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Food Supply of Purple Disturbed by Local Fishing in Bung Khong Long Lake,

Kanongdate K* Research Article Faculty of Environment and Resource Studies, Mahidol University, Thailand Volume 5 Issue 3 Received Date: August 16, 2021 September 02, 2021 *Corresponding author: Kamalaporn Kanongdate, Faculty of Environment and Resource Published Date: Studies, Mahidol University, 999 Faculty of Environment and Resource Studies, Mahidol DOI: 10.23880/jenr-16000251 University, Phuttamonthon 4 Road, Salaya Sub-Distric, Phuttamonthon Distric, Nakon Pathom, Thailand, 73170 Tel: +66 89 687 3116; Email: [email protected]

Abstract

Abundant wetlands are generally considered providing the fundamental niche to multi- diet feeders like Purple Heron ( purpurea of A. purpurea L) whereas the realized niche may be over-looked. This study hypothesized that the fluctuation of observed number decreasing to 6 individuals between 2009/ 10 and 2010/ 11 even though the status is least concern for the country. Due to its at Bung Khong Long Lake (Ramsar Site) has influenced by local fishing since the maximum number was observed

feeding behavior on not specific preys, all possible food sources was sampled following the feeding route of Purple Heron and time of Purple Heron. Field investigation was conducted in early (EP), middle (MP), and late (LP) period of migratory season then was compared with -caught by local fishing per day, as well as observed fishing activities to cross check with feeding

2009/ 10 and 2010/ 11 and cross check with the official recorded number of Purple Heron obtained from the Department of appeared to be the priority preference for Purple Heron’s feeding that was sampled higher in 2010/11 compared to 2009/10 National Parks, Wildlife and Plant Conservation, Bangkok. Size and type of preys (seven fish ; medium size ~5- 15 cm)

migratory season (p = 0.003) and also seemed to be the common fish caught by local anglers. In addition, fish biomass has more or less influenced on the frequency of feeding rather than the number of fish and it showed significant highest in EP (p = 0.002) and less in LP as well as higher observed-number of Purple Heron in EP than LP. Based on daily required 200g/ -2 day-1; EP, 256.75 g m-2 day-1; MP, and 343.37 g m-2 day-1 ; LP, day/individual, all food sources (mainly fish) sampling in the field insufficiently played a role as the hypothesized-realized -1, which is higher niche for the maximum number of A. purpurea (606.08 g m than the hypothesized-realized niche that might push the to move out and shift to the better foraging places. respectively). Whereas, fish caught on the seven species by local anglers resulted around 66,707 g m 2 day

Keywords: Fishery; Foraging; Purple Heron; Ramsar; Wetland

Introduction in Thailand was noted as vulnerable Sanguansombat [4] and it has been observed in small numbers at Bung Khong Long Purple Heron (Ardea purpurea L. Lake (Ramsar Site). A. purpurea is reported to be commonly as endangered to vulnerable and currently as least concern in found as non-breeding visitor in the suitable environment the IUCN red list [1-3]. However, Ardea) was purpurea globally manilensis classified and habitat across Thailand Robson [5] especially mostly

Food Supply of Purple Heron Disturbed by Local Fishing in Bung Khong Long Lake, Thailand J Ecol & Nat Resour 2 Journal of Ecology and Natural Resources found during the migratory season between Octobers to Aprils. During the migratory season in Thailand, the weather Thailand [10]. Bung Khong Long also serves as an important is comparatively warmer than original places in that been also classified as the national vulnerable species of is the wintertime where they moved from McClure [6]. The Brachygobius sp. , Clupeichthys aesarnensis, Monotrete leiurus non-breeding visitors have moved to join the resident in (previoushabitat of named the endemic Tetraodon fish leiurus),species suchNeodontobutis as Boraras auramus, micros, some areas in the north, northeastern, central, and south of and Rasbora spilocerca ONEP [11] Wetlands International Thailand [5]. Most research on A. purpurea were carried out in breeding grounds, thus information on their ecology and feeding behaviors at the migratory areas is still lacking and have[10] andbeen they observed play significant at this place role asboth economic residences fish thatand unclear. An attempt to study the food sources of Purple Heron passing-provide income visitors. to Some local offishers. those Severalbirds have kind been of avian reported species as at the breeding area in the south of Thailand was conducted the nationally endangered species including Ardea cinerea, by Kanjanasaka [7]. Their study serves as basic knowledge A. purpurea, and Milvus migrans. Some vulnerable species of a type of preys preferably fed by the Purple Heron that observed at the lake such as Aythya nyroca and Vanellus supported sampling design in this study. A. purpurea duvaucelii [10]. A. nyroca has been also globally recorded as manilensis at Bung Khong Long Ramsar Site has not yet a near threatened species and three species are nationally near threatened species namely Haliastur indus, Nettapus previously it used to be the visitor and had become resident coromandelianus, and Vanellus cinercus [10]. been clearly defined whether it is the resident or visitor or this Ramsar Site was ever high up to 20 individuals DNP [8] Food of Purple Heron butuntil there present. were However, only 6 individuals the maximum observed number during observed migratory at season of 2009/10 and 2010/11. The decrease in the A. purpurea has been observed and reported feeding

