Wintering Ecology of White Wagtail Motacilla Alba Lugens in the Middle

20 山階鳥研報第9巻第1号(No.48)

Wintering ecology of White Wagtail Motacilla alba lugens

in the middle stream of Tama River

Michihito WATANABE* and Naoki MARUYAMA**

White wagtail (Motacilla alba LINNAEUS) widely distributed in Palaearctic, is subdivided into more than ten subspecies. Although, of such subspecies, M. alba alba and M. a. yarreillii, both European subspecies, have been ecologically and ethologicaly studied (GOODWIN 1950, GREAVES 1941, HARTLEY 1946, WHITE 1950, RENDAHL 1967 and ZAHAVI 1971a & b), few deal with Motacilla alba lugens which breeds from South Kamchatka to North Honshu of Japan, and which winters in South Honshu, Formosa, and South China. Accord- ingly, the ecological study on this subspecies may contribute towards the analysis of life-mode of this species. We intend to report on the wintering ecology of this subspecies, Motacilla alba lugens, in the middle stream of Tama River, flowing south of Kanto district.

Study Area

The study area was situated at the upper stream side of the railroad bridge of National Chuo Line in the middle stream of Tama River, flowing south of Kanto district from Kanto Mountains to Tokyo Bay (Fig. 1). In most of the riverside, submerged riverside grassland, mainly consisting of Miscanthus sinensis and M. sacchariflourus, dominated. Through this grassland, a drainage flows northerly from a sewage to Tama River. On the shore of this dirty and stagnated sewage drainage, muddy and gravel grounds were scattered here and there and provided feeding sites of white wagtail (Fig. 2). On the other hand, Zanbori River, a branch of Tama River, flows about 700m north of the sewage drainage. Concrete bank protection and crowded houses near the stream prevented growth of grass on this riverside. Observations were carried out in the area of about 6 ha along the sewage drainage and in a part of Zanbori River.

Methods and Periods

White wagtail were observed from the six vantage points for observation, A～F, established along the sewage drainage from dawn till dusk. In such observations, telescopes (×25,

×40) and binocular (×8) were used. Their behaviors and moving traces were recorded into

* Fuji-gakuen High School , Fujiyoshida City, Yamanashi Prefecture ** Faculty of Agriculture, Tokyo University of Agriculture and Technology, Fuchu, Tokyo

(20) 昭和52年(1977)3月 Wintering ecology of White Wagtail 21

Fig. 1. Study area.

Fig. 2. Distribution of vegetation, muddy ground and grave ground in the study area. Alphabets in figure represent the locations of the vantage points, used in observation.

(21) 22 山階鳥研報第9巻第1号(No.48)

the maps of 1:1,000. It was possible to distinguish between individuals of white wagtail by their various shaped, black breast-plumages, at least in a observation day. This individual distinction method was carried out from January 20, 1973. Furthermore, by their plumage colorations, they were classified into three plumage patterns as I, II and III (Fig. 3). The coloration pattern I represents individuals with the black head and the black back. The pattern II represents individuals with the black head and the gray back. The pattern III represents individuals with the gray head and the gray back. The intermediate patterns between such three patterns were also observed and were distinguished as "I-II" and "II-III". In observations, territories were distinguished and called by observation dates and those locations, respectively. For example, "territory 3JA" represents a territory observed from the vantage point A on January 20, 1973, and "territory 4MC" represents a territory observed from the vantage point C on March 20, 1974. Observations in the main area, the sewage drainage, were carried out seven times as follows: November 11, December 2, 1972, January 20, March 6, October 9, December 28, 1973, and March 20, 1974. In the sub- Fig. 3. Three plumage colorations area, Zanbori River, observations were carried out as of white wagtail. follows: March 6 and December 28, 1973.

