HANBDA, Kenzo and Yohko TAKAHASHI (Shinshu Univ., Nagano) Life history of the Japanese Red-tailed Shrike (Lanius cristatus superciliosus) I. Breeding season. Jap. J. Ecol. 18,47-56 (1968). This report deals with the arrival, nest building, courtship and copulation, egg-laying, incubation, feeding, family-stage, distribution of pairs and territories, and the share of the work done by the male and female in breeding of the Japanese Red-tailed Shrike, and is based on the results of field observations from May, 1965 to September, 1966 in the Zenkoji basin (altitude about 400m), Nagano Prefecture. The main part of the observations was done on the ground of the Zenkoji Temple in the center part of the basin. The life history during the breeding season of the bird is based on the observation of one nest in 1966.
KAWAKATSU, Masaharu (Biol, Lab., Fuji women's Coll., Sapporo), YAMADA, Tatsuya (Nayoro City Girls' High School, Nayoro), IWAKI, Sumie (Biol. Lab., Fuji Women's Coll., Sapporo) and TOKUI, Toshinobu (Hokkaido Salmon Hatchery, Sapporo) Report on the ecological survey of freshwater planarians in the Yurappu River system, Hokkaido. Jap. J. Ecol. 18,56-60 (1968). The vertical distribution of freshwater planarians in the Yurappu River system in South Hokkaido (Lat. 42°10′N. to 42°23′N. and Long. 140°00′E. to 140°18′E.) is reported. The Yurappu River system (Yurappu, Sarambe, Otona, Namarikawa, Penkerupeshupe, Towarubetsu and the Seiyobetsu Rivers) is one of the typical rivers in South Hokkaido ; it drains into Funka (Uchiura) Bay, the Pacific Ocean. The area of the Yurappu River system is the lower mountainous land (the highest peak, Mt. Yurappu, is 1275 metres above sea level). Surveys of the majority of the stations were made in August, 1967. In the area surveyed, three species of freshwater planarians, Dugesia japonica ICHIKAWA et KAWAKATSU, Polycelis sapporo (IJIMA et KABURAKI) and Polycelis auriculata IJNDA et KABURAKI, were found. D. japonica was found at the stations in the plain (below the altitude of 10 metres). Pol. sapporo was common at the stations both in the plain and the mountainous district (below the altitude of about 350 metres). Pol. auriculata was rather common at the stations ranging from about 80 to 410 metres in altitude. The inhabitable water temperature ranges of these three species are : D. japonica (18.6〜24.3℃) ; Pol. sapporo (8.6〜20.2℃) ; Pol. auriculata (8.6〜18.9℃). The type of the vertical distribution in the area surveyed is shown as JSA-SA-A (J : D. japonica ; S : Pol. sapporo ; A : Pol. auriculata).
TEZUKA Yasuhiko (Laboratory of the Science of Living, Faculty of Science, Tokyo Metropolitan University). A method for estimating bacterial respiration in natural water. Jap. J. Ecol. 18,60-65 (1968). A new method is described whereby the bacterial respiration in natural water taken from the eutrophic lake can be estimated. The bacterial population is separated to some extent from other planktonic organisms by size fractionation using a Millipore filter of 8 or 5 μ porosity. Based on the respiratory activity of the bacterial population thus obtained and the change in the size of the bacterial population in the natural water, the bacterial respiration in the natural water can be calculated. By comparing the respiration of the bacterial population with that of the total planktonic organisms including the bacteria, the role of the bacterial population in the mineralization process can be estimated. The results of some experiments showed that the percentage of bacterial respiration to total plankton respiration varied widely from sample to sample in the range of 6 to 55. Problems associated with this method were also checked or discussed.