sources [7,13,14,16-23]. In India, A. purpurea has been maximum number of Purple at Bung Khong Long mainly on fish [12-15] but also have other alternative food Lake was hypothesized that has been influenced from local fishing that likely making the birds have difficulty to access reported fed on mainly fish about 57%, reptilesA. purpurea 20.57% are which able to foodReviewed sources or Literatures insufficient food supply or both cases. are mostly , shrimps and crabsAnguilla 14.34%, anguilla, and Lepomis gibbosus,7.65% [24]. Rutilus Barbraud rutilus [16] to reportedinsects such that as larvae of Hydrous Study Site spto . shiftThe study the preys of Kushlan from fishand likeHancock (2005) also indicated A. purpurea included , Bung Khong Long Lake, the largest freshwater lake Cyprinus, Tinta, Abramis, Scardinius, Perca, Anguilla, Acerina, 2), is located in the Northeastern Lota,the group and ofMugil fish. However, mostly fed other by food types are included Thailand (17°18´-17°58´ N and 103°59´-104° E; 160-170 m) and(approximately was dominated 22. 4as km the second Ramsar Site in Thailand, reptiles and small birds Barbraud [15,16]. Kanjanasaka [7] whilst it has been also holding the status wildlife non-hunting alsofrogs, reported aquatic thatinsects other [16,13-15], food sources shellfish, found small at the , breeding area in 1982 proclaimed by the Royal Forest Department [9]. areas in Thailand are (e.g. Metapenaeus sp.) and reptiles (mainly snakes of family Acrochordia e. g. drainage of streams and rivers especially Songkram River Acrochordus javanicus and Homalopsinae e.g. Enhydris The lake has a narrow oxbow shape and has backed up the enhydris Procambarus clakii) was reported as a major prey for adult A. purpurea in Portugal Correia [18] inhabitants.before flooding The intolake also Mekong serves River. as natural Adjacent food areas and income around ). Crayfish ( the lake are paddy fields, Para rubber crops, and local wild resource collecting. bywhereas A. purpurea sunfish and larvae were reported as a major sources for local people living in this area through fishing or Labeoprey in altivelisItaly [25]. (Rednos Hockey Labeo),[21] defined Labeo mainly cylindricus fish species (Redeye fed Scattered emergent hydrophytes covered water surface Labeo), Oreochromis in macrochir comprise (Greenhead with Clarias sp. ),(catfish), Tilapia in wide area in the lake that becomes an important factor rendalli (Redbreast Tilapia), and Brycinus imberi (Spot-tail). attracting many kinds of to survive. They play a role According to Kushlan and Hancock [22], A. purpurea little birds, and others, as well as being a pathway for some of being habitat and food sources of some fish, invertebrates, cm. As well as the study of Moser [23], he reported that as Purple Heron. The lake was eligible for being a Ramsar Cyprinuspredate on of size large 2-5 fish cm, with mullet size or varied Mugil betweenof size 4-5 2 cm, and and 35 birds to rest and camouflage during foraging time Betta such eel (Aguilla) of size 25-35 cm were mainly fed by A. purpurea smaragdina and B. splendens, as well as other crucial fish, Sitesuch as due Kryptopterus to the threatened bicirrhis and fish Clarias species, batrachus namely that have were fed by this but not mentioned the species or group in France. Moltoni [25] also reported the fish of size 2-10 cm

Kanongdate K. Food Supply of Purple Heron Disturbed by Local Fishing in Bung Khong Long Copyright© Kanongdate K. Lake, Thailand. J Ecol & Nat Resour 2021, 5(3): 000250. 3 Journal of Ecology and Natural Resources

a proportion of the total area of lake. Abbreviations present in the Figure 1 represent the name of investigated stations feedingof fish. However,their chicks it is since likely most possible researches that Purple were Heron conducted feed (DMT = Don Mor Tong, DST = Don Seo Tai, BCS = Ban Chareon aton thethe breedingsmall size grounds of fish [26].because In Thailand,they need Kanjanasaka such a size [7]for Suk, HPT = Huai Pong Tao, DSW = Don Sa Wan, NEY = Noan A. purpurea at Eee Yord). the nest included Cyprinidae (Rasbora aurotaenia or Rasbora retrodorsalis),reported the fish Channidae from 8 families ( fed striataby young or Ophicephalus striatus), Anabantidae (Anabas testudineus), Notopteridae (Notopterus notopterus), Clariidae (Clarias sp.), Belonidae (Xenentodon cancila), Aplocheilidae (Aplocheilus panchax), and Mugil sp.

