山階鳥学誌 (J. Yamashina Inst. Ornithol.), 35: 155-158, 2004

The Diet of Adult and Nestling Sickle-billed Vangas Falculea palliata, a Species Endemic to Madagascar

Masahiko Nakamura*, Takayoshi Okamiya* and Satoshi Yamagishi**

Abstract. The Sickle-billed Vanga Falculea palliata forages by probing its long and slender bill into cracks on the trunks and branches of trees. To determine the diet of adult and nestling Sickle-billed Vangas and the kinds of prey obtained with this foraging technique, six nests in the Ankarafantsika Strict Nature Reserve, western Madagascar, were observed during the November to December nestling periods in 1999 and 2000. Diet was investigated by direct observation. Of the 41 items of prey identified (out of 68 total prey items) in adult Sickle-billed Vangas, crickets, cockroaches, spiders, and grasshoppers constituted 29.3%, 19.5%, 17.1%, and 12.2%, respectively, of the prey items. These four groups together accounted for 78.0% of the identified prey. Parents delivered 1,180 prey items to the nestlings. The most numerous food items were crickets, accounting for 41.6% of 262 identified prey, followed by cockroaches (21.4%) and grasshoppers (15.6%). These three groups together accounted for 78.6% of the identified prey. Sickle-billed Vangas never foraged on the ground but preferred dead trees of five metres or higher for foraging, and it is thus highly probable that all prey items were of arboreal origin. Arboreal cockroaches inhabit holes and cracks on dead trees and branches, and it is likely that Sickle-billed Vangas capture them primarily using the probing technique. Key words: Arboreal cockroach, Diet, Foraging technique, Madagascar, Sickle- billed Vanga. キ ー ワ ー ド:樹 上 性 ゴ キ ブ リ,餌,採 食 方 法,マ ダ ガ ス カ ル,ハ シ ナ ガ オ オ ハ シ モ ズ.

The Sickle-billed Vanga Falculea palliata belongs to the Vangidae, a family endemic to Madagascar (Milon et al. 1973, Langrand 1990, Yamagishi et al. 2001). This species has a very long and slender bill, and forages by probing the bill into cracks on trunks and branches of large trees (Langrand 1990, Yamagishi & Eguchi 1996, Eguchi et al. 2001). This foraging technique is unique, not only among vangids (Yamagishi & Eguchi 1996), but also among passerines in Madagascar (Eguchi et al. 1993). Sickle-billed Vangas forage for large insects (Coleoptera and Orthoptera), spiders, snails, and small arboreal lizards, such as Phelsuma spp. (Appert 1970, Langrand 1990). However, there are insufficient data on the diet of Sickle-billed Vangas and on the kind of prey obtained with probing technique. This paper presents the diet of adult and nestling Sickle-billed Vangas during the breeding season. This study was conducted at the Ampijoroa Forest Station (16. 15'S, 46. 48'E, ca. 200m above sea level) in the Ankarafantsika Strict Nature Reserve, located in western

Received 22 October 2003, Revised 9 December 2003, Accepted 19 December 2003. * Laboratory of Animal Ecology , Department of Biology, Joetsu University of Education, 1 Yama- yashiki-machi, Joetsu-shi, Niigata 943-8512, Japan. ** Yamashina Institute for Ornithology , 115 Konoyama, Abiko, Chiba 270-1145, Japan.

155 156 Masahiko Nakamura, Takayoshi Okamiya and Satoshi Yamagishi

Table 1. List of prey items of adults and nestlings of Sickle-billed Vangas. Prey items were recorded during the nestling period at six nests. Mean body size ± SE is given in cm.