Results and Discussion

Territory establishment Fig. 4 indicates moving traces of white wagtail on October 9, 1973, immeadiately after

the arrival of the birds in Tama River. In usual year, the first birds arrive in early October. Most of the birds conspicuously flew about long distance in single in the area and took food on muddy and gravel grounds along the drainage and around stones scattered on

water. Furthermore, we observed little site-attachment and few aggressive behaviors among the

birds. While, a few pairs of the birds tried attachment to a certain area including the feeding sites. However, those areas could not be considered as territories. As a result, on this day, it was difficult for us to recognize territory establishment of white wagtail in the study area. On November 11, 1972, about a month after from the first arrival of the birds, white

(22) 昭和52年(1977)3月 Wintering ecology of White Wagtail 23

Fig. 4. Moving traces of white wagtail on October 9, 1973. Hatching represents the feeding sites of white wagtail.

wagtail behavior was different from the one in the last month. Most of the birds showed intensive attachment in single or pair to the fixed areas including more than two feeding sites. Those fixed areas were slightly overlapped one another and were considered as either territories or undefended feeding ranges. Fig. 5 indicates territories obserbed from this day till the start of spring migration. Numbers of territories were from 6 to 8, and the territory sites were also stable through a wintering season. It was impossible to convince that the same birds lasted to occupy the same territories through the wintering season.

According to the above, territories and undefended feeding ranges of the birds were probably established till November.

Territory and territorial behaviors Fig. 6 indicates the points where territorial birds attacked intruders. This repulsive behavior was one of the territorial behaviors, by which the territorial birds drove away intruders out of the areas. Accordingly, such defended areas could be exactly called territories. Those territorial behaviors were classified into the following five patterns.

Confronting-Two birds occasionally confronted each other at a distance of 20-30cm near

(23) 24 山階鳥研報第9巻第1号(No.48)

Fig. 5-a

(24) 昭和52年(1977)3月 Wintering ecology of White Wagtail 25

Fig. 5-b

Fig. 5. Locations of white wagtail territories observed in the wintering periods, 1972-1973 and 1973-1974. A. Nov. 11, 1972 B. Dec. 2, 1972 C. Jan. 20, 1973 D. Mar. 6, 1973 E. Dec. 28, 1973 F. Mar. 20, 1974 A and a part of B was described in moving traces and others were described in activity loci.

(25) 26 山階鳥研報第9巻第1号(No.48)

Fig. 6. Points where territorial birds attacked intruders, on December 2, 1972 and January 20, 1973. Enclosed lines represent the borders of territories. △Fight ▲Chase □Confronting ■Threat ●Alert →Moving traces of dominants →Moving traces of intruders

(26) 昭和52年(1977)3月 Wintering ecology of White Wagtail 27

Fig. 7. Confronting posture of white wagtail.

Fig. 9. Fighting postures of white wagtail.

Fig. 10. Wing quivering display Fig. 8. a-d Threat postures of white wagtail. of white wagtail.

Fig. 11. Vertical flight display of white wagtail.

(27) 28 山階鳥研報第9巻第1号(No.48) the border of their territories (Fig. 7). Most of them were neighbouring territory occupants. Threat-In confronting, one bird threatened another. It frequently resulted in breaking the confronting situation. In the case where confronting still continued, chase was acted as stated later. Threatening postures were classified into four patterns as follows; (1) the bird looked upward with the tail upward and sang with the slightly opened bill (Fig. 8-a), (2) it flew up vertically about 50cm height above the ground and alighted at the same place (Fig. 8-b), (3) it flew over the head of opponent and returned back to the same place (Fig. 8-c), and (4) it flew up vertically and fluttered 50-100cm height above the ground (Fig. 8-d). Chase-It was a behavior that territory occupants pursued the intruders, most of which repeated the sound "pipit, pipit". Fight-It was a behavior that two struggling birds tangled together in the air with the bills and the feet. It also occurred before and after chase (Fig. 9). Alert-They frequently alighted on stones or on sand banks in the stream, or perched on dead trees, and seemingly looked round for intruders. Territory occupants did not always last to stay in their territories all day long. They sometimes showed long flights out of their territories. Most of those flight directions stably pointed to Zanbori River flowing northerly, and a few pointed to the main stream of Tama River, flowing southerly. For example, the occupant of the territory 3MB on March 6, 1973, showed the round trips to Zanbori River and to a cultivated land, situated between the drainage and Zanbori River. This individual only took food but did not occupy any territory in the both areas. Also in Zanbori River, a bird showed the round trip to a ajacent cultivated land. Such prominent long flights were also taken by most of the occupants, such as 2DA, 2DB, 2DG, 3JA, 3JB, 3JG, 3MA, 3MB, 3MG, 3DE, 4MA and 4ME. According to the above, at least in the study area, the territory occupants seemingly held one or more undefended feeding sites out of their territories.