ONO, Yoshiaki and Tatsumi UEMATSU (Kagawa Univ., Takamatsu) Experimental analysis of the sign stimuli in the mating behaviour in Oryzias latipes. Jap. J. Ecol. 18,65-74 (1968). Sign stimuli releasing the mating behaviour of the male fish in Oryzias latipes were analyzed through the models. In Experiment I the movement pattern of the stimulating source was analyzed through Model A (dead fish) and B5 (ichthyoid shaped). In Experiment II the body form was analyzed with 10 kinds of models (Mode A-J). The models fastened to the ends of the silkworm guts hung down from the T-shaped model-manipulator were set in motion through the manipulator by hand in both experiments (Experiment I and II). The direction and velocity of movement and the size of the models were analyzed in Experiment III and IV respectively through the models set in motion mechanically by the motor. The following results were obtained in these experiments. Experiment I. 1) When the model was set freely in motion like the normal swimming and sometimes was made to show head-up (M2), the mating behaviour of the male was most remarkably released. 2) But also in the horizontal movement of the model the mating behaviour of the male was fairly observed. 3) Even only the head-up of the model released a little mating behaviour. 4) The beating (F8) was often observed in the horizontal movement of the mode. 5) The results obtained with Model A showed little better values than those with Model B5. Experiment II. 1) Arranging the models in descending order of their effectiveness, the following formula is obtained. A (dead fish)>B5 (ichthyoid)>E (inversed isosceles triangular board)>D (cylindrical)>H (semi-circular board)>G (fishlike triangular board)>C (conic)>F (isoscles triangular board)>I (spherical), J (fishlike tin-plate sheet). 2) Model A showed the bert results among all. 3) Model C showed the mating behaviour only in two instances and Model F also only in one instance. 4) No reaction to Model J was observed. 5) Not a few individuals showed crouching (F5) to Model I. From these results it is concluded that the elongated solid of a certain size can release the mating behaviour. Furthermore, the swollen ventral part of the female is regarded to be effective to release the mating behaviour in the male. Experiment III. 1) The beating (F8) are more often observed in the horizontal movement than in the up-and-down one. Also the mating behaviour was more frequently observed in the former than in the latter when both movements were of equal velocity. In general, however, the direction of the movement is not so important to influence the mating behaviour. 2) Both the frequency of the mating behaviour and the number of the reacting individuals are rather high within the velocity of 78.2-163.2cm per minute. This velocity coincides with the normal swimming velocity in the fish. Experiment IV. 1) The mating behaviour has the highest releasing valency when the size of the model is 24.0-30.0mm. 2) The ratio of body length of 1.00-1.20 showed the best results. 3) The larger than B7 (28mm) the body length of the model is, the fewer the frequency of the mating behaviour becomes. The smaller than B5 (24mm) the former is, the fewer the latter becoms. 4) The crossing (M6) was observed only within the size of the model 20.0-28.0mm. The effective of the sign stimuli in the mating behaviour with special reference to the ratio of body length and the body form is narrower than in the schooling behaviour. This is regarded to have probably a profound relation with the fact that while the schooling behaviour is general or fundamental through the individual life, the mating behaviour is comparatively special or limited only in the adult.
Hosomi, Akimichi (Kobe Ikuei High School) The ecological study on the adhering, growth and death in population of Mytilus edulis L. at the seashore of Suma in Kobe. Jap. J. Ecol. 18,74-79 (1968). Observation were made on Mytilus edulis that adhered to the jetty for sand arrestation at the seashore of Suma, from Feb. 1966 to July, 1967. When the concrete jetty was built at the inter-tidal zone in Feb. 1966,the population of less than one year old Mytilus edulis appeared in about July, 1966. The population spread on the vertical side of the jetty and then declined gradually, and disappeared comletely by Aug, 1967. The observations revealed the following facts : 1) The period when of maximum adherence is from Apr. to July. 2) Growth of the height of bivalves is 49mm in average, in a year from the time of larval shell adhering. The rate of growth declines to the minimum in Jan. 3) The average sizes of the dead bivalves shells in population are smaller than the living ones. The number of dead shells becomes most abundant in winter. 4) The populations have complex structure composed of double strata mainly in the winter when the population thrives well.
NAITO, Toshihiko, IWANAMI, Yuuki and Shigeru IIZUMI (Tohoku Univ.) Some effects of fire on the regeneration of Sasa palmata. Jap. J. Ecol. 18,79-82 (1968). The burnt Sasa-type grassland described in this paper is situated in the Kawatabi Farm, Miyagi Prefecture. Before the 1965 fire, there had been no grazing and firing in this grassland, therefore, dead culms and leaves on the soil surface were abundant. The present study was made to clarify the regenerative vigor of Sasa palmata after the fire on May 26,1965. In August, 19■, the height and diameter of culms and the leaf area of the resprouted Sasa plants were decreased in the burnt area compared with the unburnt area. But, in the second year after the fire, no difference between the burnt and unburnt areas in these characters of resprouted organs was noticed. Therefore, the productive structure of the Sasa palmata community was developed with two strata of leaves in relation to the height of the community and the longevity of culms at the burnt area. But the phenomena mentiond above were not seen in the third year. On the other hand, The mode of distribution of these resprouted plants was contagious during two years after the fire. In addition, the field burnings were carried out in the Sasa-type grassland at Suzuri-ishi, Miyagi Prefecture. The temperatures during the fires at various heights were measured by means of the thermocouples. The highest temperature recorded was about 700℃ at the height of 11 to 14cm above the soil surface. But, the burning temperatures below the soil surface did not exceed 65℃. Therefore, the underground organs of this species were not affected by fire.