Madagascar, from November to December, in 1999 and 2000. The eastern part of the reserve included a small village, a forest station, and a campsite, around which large eucalyptus and Hura crepitans (Euphorbiaceae) trees were planted. Six nests were observed for a total of 207 hours over 38 days during the nestling period and food delivered from parents to nestlings were recorded. After parents fed the nestlings, they sometimes foraged near the nest. The diet of adults and nestlings was investigated by direct observation, between O500 and 1100, using a 20×spotting scope, from a vantage point that allowed a good view of the nest (5-15m). The size of prey relative to bill length (average length=60.9mm, see Eguchi et al. 2001) was noted. For adults, foraging location (tree trunk or branch), the condition of the foraging tree (dead or alive), and the height at which foraging occurred, were recorded. Sixty-eight items of prey of the adult Sickle-billed Vangas were determined. Of the 68 items, 57.4% (39) were invertebrates, 2.9% (2) were vertebrates, and 39.7% (27) were unidentified (Table 1). Unidentified prey items were too small to classify. Crickets were the main prey, accounting for 29.3% of 41 identified prey (Table 1). Cockroaches, spiders, and grasshoppers accounted for 19.5%, 17.1%, and 12.2% of the 41 identified prey, respectively. These four groups together accounted for 78.0% of the identified prey. The prey size ranged from 10 mm (e.g. a spider) to 70 mm (e.g. a gecko). Prey included The Diet of Adult and Nestling Sickle-billed Vangas Falculea pal/iota 157 two Madagascar day geckos, Phelsuma madagascariensis. Adult Sickle-billed Vangas swallowed all prey whole. Sickle-billed Vangas never foraged on the ground but preferred trees of 5 m or higher for foraging (61 of 68 prey). Foraging occurred on dead trees 52% of the time. However, Sickle-billed Vangas often foraged on dead parts of living trees, and the true percentage of foraging on dead substrates was 68% of all observations. Trunks and branches made up 49% and 51 % of foraging locations, respectively. These results were similar to foraging observations taken during the non-breeding season (Eguchi et al. 2001). Parents delivered 1,180 prey items to the nestlings. Of these items, 21.2% (250) were invertebrates, 1.0% (12) were vertebrates, and 77.8% (918) were unidentified (Table 1). Like the food items of adults, the most numerous food items were crickets, accounting for 41.6% of 262 identified prey items (Table 1), followed by cockroaches (21.4%), and grasshoppers (15.6%). These three groups together accounted for 78.6% of the identified prey. The prey size ranged from 10mm (e.g. a termite) to 60mm (e.g. a gecko). When nestlings were small (from hatching to day 7), prey groups could not be identified because the nestling diets were too small. Parents delivered vertebrates to nestlings of day 8 or older. Of seven gecko prey items, at least four were Madagascar day geckos. It has been shown that the Hook-billed Vanga Vanga curvirostris delivers pieces of small vertebrates (e.g. gecko, chameleon, and bird) to its nestlings (Rakotomanana et al. 2001). The Sickle-billed Vanga, however, fed the entire body to nestlings, and the nestlings swallowed the prey whole. The origin of the food delivered by parents to nestlings was not determined. However, because Sickle-billed Vangas in this study area were never observed foraging on the ground but preferred trees of 5m or higher for foraging, all prey were likely to be arboreal. Sickle-billed Vangas often capture prey by probing with their bills into the holes and cracks of dead tree branches (Eguchi et al. 2001). The Orthoptera, including arboreal crickets and grasshoppers, are found on leaves or branches, and the primary habitat of Madagascar day geckos, chameleons, and lizards (Oplurus cuvieri) is the trunks and branches of trees (Randriamahazo 1999), although nocturnal geckos (e.g. Blaesodactylus cf. Sakalava) hide in the cracks of tree trunks during the daytime (Mori et al. 2001). In contrast, there are many species of cockroach in Ampijoroa, and the arboreal cockroaches (e.g. Gromphadorrhina spp., Elliptorhina spp., and Periplaneta americana) inhabit the holes and cracks of dead trees and branches (H. Rakotomanana & A. Mori unpublished data). Thus, it is likely that Sickle-billed Vangas capture arboreal cockroaches using the probing technique. Acknowledgments We would like to express our appreciation to the director, A. Randrianjafy, and the staff of PBZT, for their cooperation in the present study. Our thanks are also due to the staff of ANGAP, for the use of the facilities at Ampijoroa Forest Station. We would also like to thank Drs. A. Mori, H. Hasegawa, T. Mizuta, S. Asai, and H. Rakotomanana, and Mr. I. Ikeuchi, for their assistance and advice in the field. We are grateful to Drs. K. Eguchi and S. Asai for their helpful comments on the manuscript. This study was 158 Masahiko Nakamura, Takayoshi Okamiya and Satoshi Yamagishi

supported by a grant under the Monbusho International Scientific Research Program (Field Research, No. 11691183).