Territorial birds and pairing behaviors In territory occupation, two cases were observed: firstly, a territory belonged to a

Table 1. Numbers of territories occupied by both pair and single bird.

(28) 昭和52年(1977)3月 Wintering ecology of White Wagtail 29

bird, and secondly, it belonged to two birds. However, such cases where more than three birds occupied the same territory were not observed (Table 1). Between two birds, occupying the same territory, the following pairing behaviors were observed. In approaching each other, one bird raised up the tail, and put down the wings and quivered them (Fig. 10). This behabior was occasionally accompanied by the sound "churi- churi". It seemingly corresponds to the intense situation of the appeasement display of Motacilla alba alba, reported by ZAHAVI (1971b), and is striking similarity to the sexual display, reported by HARTLEY (1946). Also, WHITE (1950) reported on the similar display in more intensive situation. In those reports, females show such displays. Furthermore, such behaviors resembled to the female posture of Japanese wagtail (Motacilla grandis) and gray wagtail (M. cinerea) in copulation, reported by HANEDA & ICHIKAWA (1946) and HANEDA & SHINODA (1969). According to the above, also in white wagtail, females seemingly showed the "wing quivering display". Another behavior observed between pair-making birds of white wagtail was "vertical flight display" that one bird flight up about 50cm height above the ground and held the body in vertical with the tail downward (Fig. 11). We also observed a bird flying up four times at rapid intervals. This vertical flight display exactly resembled to the "courtship display" shown by the males of white wagtail, reported by HARTLEY (1946), and to the male behaviors of Japanese wagtail (Motacilla grandis) and gray wagtail (M. cinerea) in copulation, reported by HA- NEDA & ICHIKAWA (op. cit.) and by HANEDA & SHINODA (op. cit. ). Accordingly, also in white wagtail, the vertical flight display was shown by the males. Such behaviors were closely related to the plumage colorations of the birds. The wing quivering display was shown by the bird II, II-III and III, and was accepted by the bird I, I-II and II. While, the vertical flight display was shown by the bird I and was accepted by the bird II and II-III. According to the above, it seemed that the plumage pattern I and I-II indicated male, that the pattern II-III and III indicated female, and that the pattern II indicated either sex. Further, it is possible to say that a territorial pair consisted of both sexes. ZAHAVI (op. cit.) has already reported that Motacilla alba alba make such winter pairs. The pair-making males were usually more aggressive than the females. When the intruder was only one, the territorial male usually made defence of territory against it. On the other hand, when they dominated over the territorial male, the territorial female also defended . ZAHAVI (op. cit.) also stated that in established pairs of M . alba alba, females continue to defend the territory against any intruding bird, male or female . The aggressive territorial male not only drove away intruders , but also frequently and slightly attacked the female of the same territory. In this case, the female usually calmed

(29) 30 山階鳥研報第9巻第1号(No.48) down the male by the wing quivering display. Those territorial pair bonds were not necessarily stable in a day. For example, on March 6 and October 9, 1973, a territorial bird in pair changed its companion for another near v. p. F. ZAHAVI (op. cit.) stated that many pair bonds of Motacilla alba alba lasted for weeks or months but quite often a female intruded into a neighbouring territory and appeased the male of the territory. Pair-making was observed on March 20, 1974. At 0:22 p. m., a male bird with the plumage pattern I intruded into a territory, which had been already occupied by a female with the plumage pattern II-III from the beginning of observation at 6:15 a. m.. The territorial female showed not any aggressive behavior but wing quivering display. This male took food on the ground and showed vertical flight display. Then, it frequently visited this territory and took food for long hours with the territorial female. This situation lasted till roosting. For this duration, wing quivering display was shown three times and vertical flight display was shown six times.