Food uptake of A. purpurea was estimated 200 g per day Bauer [27] that make the bird to meet metabolic rate of between 4.36 and 5.21 kcal per day [28]. Campos and Lekuona

[17] suggested that in breeding area, fish size between 1 andA. 12.5purpurea cm have the most profitability than size of 12. 5 – 25 cm wherecm [26]. frequently However, observed Campos andin Bung Lekuona Khong [29] Long suggested Lake that that A. purpurea mostly predate on fish size between 5 and 12.75 than the size of 1-12.5 cm in the breeding areas. In case of captured fish of size 12.5-25 cm more frequent capturingMethodologies larger fish, high number of fish is not the matter.

Field Observation

Field investigation was conducted within the area Figure 1: Gridding measurement overlaid on Bung Khong of Bung Khong Long Lake in 2 migratory seasons of year Long Lake created by Kanongdate [26]. 2009/10 and 2010/11 (October to April). An entire area of the lake was estimated 22.14 km2 or 22,140 m2. To make the feeding area comparable with the lake area, gridding was All grids were 23.9 units in total covering the entire area applied for creating a section covering on the body of lake as of lake. Only 11.5 grids cover the potential feeding areas of shown in Figure 1. One grid was counted as 1 unit and the area A. purpurea covered by a half of grid was counted as 0.5 unit, and other km2 or 11,070 m2). Area size of each station presents in Table proportions depended on the areas presented in the grid. 1. that implies for about 50% of entire lake (11.07 The potential feeding areas of A. purpurea were calculated as

Station Grids (units) Calculation Area size (m2) Don Mor Tong (DMT) 0.85 818.22 Don Seo Tai (DST) 1.00 962.61 (11,070/11.5)x0.85 Ban Chareon Suk (BCS) 0.30 288.79 (11,070/11.5)x1.00 Huai Pong Tao (HPT) 0.60 577.57 (11,070/11.5)x0.30 Don Sa Wan (DSW) 1.00 962.61 (11,070/11.5)x0.60 Noan Eee Yord (NEY) 0.80 770.09 (11,070/11.5)x1.00 A. purpurea Table 1: (11,070/11.5)x0.80 Area size in approximately at each station of the potential thefeeding lakes areas (when of applicable). However, the observation was feeding behaviors, time- spent on , a pathway, and conducted manually with limited resources that we therefore Bird observation in the field aimed to investigate on spent time for this activity only in 20 days between 7.00 frequency of visiting at the potential feeding areas within Kanongdate K. Food Supply of Purple Heron Disturbed by Local Fishing in Bung Khong Long Copyright© Kanongdate K. Lake, Thailand. J Ecol & Nat Resour 2021, 5(3): 000250. 4 Journal of Ecology and Natural Resources am and 6.00 pm during October 2010-April 2011. Mainly 2 primary data on the bird regular observation obtained = 0.6 m2 = 0.3 x 1 x 2 m and the Department of National Park Wildlife and Plant Conservationofficially from Thailand. Bung Khong Long Non-Hunting Area Office (m) 4 Area of a fish net-bag2 = width (m) x length (m) x distance 2 Fish Sampling = 100 m = 0.5 x 1 x 200 m Due to the shallow areas (water level less than 1. 5 m) , shrimps, and insect larvae were also

