinago megala Swinhoe's snipe 6 Sightings wintervisitor G gallinago Common snipe 9 Sightirys wintervisitor

Sternidae Chlidonias hybidus Whiskered tem 32 Sightings wintervisitor Stema hirundo Common tem g8 Sightings wint€rvisitor

Species sighted by ffshermen

Anatidae Anas luzonica Philippine mallard endemic

Threskiornithidae Thre s kio rni s me lanocephalus Black-headed Ibis winter visitor FOOD HABITS OF MIGR,{TORY WATERBTRDS ALONC NAUJAN LAKE, OnreNrer Mnoor'o Pnovmce, PHrnenres

Table 2. Food-habits of sample specimen from Naujan Lake, Or. Mindoro

Species Foods FoodGuilds

Aythya fuligula Venas sp. Camivore Stema hinnda Ctenogobius criniger Piscivore Egrettq albq C. cringer Piscivore

Thble 3. List of important amphibious and aquatic plants still found in the Naujan Lake (Davis, 1991).

Position/mode of growth Species

Ladw:ad Amphibious Ludwigia octovalis

Emergent creeping Echinochloa stagnina Ludwigia adscendens

Emergent S accharutn spofi,taneum Scirpus grossus Nelumbo nucifera

Free floating Eichhomia crassipes Azolla pinnata

Floating leaved Nynphaeae nuochali

Submerged, rooted Najas indica Uallisneria gigantea Hydrilla verticillata Pota Logeton sp.

Lakeward Submerged, unrooted C e rat op lry llum de m e r s urn t l, Grace B. VILLAMOR '7 The most abundant bird species observed in Among the three, the food habit of Aythya the lake was A)rry.r/uligrla (Tufted duck). A fuligula rs different, as indicated by gizzard I total of 8,944 individuals oftufted duck were content, a certain species of bivalve is the recorded on the waters of Naujan Lake. As prefered food. I I shown in Fig. 2, thre e flocks of Aythya fuligula were often obseryed. The flocks were located Habitat Condition near Malabo and Barangay Balansig, while the other was found at the no heastem The lake displays a rich diversity in tems of portion of the lake. They were observed amphibious and aquatic plants (Davis, circling in groups at a certain time of the day unpublished report) , which were observed around the said locations. These birds are existing during the survey (Table 3). The good divers and stay throughout the day on presencc of rhese relalivel) direrse aquatic the water. plants in the lake is believed to be essential for maintaining the water quality and fish Other interesting waterbirds observed were diversity that support waterbirds in the area. the terns. Two species were identified, Steraa hirundo (Common tern) and Chlidonis Flocks ofwaterbirds and openland birds were iyDridas (Whiskered tern). They were the often observed in the northem portion of the most active waterbirds in the area, often seen Iake. where marshlands and associated at the mudflats and grassbeds. vegetation exist. Only low numbers of birds were obseryed in the southem portion of the Aythya fuligula, Sterna hirundo, Chlidonis lake. where there are limited areas of marsh hybridus, Egretta alba (Great egret), due to human habilation and lind con \ ersion. Gallinago negala (Swinhoe's snipe) and G Most of the forest land had been converted gallinago (CommorL snipe) are winter visitors to coconut plantation and orchards, which can from either northem or southem hemisphere. be seen in the eastern and southern ponion They arrived at the lake and stayed lbr more ofthe lake. Threatis alarming on the landwad than five months - from the first week of side. According to the residents, the western October to the first week of March. portion ofthe lake was once thickly forested, until logging concessionaires cut the kees and Food Habits Analysis left only a small pofiion of the forest. The isolated forest is dominated by species of Three species were selected tbr food habit Tenninalia, Nauclea, ar,d Flcas. The whole a:ralysist Aytlxya luligula, Stema hirundo, area is covered by numerous claims (Rights a\d Egretta a1Da. Selection was determined or ownership of the land around the lake) by their population size and frequency. Table despite the declaration as a National Park. 2 shows their specific food preference. Some orchard plantations are now being planted with annual crops on steep slopes, A whole body of fish (.Glossogobius sp.) was which consequently may cause siltation and recovered from the gizzatd of Sternahirundo. eufophication. Electrofishing is still a practice This could be the reason why most of the terns which affects the food source of waterbirds. were found in shallow waters especially near Unfortunately, the assessment on the eJlect the tish pen where they dive for fish. The same of forest conversion was not achieved due to species of fish was found in the gizzard of limited data and resources. Egretta alba. These suggest that the two species are piscivores. FOOD HABITS OF MIGRATORY WATERBIRDS ALONG NAUJAN LAKE, ORrei'{rel- MINoono PRoVINCE. PHILIPPTNES

Bird Hunting and liapping SUI\,IMARYAND CONCLUSION

Based on local interviews, from previous The survey shows that Naujan Lake is an yea$, amateurs andprofessional hunters ftom important stop-over for migratory birds. Its neighboring municipalities and provinces dense marshland and weed beds attracted made Naujan Lake a favorite spot forhunting thousands of waterbirds, especially Aythya ducks, and almost 20,000 ducks were shot in fuligula. The lake still has good water quality just one week of hunting. On the other hand, due to the diverse amphibious and aquatic during the study period, waterbirds, especially plants where fishes and other waterresources the tufted ducks, were highly disturbed due are abundant for the sustenance of these to vigorous fishing activities. The use of gill migratory bfuds. This should notbe neglected, nets ffapped these diving ducks and killed but rather must be maintained to support the them by drowning. Approximately 20 diving biodiversity living therein. This study ducks every day were killed by nets and brought suggests to conduct a more rigorous study to dle market to sell for Php 20.00/duck. on the whole ecological profile of the lake including its biophysical and socioeconomic Recommendation profiles, to describe the conservation measures better. The marsh and the westem portions are of great value for migratory birds. Thus, ACKNO\ryLMGMM.{TS protection should be focused on these areas. Following are some recommendations for the The author would like to thank PARRFI of the protection of migratory birds in the area: Philippine Council for Agriculture, Forestry Annual monitoring and inventory of and Natural Resources Research and waterbirds. parricularly during r isitation Development (PCARRD), Los Baflos, Laguna, period. Elechofishing is a destructive fishing Philippines, for providing financial assistance practice in the area and should be strictly in the conduct of this study, and to Mr. Jerome prohibited. while during visitation period of Alano and Ms. Rexie Jane Parreflo for the migratory bird (Oct - Mar), the use ofgillnets satellite map and editing. for fishing should be avoided, particularly in the northem and westem portion of the lake. RmmE,ICES Since most of the residents depend on fishing and farming as source of income, livelihood Dickinson, E.C., R.S. Kennedy & K.C, Parks. activities that will not depend on nearby (1991), The birds t'f the Philippines. Bi.tish resources (e.g. handicraft making) should be Omithologists' Union, UK. introduced. Swamp forest in the marshland DuPont, J.E. (1971), Philippine birds. Delaweje should be rehabilitated with original flora. Museum of National History. Greenville, Delaware. USA. Naujan Lake is a National Park, its regulations must be stricdy implemented including regular Goualez, J.C,T. (2003). Ar avifaunal survey of monitoring and inspection.It is also suggested , Oriental Mindoro Province, that a more rigorous study on the whole Philippines. Aria Lrre Science,2: 163-1'76. ecological profile of the lake must be undertaken to better describe the conservation Sonabe, K., & S Usui. (1993). A field. guid.e to the waterbirds ofAsia.l'lild Bird Society of Japan measures for the whole lake including the use and hinceton University Prcss, Einceton, USA. of GIS tools (as one possible way) to address the effect of forest conversion on the lake.