Wanderer "Wanderers" were also observed . Coming over out of the study area, and trying to intrude into territories, they accepted one-side attack by territorial birds or flied away before it. Most of them were in single.

Therefore they usually could not occupy territories and wandered over the territories. How- ever, at the first opportunity, they may establish their territories, as the following case.

At 10:20 a. m., March 6, 1973, one of the wanderers with II-III plumage pattern came over the vacant area without any territory near v. p. E and competed with a pair of the neighbouring territory. Later on it succeeded in establishing its own territory.

Observation-area curve and territory size In our study area, the observation- area curve of white wagtail frequently bent upward at the end, because not a few birds restlessly flied about here and there before roosting. Excluding those bends, we classified the observation-area curves (Appendix 1-4) into three types according to their shape resemblances. The first type presents resemblance to Fig. 12. Three types of observation-area curves of white wagtail. the sigmond curve and becomes level as A. Sigmoid curve B. Cubic curve number of the activity loci increases C. Straight line

(30) 昭和52年(1977)3月 Wintering ecology of White Wagtail 31

(Fig. 12-A). The second type presents resemblance to the cubic curve. As number of activity loci increases, it approaches near to level and then bends upward again (Fig. 12-B). The third type presents resemblance to the straight line (Fig. 12-C). Those types of observation-area curves seemingly represent the activity situations of the birds. The first type represents stable situation, where the birds stay in a certain area. On the other hand, the second type represents temporal stable situation where the birds stay in a certain area, and begin again to expand their activity ranges. The third type represents unstable situation where the birds last to expand their ranges or does not stay in a certain area. Stability of the observation-area curve varied with the season. As shown in Table 2, on December 28, 1973, most of them represented the third type of the straight line. How- ever, on January 20, 1973, all of them represented the first type of the sigmoid curve. On the contrary, on March 6, 1973, five of seven cases represented the third type. And on March 20, 1974, every case but one represented either the second type or the third type.

Table 2. Occurence frequencies of three types of the observation-area curves in white wagtail.

The above types of observation-area curves were not directly related to the sizes of feeding sites in territory and the rates of territory fixing (per cent of the territory-staying hour against the observation hour, Table 3). Accordingly, seasonal activity of this species, indicated by the observation-area curve, seemingly related to the migratory physiology. In measurements of territory sizes, ODUM & KUENZLER (1955) indicates that a one per cent level, that is, a point on the smoothed curve (the observation-area curve) beyond which each additional observation will produce less than one per cent increase in the area, appears to be a good, practical point to use. In our study, since the territorial birds were not always to show the stable situations in the observation-area curves, we used, however, a point before the roosting bend in territory size measurements. In November and December, 1972, when the individual distinction method was not carried out, territory sizes were got by connecting the outermost points of activity loci or moving traces of the individuals, considered as the occupants by their territorial behaviors. The territory sizes, got by the above

(31) 32 山階鳥研報第9巻第1号(No.48)

Table 3. Rates of territory fixing in white wagtail. (%)

Table 4. Sizes of winter-territories of white wagtail in m2.

methods, were shown in Table 4. During the period of January-March, 1973, average territory size was 3,364m2 and its standard deviation was 2,941m2. In the next winter 1973-1974, the average was 4,519m2 and its standard deviation was 5,001m2. However, both were not significantly different (t-test, p>0.1).

Feeding sites in territories The birds spent most of the time in territories in taking food. Their feeding ranges restricted to the surface of gravel and muddy grounds, the shallow ground cover, and the

(32) 昭和52年(1977)3月 Wintering ecology of White Wagtail 33

Fig. 13. Schema of feeding ranges of white wagtail. air around the perches on the water, without vegetation (Fig. 13). Feeding sites were the areas, got by connecting the outermost points where the birds took food, except for grasslands where they did not take food. Summed area of the feeding sites in the study area exceedingly varied annualy and seasonably (Table 5). This variation was related to the abundunce of water; if it increased, the gravel and muddy grounds, the important feeding sites, would be sunk below the water. However, in response to this variation, little changes were seemingly observed in both the

Table 5. Sizes of feeding site of white wagtail in m2.