References Appert, O. 1970. The Biology of the Vangas of Southwest Madagascar (Zur Biologie der Vangawurger [Vangidae] sudwest Madagaskars). Ornithologischer Beobachter 67: 101-133. (in German) Eguchi, K., Yamagishi, S. & Randrianasolo, V. 1993. The composition and foraging behaviour of mixed-species flocks of forest-living birds in Madagascar. Ibis 135: 91-96. Eguchi, K., Amano, H. & Yamagishi, S. 2001. Roosting, range use and foraging behaviour of the Sickle-billed Vanga, Falculea palliata, in Madagascar. Ostrich 72: 127-133. Langrand, O. 1990. Guide to the Birds of Madagascar. Yale University Press, New Haven and London. Milon, P., Petter, J-J. & Randrianasolo, G. 1973.Oiseaux, Vols. 1 and 2. Faune de Madagascar 35: 1-263. (in French) Mori, A., Ikeuchi, I. & Hasegawa, M. 2001. Reptiles and amphibians of Ampijoroa, Ankarafantsika Strict Nature Reserve, a dry forest in northwestern Madagascar. In Ecological Radiation of Madagascar Endemic Vertebrates-with special respect to coevolution between birds and reptiles. (eds. S. Yamagishi & A. Mori), pp. 86-92. Report submitted to the Japanese Government, Kyoto. Rakotomanana, H., Nakamura, M. & Yamagishi, S. 2001. Breeding ecology of the endemic Hook-billed Vanga, Vanga curvirostris, in Madagascar. Journal of the Yamashina Institute for Ornithology 33: 25-35. Randriamahazo, H. 1999. Reptiles of Madagascar. In The Animals of Madagascar-its wonderful adaptive radiation-. (ed. S. Yamagishi), pp. 168-212. Shokabo, Tokyo. (in Japanese) Yamagishi, S. & Eguchi, K. 1996. Comparative foraging ecology of Madagascar vangids (Vangidae). Ibis 138: 283-290. Yamagishi, S., Honda, M., Eguchi, K. & Thorstrom, R. 2001. Extreme endemic radiation of the Malagasy vangas (Ayes: Passeriformes). Journal of Molecular Evolution 53: 39-46.

マダガスカル固有 ハ シナガオオハ シモズの成鳥 と雛 の餌

マ ダ ガ ス カ ル 島 固 有 種 の ハ シ ナ ガ オ オ ハ シ モ ズ(Falculea palliata)は,細 長 く 曲 が っ た嘴 を

枯 れ 木 の 幹 や 枝 の 隙 間 に さ し込 み,そ の 中 に 潜 む 餌 を つ ま み 出 して 採 食 す る 。 本 種 は こ の 採 食 方法を用いて何を食べているのだろうか。ハシナガオオハシモズの食性を明 らかにするため, 1999年 と2000年 の11月 か ら12月 に マ ダ ガ ス カ ル 西 部 地 域,ア ン カ ラ フ ァ ン ツ ィ カ 厳 正 自 然 保 護 区 に お い て 育 雛 期 に あ た る6巣 を 調 査 し,雛 と 親 の 餌 内 容 を 直 接 観 察 し た 。 成 鳥 が 捕 ら え た68個 の 餌 の う ち41個 を 識 別 で き,そ の 内 訳 は コ ロ ギ ス 類,ゴ キ ブ リ類,ク モ 類 と キ リギ リ ス 類 が そ れ ぞ れ29.3%,19.5%,17.1%,12.2%で あ っ た 。 こ れ ら4グ ル ー プ は 全 体 の78.0%を 占 あ た.親 は 雛 に1,180個 の 餌 を 給 餌 し た 。最 も 数 の 多 か っ た 餌 は コ ロ ギ ス 類 で 識 別 で き た262 個 の 餌 の41.6%を 占 め,つ い で ゴ キ ブ リ類(21.4%),キ リ ギ リ ス 類(15.6%)の 順 で あ っ た 。 こ れ ら3グ ル ー プ は 全 体 の78.6%を 占 め た 。 ハ シ ナ ガ オ オ ハ シ モ ズ は 地 上 で 採 食 す る こ と は な く,5m以 上 の 枯 れ 木 を 好 ん だ 。 そ れ ゆ え,す べ て の 餌 は 樹 上 性 と 考 え られ る 。 樹 上 性 ゴ キ ブ リ 類は枯れ木の幹や枝の割れ目に生息するので,ハ シナガオオハシモズは主に樹上性ゴキブリ類 を 枯 れ 木 の 割 れ 目 か らつ ま み と っ て い る と考 え た 。

中村雅彦 ・岡宮隆吉:上 越教 育大学生物 学教室動物 生態学研 究室.〒943-8512新 潟県上 越 市山屋敷町1番 地. 山岸 哲:(財)山 階鳥類研究所.〒270-1145千 葉県我孫子市高野 山115.