2. However, they were 2characterized migratory seasons around of A. the purpurea potential at Bung feeding Khong stations, Long Lake fish notsampled the focus in addition as the major at the prey same for A. station purpurea of infish this sampling study. trapsbetween and 2009/ fish net-bags 10 and were2010/11. applied A sampling in this study was duringconducted the within the area of approximately 25 m in 3 periods (early period (EP) in October; middle period Fish catch by local anglers was collected data through and counting a number of individuals including wet biomass (MP) in January; late period (LP) in April. Fish identification interviewData fromAnalysis 82 local fishers who do fishing every day. measurement were done in the field. The biomass of preys was analyzed compared with the A. purpurea (200 g/day/individual, Two fish traps at each station were placed in between A. the hypolimnion and benthic zone by covering with aquatic purpureadaily requirement to be available. of One-way ANOVA on ranks for non- plants. The mesh size is 4 cm2 and volume of a fish trap is parametricBauer [27], data which was interpreted a tool for the statistical expected analysis number in ofthis around0.14 m3 the (r2 hypolimnion x length x zone. number Some of particular traps, see species equation were 1). These traps expectedAnabas to catchtestudineus, bottom Channa feeder striata,fish and Clarias living amphibians between 2 migratory seasons of A. purpurea and sp., Notopterus, and Xenentodon cancila because they were thestudy. difference It used to of measuretotal biomass the difference of preys among in number periods of fish within and reportedexpected suchpredating as by A. purpurea in other places. Most the second migratory season. Wet weight (g) represented A. purpurea in a including Channa lucius and Channa micropeltes. day that categorized in 7 types of these fish performed economic value for local anglers including:biomass of preys that expected to be food of 3 (r2 (1) All preys (2) aboutA 100-200 fish net-bag m of with distance a volume at the of depth 157 around m x 30-50 length cm x (3) distance, see equation 2) was dragged along the shoreline (4) All fish of size between 5-15Anabas cm testudineus, Channa move freely from the surface to the hypolimnion zone. striataAll fish, ofChanna size less Lucius than, Channa5 cm micropeltes, Clarias sp., at each station. It targeted the2 small pelagic fish that likely NotopterusOnly Seven notopterusspecies of ,fish and ( Xenentodon cancila) of all traps 1 size Volume of a fish trap = πr3 x length (m) x number of (5) Amphibians = 0.14 m3 (6) Shrimps = 3.14 x 0.15 x 0.15 x 1 x 2 m (7) Insect larvae 2 2 Results Volume of a fish net-bag = πr 3x length (m) x distance (m) 3 = 157 m Purple Heron Observation = 3.14 x 0.5 x 0.5 x 1 x 200 m In this study aimed to compare available preys per area A. purpurea were observed as the that A. purpurea rather than the volume of water. Therefore, areas from numbersSix individuals decrease to of one in the MP (January) and LP (April) likely explored and spent time for foraging maximum in both migratory seasons in EP (October). The and two in LP of the second year. A pathway of A. purpurea surface.fishing gears were estimated following equation 3 and 4. The forof the foraging first migratory from 7 am year, to 6and pm decrease in Bung toKhong four Longin the Lake MP width of a fish net-bag implies the water depth of 50 cm from was shown in Figure 2. DST was the station observed the A. purpurea traps 3 Areas of a fish trap= width (m) x length (m) x number of mostvisiting frequency by (65%) follow with HPT 60%, DST 50%, DMT 15% within 20 days. The pathway Kanongdate K. Food Supply of Purple Heron Disturbed by Local Fishing in Bung Khong Long Copyright© Kanongdate K. Lake, Thailand. J Ecol & Nat Resour 2021, 5(3): 000250. 5 Journal of Ecology and Natural Resources for foraging within Bung Khong Long Lake of A. purpurea was different from other reports at the breeding grounds. It observed for 3 patterns Figure 2. Pattern 1: the bird from was habitually standing among dense vegetation of reed while then moved ahead to BCS and sometimes to DST. Then, its height to the same level of the vegetation. It normally HPT moved to small patches of floating plants nearby for a predatedswamp or alone, emergent kept hydrophytesa distance from for eachcamouflage other, andby making mostly plants nearby HPT. It moved back to HPT before DSW in observed one individual at one station. This bird was sensitive the eveningbird moved of the further day. Patternto DMT 2:or returned to the floating from DSW and directed to HPT and after that, it followed the pattern 1. Pattern 3: the bird started their to a motorboat, which used for fishing or commuting in plant in between HPT and DSW namely Lad Taae which was paddlethe lake by that moving it had away reflection to the tovicinity the noise or perching from the on distance the big the bird started from the floating approximately 50 meters or less. It also responded to the the reeds and did not move to anywhere at least within 5 lakeexcluded at DST as or a DMT sampling and then station followed in this the study. same This pathway pattern of tree. It could stand waiting for a prey quite a long time among patternthe bird 1.took During quite the long observation distance directed period for to the20 days,north we of didthe A. purpurea at NEY. Whenminutes. it sightedIn case ita prey,was unable it took to about find a10 prey, minutes it moved to rise to theup headdistance before approximately bend down one its neckmeter very away fast from to thecatch last a singlepoint. not find any

sometimesprey. The difference could be forbreaking an hour. time It took between also about first 5catch minutes and tothe get next a preywas about in the 5 minutes mouth and depending swallow. on At a leastsize of Clarias prey that sp. Channa sp. of size 13 cm were observed caught by A. purpurea during the observation. of size approximately 5 cm, Fish Sampling and other food sources

There were 40 species of fish in total caught in both 2).migratory Trichopsis years vittata (Appendices). was the highest In the number first year, caught the innumber every of fish caught less than the secondChanna year Lucius in all wasperiods the highest (Table in the middle period of the second year. Channa micropeltes andperiod Nandus of the firstoxyrhynchus year whereas were highest in LP of the second year. Kruskal-Wallis one-way ANOVA on ranks indicated that