(33) 34 山階鳥研報第9巻第1号(No.48) territory sizes and the rates of territory fixing. Degree of activity in a given area could be indicated by number of activity loci (DICE & CLARK 1953). We divided the study area by the grid square of 40m2 and got number of activity loci in each grid square. (Appendix 5) Number of the activity loci was significantly higher in the feeding site than out of it

Table 6. Numbers of the grids in activity density of white wagtail in and out of the feeding site.

(34) 昭和52年(1977)3月 Wintering ecology of White Wagtail 35 through the study periods (Table 6). Also in October 1973 when territories were unestab- lished, 76 (66%) of 109 loci were situated in the smallest feeding site of 453m2. As the above, in every case, the activities of the birds were clearly concentrated in feeding sites.

Roosting The territory occupants suddenly began to fly high before sunset and left the study area. Those flights were truly higher than those in the daytime, and were seemingly one of the roosting behaviors.

Table 7. Occurence frequencies of roosting flight directions of white wagtail.

Table 7 indicates the direction of roosting flight from and through the study area, and their numbers. In every observation, most of them flew north, but none flew west. Fig. 14 indicates times and numbers of the roosting flights. In October and December, the occurences of roosting flights were concentrated half an hour before and after sunset, and its peak appeared immeadiately before or after sunset. In January and March, the roosting flight began to occur one hour or more before sunset and its peak also appeared 20-30 minutes before sunset. In this tendency, we found little difference between the territory occupants in the study area and the passing birds through it. The birds which began roosting flights immeadiately before and after sunset, seemingly flew directly into the roosts. On the other hand, in the birds which started for the roosts half an hour or more before sunset, the following three cases were considered. (1) They directly flew into the roosts. (2) They took food on the way before roosting, and then flew into the roosts. (3) They gathered in a certain place near the roost, and then flew into the roost.

(35) 36 山階鳥研報第9巻第1号(No.48)

Fig 14. Times and numbers of the roosting flight of white wagtail. The time of sunset is shown by arrow and broken line. The parts of grid represent the numbers of territory occupants.

ZAHAVI (1971a) reports that Motacilla alba alba fly into the communal roost from one or more gathering places near the roost or up to a few hundred meters away in Israel. GREAVES (1941) also reported the communal roost of this species in winter in Cairo district. WON et. al. (1966) reports the communal roost of M. alba leucopsis in summer in Korea. Also in M. alba lugens, the communal roosts in winter were discovered at Yahagi Bridge, Okazaki-city, Aichi Prefecture (YOSHII & HASUO 1969, YOSHII et. al. 1970), at Suido Bridge of Tama River (Japan Avian Soc. 1974), and at Tamagawa-oohashi of Tama River (SUGIMORI pers. comm.). On the other hand, GREAVES (op. cit.) stated that Motacilla

(36) 昭和52年(1977)3月 Wintering ecology of White Wagtail 37 alba roosted in smaller numbers in trees near Gezira Sporting Club in Cairo district.

