Winter flocks of Silvereyes (Zosterops lateralis), consisting of different races, were studied at a feeding station in Armidale, N.S.W., in 1961 and in captivity in 1961 and 1962 to analyse social relations of the flock members. They showed the same agonistic displays as are known for the New Zealand race. Southern migratory birds tended to dominate local birds and males were likely to be more dominant than females, though neither of these tendencies was statistically significant at all times. Prior residence and social conditioning as modifiers of dominant-subordinate relations did not have lasting effects. The hierarchy derived from aggressive encounters was a linear type in the field and in cages. However, the order changed under experimental conditions. The hierarchy and pair relations of 10 captive birds were established initially in an aviary and each of four pairs selected was isolated in a small cage. Then the cages were connected to allow free movements and finally the birds were transferred back to the aviary. The behaviour of birds in group activity was in the winter phase throughout the experiment, but the induced site attachment in isolation produced territorial defence behaviour in some males for a short period when the cages were connected. However, territorial behaviour did not lead to a territorial arrangement in the cage spaces. This was considered to indicate the significance of social relations in establishing a breeding territory at the end of winter. The measures of dominance and aggressiveness are considered to represent different properties of behaviour ; the linearity of hierarchy reflects how rigid the dominance order is whereas the rate of reverse pecks within a hierarchy relates the degree of aggressiveness of individual birds to the dominance order. Aggressive encounters are the result of aggressive responses of one bird to different stimulus situations provided by another bird and further studies are needed for the understanding of motivation involved in agonistic behaviour.

View full abstract

As the factors for inducing the flight form in the population of the southern cow pea weevil, Callosobruchus maculatus, the influence of such parental conditions as old or young and early developed or late developed were examined. Percentage of emergence of the flight form was higher when the eggs from the late developed adult were used. The eggs deposited by rather older adults were apt to develop into the flight form. These results elucidate the findings mentioned in the previous papers (UTIDA, 1965 ; SANO, 1967) that (1) the flight form emerges at the later part of the emergence curve, and (2) the larvae at the younger stage is transformed into the flight form by the rise of temperature in the heap of beans caused by the metabolic activity of the fully grown larvae.

View full abstract

The vertical distribution of freshwater planarians in Kuroishi City, the Mt. Kushi-gamine district in the Towada National Park and in the Owani district (Lat. 40°20′N. to Lat. 40°40′N. and Long. 140°25′E. to Long. 141°00′E.), all in the central part of Aomori Prefecture, Honshu, was surveyed. Mt. Kushi-gamine (altitude, 1517m) is one of the main peaks of the Minami-Hakkoda mountains. The main river systems in the area surveyed are the Oirase, the Aseishi (a large tributary of the Iwaki River), the Hirakawa (a tributary of the Iwaki River) and the Shimouchi (the Yoneshiro River ; the upper course of the Noshiro River). Based upon the previous report (KAWAKATSU, TBSHIROGI & YAGIHASHI 1967), the distribution of freshwater planarians on the south-eastern slope of Mt. Iwaki was also surveyed. The surveys were made in 1966 and 1967. In the area surveyed, the following eight species of freshwater planarians were found : Dugesia japonica ICHIKAWA et KAWAKATSU, Phagocata vivida (IJIMA et KABURAKI), Phagocata teshirogii ICHIKAWA et KAWAKATSU, Phagocata sp., Polycelis auriculata IJIMA et KABURAKI, Bdellocephala brunnea IJIMA et KABURAKI, Bdellocephala sp. and Dendrocoelopsis lacteus ICHIKAWA et OXUGAWA. D. japonica was found to be common at many localities of the plains and the mountainous areas. This species was found at the stations below the altitude of about 480 metres (inhabitable water temperature range, 1.0〜25.0℃). In the area surveyed, Ph. vivida and Pol. auriculata were distributed widely. Ph. vivida found at the stations within the altitude range of about 40 to 920 metres (2.0〜20.0℃). Pol. auriculata was found at the stations within the altitude range of 120 to 1280 metres (4.5〜19.0℃). The type of the vertical distribution in the area surveyed is J-JV-JVA-VA-A (J : D. japonica ; V : Ph. vivida ; A : Pol. auriculata). Ph. teshirogii and Bd. brunnea were found in some springs and spring-fed streams in the plains. Phagocata sp. and Bdellocephala sp. were found at some localities in the Tsutanana-numa district in the Towada National Park. Den. lacteus had been found only in Hokkaido in North Japan. Large populations of this species were found in the vicinity of Kuroishi City (an orchard of apples at Rokumantai) and at some localities in the Mt. Iwaki district in Aomori Prefecture. In the Rokumantai district, Den. lacteus was found to be common in many springs, brooks and in shallow streams fed by the thawing of anow (altitude, 150〜340m). This is the first record of occurrence of this species in Honshu.

View full abstract

One of the most interesting problems in the natural history of the arthopod-borne viruses is their mechanism of survival during the interepidemic period. Mosquitoes overwintered and trapped in April and May by the dry ice-light trap had longer wings than the summer mosquitoes, while the mosquitoes caught in the fall had shorter wings than the overwintered mosquitoes, though an exceptional specimen of parous female was caught in the Mibayashi district (Fig. 1,Table 1). From the middle of September to October, the wing length of the blood-engorged females caught in the cow shed was as short as those of the mosquitoes collected by the dry ice-light trap. However, the wing length of the mosquitoes emerged from pupae caught in the paddy field, reservoir, and abandoned drain was longer than that of the blood-fed female. The wing length of these mosquitoes was about the same as that of the overwintered female (Fig. 1,2). Experimental data show that the specimens reared in low temperature and short photoperiod had longer wings than those grew in summer (Fig. 3,Table 2). These data indicate that the unfed, nulliparous female was predominant in the hibernating population, and this was probably induced to diapause by the autumnal, short photoperiod and low temperature.

View full abstract

Der Kasiyama-Schutzwald (Miyao-Staatsforst) liegt am Nordfuss im Sobo-Gebirge. Er erreicht die hohere Grenze der immergrunen Laubwalder. Die vertretende Pflanzengesellschaft, Skimmio-Cyclobalanopsietum acutae, ist in drei Teile untergeteilt : der erste ist das rhodo-dendretosum nudipedis auf den felsigen Graten, der zweite der typische Teil auf den Bergseiten und der dritte die Zelkowa-Fazies in der Talsohle. Aus den Belichtungsdiagrammen mit Kosinus vom Beschattungswinkel geschildert, wurde der orographisch bedingte dauernde Sonnenscheindauer graphisch gemessen. In der Talsohle, wo die Assoziation mit den sommergrlinen Waldern ersetzt ist, ist es gefunden, dass sich ein dauernde Sonnenscheindauer im Dezember bis an die Null vermindert. Durch den Vergleich aller Dominantarten jeder Schicht wurde es veranschaulicht, dass die Verbindung von Cyclobalanopsis acuta-Camellia japonica-Skimmia japonica od. Aucuba japonica-Ardisia japonica fur die Assoziation in diesem Bezirk typisch ist. Obgleich alle diese Art zur okologischen Gruppe vom immergrunen Laubwald gehort, dringen die sommergrunen Baume von den submontanen und dem Talwald okologischen Gruppen in die Baumschicht und einige Geophyten in die Bodenschicht von den heterogenen Bestanden an der Talsohle vor. Nur die schattenertragende Aucuba japonica-Strauchschicht bleibt dort als der letzte Vertreter der immergrunen Laubwalder.

View full abstract