(p<0.the average 001). numberHolm-Sidak of fish one-way per square ANOVA meter tested among the different number periods in both migratoryAnabas years testudineus, was significantly Channa different striata, Channa lucius, Channa micropeltes, Clarias sp., Notopterus, andof seven Xenentodon fish species cancila ( Figure 2: A foraging pathway of A. purpurea observed in Bung Khong Long Lake [26]. ) per square meter showing the trapssignificant was abouthigher 10- numbers 30 cm, inwhich the first was yearlarger than than the the second ones Foraging behavior of A. purpurea observed at Bung year (F = 4. 545, p < 0. 05). In addition, the size of fish from Khong Long Lake during its migratory season was not much species such as Channa Lucius. caught by a fish net- bag especially those among seven fish Migratory year EP (October) MP (January) LP (April) 2009/10 15 13 15 2010/11 35 22 27 Table 2: A. purpurea.

Kruskal-Wallis The number one-way of fish caught ANOVA at sampling on ranks stations resulted in migratory years of that the average of biomass from all prey types was not in EP resulted that the biomass of all prey types was not significantly different among periods (p<0.001). However,

Kanongdate K. Food Supply of Purple Heron Disturbed by Local Fishing in Bung Khong Long Copyright© Kanongdate K. Lake, Thailand. J Ecol & Nat Resour 2021, 5(3): 000250. 6 Journal of Ecology and Natural Resources

and LP (p < 0. 001, p < 0.004, respectively). This result shows in Figure 3. significantly different among sampling stations (p < 0.5), but was significantly different among sampling stations in MP

Figure 3: Biomass of all prey types among periods in the second migratory year of A. purpurea at Bung Khong Long Lake [26].

In the LP, Anabas testudineus has the lowest biomass counted for 16 g/m2. In addition, the studied found that the highest fromAll traps fish offor size 750 between g/m2, which 5 and 15caught cm played in EP. aThe major lowest role biomassfor biomass was from from allinsect preys. larvae The in highest all periods, biomass which of fishwas wasless g/m2 in EP; 187 g/m2 in MP; 159 g/m2 in LP). The lowest than 1 g/m2. Channa lucius was the highest biomass among biomass wasof the measured seven fish at DSTspecies station was inat EPHPT counted station for (298 26 other species counted for 345 g/m2 in EP and LP. The highest g/m2; at DMT and NEY stations in MP counted for 0 g/m2; and biomass of was measured in MP counted for at BCS station in LP counted for 0 g/m2. Biomass of the seven 160 g/m2, and of Channa micropeltes was counted for 22 g/ m2 in EP. In the MP, Notopterus notopterus and Xenentodon of the migratory season of A. purpurea is shown in Table 3. cancila had the lowest biomass counted for less than 1 g/m2. fish species and other food sources in the different periods

Biomass (wet weight: g/m2) Fish species EP (October) MP (January) LP (April) Anabas testudineus 45.50 17.79 15.67 Channa lucius 344.74 61.05 193.33 Channa micropeltes 21.50 0 0 Channa striata 31.35 160.33 53.86 Clarias sp. 81.67 17.5 38.83 Notopterus notopterus 112.67 0.06 41.48 Xenentodon cancila 0 0.02 0 Sum 637.43 256.75 343.37 Shrimp 1.72 0.67 1.21 Insect larvae 0.04 0.01 0 Amphibians 13.48 7.30 23.60 Table 3: A. purpurea Biomass of the seven fish species as a result from sum of six stations in different periods of the migratory season of

Kanongdate K. Food Supply of Purple Heron Disturbed by Local Fishing in Bung Khong Long Copyright© Kanongdate K. Lake, Thailand. J Ecol & Nat Resour 2021, 5(3): 000250. 7 Journal of Ecology and Natural Resources

Kruskal-Wallis one-way ANOVA on ranks resulted in the station (Table 4). among the periods and highest in EP (p<0. 5). Moreover, the biomass of the seven species of fish was also highest at HPT significant difference of biomass of the seven species of fish Migratory period /Weight (g/m2) Sampling Station EP (October) MP (January) LP (April) HPT 297.83 187.17 158.67 DST 26.00 15.33 96.67 DMT 97.50 0.00 23.83 BCS 65 26.17 0.00 NEY 59.83 0.00 20.83 DSW 91 18.33 43.33 Table 4: A. purpurea.