Interspecific relations to other birds Bird species, which bore relations in behavioral aspect to white wagtail, were Japanese wagtail (Motacilla grandis), gray wagtail (M. cinerea), water-pipit (Anthus spinoletta), and tree-pipit (A. hodgsoni) in Motacillidae, and, in other families, meadow bunting (Emberiza cioides), skylark (Alauda arvensis), kestrel (Falco tinnunculus), and bull-headed shrike (Lanius bucephalus). Japanese wagtail, considered as a closely related species of white wagtail by speciation, seemingly resembled in food habit to white wagtail. In the study area, two birds of this species were observed and their activities were concentrated in the vicinity of v. p. A and in the drainage near v. p. F in the winters of 1972-1973 and 1973-1974. In both areas, they were driven away by the territory occupants of white wagtail. On the other hand, its contrary relations were also observed. Further, they occasionally showed little concern. Such balanced relations between them were seemingly caused by the incomplete territory establishment of white wagtail. However, Japanese wagtails usually did not try to intrude into the area from v. p. B to v. p. F where white wagtails completely established territories; even if they tried to intrude into the territories of white wagtails in this area, they always accepted one-side attack by territorial white wagtails. In this case, most of chases showed long flight. Gray wagtails appeared in the same places. Its appearance, however, was rare, comparing with the case of Japanese wagtails. Accordingly, their usability of feeding sites were severely restricted by time and place, when and where white wagails and Japanese wagtails were absent. As compared with the above two species, water pipit was abundant in every observation over the study area. Usually, they aroused weak concern of white wagtails. In most cases, approaching toward white wagtails, they were driven away 2-3m out of feeding sites by white wagtails. It was differ from the cases of Japanese wagtails and gray wagtails with long flights out of territories. Since tree pipit was rare in the study area, their interspecific relations to white wagtails were only observed twice. Both were slight chases as the cases of water pipits. In addition to the above four species of Motacillidae, chases of white wagtails after a meadow bunting and a skylark were also observed only once, respectively. On November 11, 1972, one of white wagtails chased after a kestrel in the study area. TINBERGEN (1956) stated the communal aggression of wagtails against a sparrow hawk, but its occured season was unknown. In breeding season, the communal and one bird aggressions of white wagtails against kites and crows, considered as predators, were occasionally observed in Hokkaido (WATANABE unpublished). The chases after bull-headed shrikes were also observed five times in the study area.

(37) 38 山階鳥研報第9巻第1号(No.48)

For example, on March 6, 1973, a shrike was chased about 10m. However, it was not

evident that the bull-headed shrike was truly one of the predators of white wagtail . According to the above, the repulsive behaviors of white wagtail to the closely related

species in Motacillidae were probably caused by the resemblance of their life-needs. White wagtail was considered as the dominant in Motacillidae at least in the study area in winter. The chases after meadow buntings and skylarks were seemingly caused by the similar reason to the chases of Motacillidae. However, it was worthy to indicate that those repulsive behaviors were qualitatively different from the one against the predators.

Summary: We studied on the wintering ecology of Motacilla alba lugens, one of the sub- spesies of the white wagtail, in the area of about 6ha, situated at the middle stream of the Tama River, Tokyo, during the periods of November 1972 to March 1973 and October 1973 to March 1974. Winter territories and undefended feeding ranges were established till November and were maintained through winter. Those territories were occupied by one or two birds, consisting of both sexes. Sexes were checked by their behaviors such as "wing-quivering display" and "vertical flight display" . Wanderers without territories tried to intrude in singles. Territorial behaviors against intruders were classified into five patterns; confronting, threat, chase, fight and alert. Territorial birds in the area hold one or more feeding sites out of their territories . Observation-area curves of territorial birds were classified into three patterns; sigmoid curve, cubic curve and straight line. Those occurrence frequencies changed seasonally and annually . And the size of feeding sites also changed seasonally and annually. Those changes were seemingly unrelated to the rates of territory fixing and to the sizes of territories. However , in every case, the activities of the birds clearly concentrated in feeding sites. Average territory size was 3364m2 in the first winter and 4519m2 in the next winter. The occurrences of roosting flights concentrated 30 minutes before and after sunset. Most of the birds flew north. In winter, white wagtail was seemingly dominant in Motacilidae, at least in the study area. Attacks against the predators were also observed.