FoodBiomass supply of forthe sevensupporting fish species the at number sampling stationsof A. in differentat Bung periodsKhong Long of the Lake. migratory Total seasonbiomass of from all preys was 766.70 g/m2 suggested that it was likely to make only 4 purpurea individuals of A. purpurea 2 2 Food supply (g/m2) as categorized in the method was and 375.27 g/m for 2 individuals of A. purpurea as the maximum numbers to meet for one individual of Purple Heron (200 g/day/individual, the daily requirement in EP; 337.63 g/m analyzed by comparing with the minimum daily requirement as the maximum numbers in MP and LP, respectively. This was extrapolated in the same available for A. purpurea of the migratory season 2010/2011 as a prey. Bauer [27] (Table 5). This is an extrapolation of food direction when considered only the seven fish species only Extrapolation of number of A. purpurea by food suuply/ Periods EP (October) MP (January) LP (April) Category of prey Wet weight Wet weight Wet weight A. purpurea A. purpurea A. purpurea (g/m2) (g/m2) (g/m2) 1. All preys 4 766.70 2 337.63 2 357.27

4 750.00 2 327.00 2 347.00 (5-15 cm) 2. All fish 0 1 0 3 0 3 (less than 5 cm) 3. All fish 3 637.43 1 256.75 2 343.37 species 4. Only seven fish 5. Amphibians 0 13.48 0 7.30 0 23.60 6. Shrimps 0 1.72 0 0.67 0 1.21 7. Insect larvae 0 0.04 0 0.01 0 0 Table 5: A. purpurea due to food supply in different periods of the migratory season 2010/2011 of A. purpurea Extrapolation of the number of Local Fishing every day and this group sample was the focus of analysis. to 10.00 am and 3.00 to 6.00 pm, the same of active feeding timeThe higher observed number in A. ofpurpurea anglers have had active fished at 7.00 overlappingActive local with anglersthe foraging responded areas of to A. the purpurea questionnaires around for 82 in total. They normally fished at the shallow areas a harpoon, and a dip-net. In . addition,A common they fishing widely gear placed used by these anglers was a net, a long-lined-fish hook, a fish trap, the lake. Out of these numbers, 26 local anglers catch fish

Kanongdate K. Food Supply of Purple Heron Disturbed by Local Fishing in Bung Khong Long Copyright© Kanongdate K. Lake, Thailand. J Ecol & Nat Resour 2021, 5(3): 000250. 8 Journal of Ecology and Natural Resources several shrimp traps across the lake. The highest number of anglers (66,707 g/m2 season.about 333 With individuals regarded of to A. the purpurea amount following of fish caught the minimum by local betweenlocal anglers 3.00 fishing and 6.00 between pm. 4.00 and 10.00 was at DSW and /day), it was2/day extrapolated [27]. This to shouldbe supply be followed at HPT, NEY, DST, and DMT as same as the fishing A. purpurea (6daily individuals) requirement observed for 200 during g/m the migratory season, Hampala dispar, Notopterus notopterus, Osteochilus lini, sufficientbut the observed to support number the maximum of this bird number rather of decreased to ChannaLocal stratia, anglers Oreochromis caught fish niloticus, for at least Barbonymus 23 species goniootus, including the minimum of one individual throughout the season. It Clarias sp., and Channa Lucius. These mentioned species were to make A. purpurea caught by the anglers around 66,707 g/m2 in average per day. supplysuggested in this that lake. fishing Fish by caught local anglers per day was by likely local ananglers influence and Especially,highly frequency Notopterus of local notopterus catching. was The the seven highest fish biomass species had difficulty to access to their food Table 6. In addition, this group of local anglers also hunted thefish sameavailable prey extrapolation with A. purpurea at the such feed as area frogs were or toads. shown This in among other fish caught. The high biomass of fish caught activity was normally at night that likely caused the reduction numbersby local anglersof A. purpurea in particular in all thoseperiods seven during fish its species migratory was in number of these prey for other daytime. higher than what extrapolated to be available for observed Fish available extrapolation for Fish caught by local anglers 2 Species of fish A. purpurea (g/m /day) (g/m2/day) EP MP LP Anabas testudineus 1,000 45.50 17.79 15.67 Channa Lucius 12,575 344.74 61.05 193.33 Channa micropeltes 3,348 21.50 0 0 Channa striata 6,848 31.35 160.33 53.86 Clarias sp. 2,450 81.67 17.50 38.83 Notopterus notopterus 40,486 112.67 0.06 41.68 Xenentodon cancila 0 0 0.02 0 Total 66,707 637.43 256.75 343.37 Table 6: A. purpurea

Local fish caught and fish available extrapolation in the migratoryto several season factors of such as mortality at the origins before anglers, a vehicle such as a motor boat or even non-motor migrating to the resting areas or during the migration, which boatApart was alsofrom observed fishing gears that and disturbed catching A. frequency purpurea ofduring local has the route from Russia and Northern China to Southern foraging time in the Bung Khong Long Lake. A. purpurea was Korea, Thailand, and [6]. A. purpurea observed in sensitive with the noise making by the motor boats from this study at Bung Khong Long Lake was more likely only a migrant group rather than a resident because no breeding whereas non-motor boats did not make noise but the angler nests observed around the lake and vicinity that is in line stood10-50 onmeters and away.move Thethe noisepaddle forced had driventhe bird the to birdcamouflage to also with Robson [5]. This could be another reason for the small number of individuals observed during the migratory seasons at Bung Khong Long Lake. A. purpurea manilensis migrates camouflageDiscussion or move away from the feeding areas. to join the non-migratory populations in southeast China, Korea, Taiwan, Japan (Ryuku Islands), Pakistan, Thailand, Abundance wetlands especially for those of holding Malaysia, and to the Lesser Sunda Islands Kushlan a status as a Ramsar site normally provide enormous food and Hancock [22] but there was no report on the number for both resident and migrant birds from all over the world. of individuals visiting at each place including at Bung Khong Long Lake. The migratory route of this bird follows the route of to support the migrant birds during their migratory time other water birds in South East Asia known as the East Asian- suchBung as Khong Purple Long Herons Lake (A. is apurpurea) Ramsar site in Thailand expected Australasian Flyway EAAF [30] illustrated by Chaibhakdee observed numbers of these birds at Bung Khong Long Lake and Chaibhakdee [31]. Another cause of the decreasing in had decreased since 2004 to 2011 [8].. However, This is theprobably maximum due number of A. purpurea could be due to the decreasing trend

Kanongdate K. Food Supply of Purple Heron Disturbed by Local Fishing in Bung Khong Long Copyright© Kanongdate K. Lake, Thailand. J Ecol & Nat Resour 2021, 5(3): 000250. 9 Journal of Ecology and Natural Resources of a size of the bird’s population in Russia since 1994 [32]. A. purpurea manilensis observed at Bung Khong Long Lake was also probably decreasing even though this particular grequired in the Wittig approximately Zoo of Cottbus, 330-500g Germany. a day This per suggestedindividual thatbut subspecies has a different migratory route from other two the fishbirds to includingfeed for this A. birdpurpurea per day needs was approximatelymore food than 1,000 the subspecies [33,34]. Interestingly, the migrant groups from Russia have been reported comparatively lower than the breeders in that hypothesized the migrants have oraverage prolong of requirementfeeding time forin case feeding there per is dayscarce in thefood natural in the gradually changed to the residents [15]. Therefore, the feedingenvironments areas. Weand also likely, observed more frequent this situation predating at Bung the Khong preys decreasing in number of individuals around the world could A. purpurea A. purpurea Long Lake. Frequently observed in this study, “Whyalso influence not the thenumber maximum of individuals observed ofnumber A. purpurea of remain caught the fish of size between 5 and 15 cm which weight at Bung Khong Long Lake but the question of this study was abundantwas average at Bungof 90 Khongg that itLong needs Lake at leastas reported 3 to 4 fishin Jewyam of this size or more. This could be due to larger size of fish were not thatequally amount from theof food early supply to late periodmight notof its be migratory the cause season but the at be the reason making the birds spent considerably long at Bung Khong Long Lake?” The finding of this study explained feeding[36]. However, areas and the move difficulty around of from get one this to size other of stations fish could all with the study of Fasola and Alieri [35] that the distribution day at Bung Khong Long Lake. Other wetlands close to Bung ofdifficulty heronries to access was determinedpreys was more by foodreasonably. competition It is in with line Khong Long Lake could be alternative food sources for A. neighboring heronries which could be local anglers for the purpurea A. purpurea starts predating case of Bung Khong Long Lake. Ward and such Zahavi as [38]rice fieldsthat also [37]. observed at Bung Khong Long A. quite early morning and spending time all day until evening purpurea at the breeding areas included Rasbora aurotaenia since before 7.00 to 10.00am and between 3.00 and 6.00pm, ( RasboraAccording retrodorsalis) to Kanjanasaka , Channa [7], fish striata species ( Ophicephalusas food of whichLake. Theywas the were same comparatively time of higher active number quite of early local morning anglers striatus) , Anabas testudineus, Notopterus notopterus, Clarias A. purpurea sp., Xenentodon cancila, Alocheilus panchax and Mugil sp. to do fishing. Since the was quite sensitive to Khong Long Lake. In addition to Channa striata, C. lucius and the movement of things around [15], fishing activity by C.Five micropeltes species among were observed these fish at were this alsoRamsar observed site that at Bungwere boats caused the bird flee Pierce [39] that suggested the likely possible to be a source of food for A. purpurea as same disturbance making them difficult to access to food sources as C. striata A.[40-43]. purpurea Apart from fishing frequency, types and sizes of role of being preferable prey of A. purpurea at Bung Khong fish caught by local anglers were mostly the major preys of Long Lake, compare. These sevento other fish types species of food could sources play asuch major as that likely caused overfishing of this size and amphibians, larvae insects, etc. In addition, other species resulted in only small and medium sizes of fish available in with similar characteristics such as eels were reported for the lake [36]. Jewyam [36] reported that the2) that overfishing commonly in other breeding areas on different continents [13,16,21-23]. Bung Khong Long Lake was exceeds the capacity of natural production418,300 g/day, rate respectively)(approximately [44]. 5.36 The g/m catch per unit effort factor to make A. purpurea insufficient for local use and demands (950 g/day and2/ averageHowever, 200 specific g/individual species for[27], feeding but total might biomass not be of the feeding main meet the daily food require of for(CPUE) one ofindividual local fishing of A. by purpurea using a gill to net forage was aboutespecially 246 g/mwhen foraging. In this case, it was likely due to higher biomass day/one local angler [36] that was exceeded the availability was rather the case that influenced its shifting places of or due to abundancy of these species, made A. purpurea there were high number of local anglers and high frequency and larger size of those seven fish species than other preys of fishing at the same area. sources of A. purpurea at Bung Khong Long Lake during its frequently fed on before predated on another prey to full fill For all these reasons, the difficulty to access to food supportthe requirement. at least 4 In individuals this study offound A. purpurea that food in from early all period preys likely caused the decline in number of individuals from early ofper migratory a square meterseason provided (EP); 337.63g approximately and 357.27g 766.70 for gat that least can 2 tomigratory late period season when could considering be influenced Bung Khong by local Long fishing. Lake as It individuals in MP and LP. It suggested that the reduction in the resting and feeding area since they migrated to the place. decrease in number of A. purpurea actively feeding in the area of Bung Khong Lake was not studied at that time. This samefood available area throughout at the feeding the migratory area had season. likely influenced the isHowever, suggested the fluctuationfor further ofstudies number as of well these as birds application in vicinity of advance technologies to investigate and monitor the birds’ Bauer [27] also reported that (Ardea cinerea) behaviors in longer time.