Acknowledgements

We wish to express our gratitude to those members of Birds Study Group of Tama River in Tokyo University of Agriculture and Technology, who assisted us in our researches; Mr . T. AKASAKA, Mr. N. KATAI, Mr. K. TOKITA, Mr. M. MIYAKI, Mr. M. KOGANEZAWA, Mr. M. OTA, Mr. R. OKABAYASHI, Mr. N. NANBA, Mr. T. AKAMA, Miss A. MIKAMI, Mr. M. SHINKAWA, Miss M. KOBAYASHI and MISS A. IKEDA. Many suggestions and assistances on our researches by Mr. Shingo MIURA , Laboratory of Biology, Hyogo College of Medicine, and Mr. Yukitoshi TOTAKE, Itsukaichi Branch, Agricultural Experiment Station of Tokyo Metropolis are very much appreciated. We also thank to Dr. Isao MOTOTANI, Associate Professer of Faculty of General Education, Tokyo University of Agriculture and Technology, and Dr. Manabu ABE, Forestry Experiment Station, Tokyo for useful advises and assistances on our researches. We are grateful to Dr. Tsukasa NAKAMURA, Professor of Faculty of Education , Yamanashi University and Dr. Hiroki MIZUHARA, Associate Professor of Faculty of Agriculture, Tokyo University of Agriculture and Technology for useful comments on the munuscript .

(38) 昭和52年(1977)3月 Wintering ecology of White Wagtail 39

Literature Cited

DICE, L. R. and P. J. CLARK(1953) The statistical concept of home range as applied to the re- capture radius of the deermouse (Peromyscus). Cont. Lab. Biol. Univ. Mich. 62: 1-15. (by ODUM & KUENZLER,1955) Drost, R. und E. Schuz (1940) Ueber den Zug der europaischen Bachstelzen (Motacilla a. alba L. und M. a. yarellii Gould). Der Vogelzug 11 (4): 145-161. GOODWIN,D. (1950) Behaviour, Display and Feeding-habits of White Wagtail in winter-quarters. British Birds 43: 372. GREAVES,R. H. (1941) Behaviour of White Wagtail wintering in Cairo District. Ibis 14 (5): 459- 462. HANEDA, K. and T. ICHIKAWA(1967) Life history of the Eastern Gray Wagtail (Motacilla cinerea caspica). I. breeding season (1) nestbuilding, copulation, egg laying, incubation, chick raising. Jap. J. Ecol. 17 (3): 93-100. (in Japanese) HANEDA, K. and T. SHINODA(1969) A study of breeding biology of the Japanese Wagtail. Misc. Rep. Yam. Inst. 5 (6): 602-622. (in Japanese) HARTLEY,P. H. T. (1946) The song of the White Wagtail in wintering quarters. British Birds 39: 44-47. HVASS, H. (1963) Birds of the World. Methuen, London. JAPAN AVIAN SOCIETY (1974) Reports of basal researches on natural environment conservation. IV-A. Results of birds researches in Tama River. Department of Natural Environment Conservation, Bureau of Environmental Pollution, Tokyo Metropolis. (in Japanese) MARUYAMA,N., M. WATANABE,A. MIKAMI and Birds Research Group of Tama River (1974) On the winter ecology of white wagtail in the middle stream of Tama River. Proceeding of 21th annual meeting of The Ecological Society of Japan, 21: 147. (in Japanese) NAKAMURA,T. (1969) Structure of flock range in the Long-tailed Tit. 1. Winter flock, its home range and territory. Misc. Rep. Yam. Inst. 5(5): 433-461. (in Japanese) NAKAMURA,T. (1972) Structure of flock range in the Long-tailed Tit. 2. Home range and ter- ritorialism in breeding season. Misc. Rep. Yam. Inst. 6 (5 & 6): 424-488. (in Japanese) NOBLE, G. K. (1939) The Role of Dominance in the Social Life of Birds. Auk 56: 263-273. NICE, M. M. (1941) The Role of Territory in Bird Life. The American Midland Naturalist 3: 441-487. ODUM, E. P. and E. J. KUENZLER(1955) Measurement of Territory and Home Range Size in Birds. Auk 72: 128-137. RENDAHL,H. (1967) Die Zugverhaltnisse der schwedischen Bachstelzen (Motacilla a. alba). Ark. Zool. 19: 543-583. The Ornithological Society of Japan (1974) Check-list of Japanese Birds. Gakken Co. Ltd., Tokyo. TINBERGEN,N. (1965) Social Behaviour in Animals. Methuen & Co. Ltd., London. WHITE, C. A. (1950) Behaviour, Display and Feeding-habits of White Wagtail in winter quarters. British Birds 43: 373. WON, Tyong-Oh, Han-Chung WOO, Kyu-Whang HAM and Moo-Doo YOON (1966) Seasonal distribution and ecology of migrant bird populations by mist-netting and banding in Korea (I). Misc. Rep. Yam. Inst. 4 (6): 405-444. (in Japanese) YOSHII, M. and Y. HASUO (1969) Seventh annual report on the bird-ringing for the year ending 31st March 1968. Misc. Rep. Yam. Inst. 5 (5): 511-533. (in Japanese) YOSHII, M., Y. HASUO and N. ICHIDA (1970) Eighth annual report on the bird ringing for the year ending 31st March 1969. Misc. Rep. Yam. Inst. 6 (1 &2): 32-53. (in Japanese) ZAHAVI, A. (1971a) The function of pre-roost gathering and communal roosts. Ibis 113: 106-109. ZAHAVI, A. (1971b) The social behaviour of the White Wagtail Motacilla alba alba wintering in Israel. Ibis 113: 203-211.