Kanongdate K. Food Supply of Purple Heron Disturbed by Local Fishing in Bung Khong Long Copyright© Kanongdate K. Lake, Thailand. J Ecol & Nat Resour 2021, 5(3): 000250. 10 Journal of Ecology and Natural Resources

Conclusion Conflicts of Interest

This study is a part of dissertation entitled Driving that it relatively disturbed the feeding area of A. purpurea forces influencing the fluctuation of the number of Purple at BungIn conclusion, Khong Long local Ramsar fishing Site, was Thailand our finding resulted in the instudy the Herons (Ardea purpurea) at Bung Khong Long Ramsar Site, Thailand, graduated for PhD of Environmental Science (General Ecology) in 2012 from Brandenburg University betweenbird had 5difficulty and 15 cm to hadaccess rather to its more prey. important Even though for predating this bird of Technology Cottbus-Senftenberg, Germany. Some species has multi-foraging on several kinds of prey, fish of size results were presented in the virtual annual meeting ESA A. purpurea Conference 3-6 August 2020- Harnessing the ecological data fromin order other to breedingfull fill daily grounds requirement were also of observed approximately abundance 200 revolution. The presentation titled Impact of local fishing ing/ day/Bung individual.Khong Long Specific Lake speciesespecially predated Anabas by testudineus, on food supply of Purple Heron in Bung Khong Long Lake, Channa striata, Channa lucius, Channa micropeltes, Clarias Thailand. sp., Notopterus notopterus, and Xenentodon cancila which were also reported as major food of this bird in the south Acknowledgements of Thailand at its breeding ground. However, a number of A. purpurea decline of its number of individuals from early to late period Dr. rer. nat. Habil. Gerhard Wiegleb and my co-supervisor PD fish fed by seem not to be a case to explain the Dr. rer.I would nat. habil. like to Udo express Bröring my forgratitude their advice to my andsupervisor all supports Prof. sources was rather the hint of that situation. In this study we throughout the study. It is very thankful to Dr. Seth Nii- of the migratory season. Wet weight (g) of fish and other food Annang for all suggestions and grammar correction. I would 5-15 cm and found that this food available likely support for 4 individualsmeasured biomass of A. purpurea of prey in fromearly periodall types (EP) mainly of the fish migratory of size season and for 2 individuals in mid and late periods (MP, LP). Bumrungsaksanti,like to express my Mr.sentimental Tongdee Wongkumkaew,and appreciate toMr. all Boontom officers A. purpurea observed Prompanhaow,from Bung Khong and Long from Non-Hunting other colleagues Area office: and Mr.friends: Chareon Mr. during the study was 6 individuals in EP and became left only Wanlop Preechamart, Miss Apiradee Hanpongkittikul, Mr. Meanwhile, the maximum number of Nared Namueangrak, and Miss Anocha Pichaisiri. as one factor that drove these birds moved out of the lake. 1 in LP, thus insufficient food available was relatively clear References In addition to the insufficient food available at the feeding 1. 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