(39) 40 山階鳥研報第9巻第1号(No.48)

多摩川中流域におけるハクセキレイの越冬生態について

渡辺通人*・丸山直樹**

ハクセキレイの生活様式を明らかにするため,多摩川中流域において亜種の一つであるMotacilla alba lugensの越冬生態の調査を行なった。調査は,中央線多摩川鉄橋上流の約6haの地域ならびに残堀川の

一部で ,1972年11月から1974年3月にかけて7回にわたって行なった。

1.ナワバリおよび防衛されない採食地は11月までには完成し,それは渡去直前まで維持されるものと考えられた。

2.ナワバリは1羽または2羽で占有され,この2羽の組み合せは,羽ふるわせ誇示・垂直飛び誇示の関係から雄と雌であるように考えられた。そして,これらのナワバリの間を放浪しているナワバリ非占有

個体がいることが確かめられた。 3.ナワバリ防衛行動には,confronting, threat, chase, fight, alertの5っのパターンが認められた。

この地域のナワバリ占有個体は,ナワバリ以外に防衛されない1つまたはそれ以上の採食地を持っている

ことが考えられた。

4.ナワバリ占有固体の示したobservation-area curveには,ロジスティク曲線型,三次曲線型,直線型の3型が認められ,これらの型を示す個体数には季節変動・年変動がみられた。

5.また,feeding siteの面積にも季節変動・年変動が認められたが,これらの変動とナワバリ定着率あるいはナワバリ面積とは直接の関係があるとは考えられなかった。しかしながら,いずれの場合もハクセキレイの活動はfeeding siteに集中していた。

6.ナワバリ面積の平均値は,1972-1973年冬の場合3364m2であり,1973-1974年冬の場合4519m2 であった。

7.就塒行動は,日没前後30分の時間帯に集中して観察され,北方へ去る個体が多かった。

8.ハクセキレイは,この地域においては冬の間セキレイ科内で最も優勢な種であると考えられた。また,ハクセキレイのpredatorと考えられる鳥に対する攻撃行動も観察された。

*富士学苑高等学校:山梨県富士吉田市下吉田870 **東京農工大学農学部:東京都府中市幸町3-5-8

(40) 昭和52年(1977)3月 Wintering ecology of White Wagtail 41

Appendix 1. Observation-area curves of white wagtail.

Appendix 2. Observation-area curves of white wagtail.

(41) 42 山階鳥研報第9巻第1号(No.48)

Appendix 3. Observation-area curves of white wagtail .

Appendix 4. Observation-area curves of white wagtail .

(42) 昭和52年(1977)3月 Wintering ecology of White Wagtail 43

Appendix 5. Distribution of activity densities on December 28, 1973. Enclosed area with thick line represents the feeding site.

(43)