摘要:

About 40Z of the pellets of the barn owl (Tyto alba),collected throughout the year in open and rural environments in Sicily, contained remains ofMicrotus savii.This percentage is an exception to the low proportions of Microtidae generally present in the barn owl's diet in the Mediterranean region. The biometrical study of 666 mandibles ofM.saviitaken from 1500 pellets allowed us to determine the monthly trend of the four different size classes, corresponding to age classes of this rodent. Adults and subadults were the most frequent prey; the peaks of juvenile and old adult voles were found respectively in May and September, which suggests an average life of 16 months for the voles.M.saviiwas the main component of the diet of the barn owl for eight months of the year, whereasApodemus sylvaticuswas the main component for only two months. This distribution of abundance of the few species preyed on by the barn owl agrees with the Motomura model. The regression of logarithm of occurrence of preys on abundance rank is more sloped ifM.saviiis at rank 1 than ifA. sylvaticusis at the same rank. We found a significant difference between the two slopes. It seems that in Sicily there is a local specialization of the barn owl to prey onM.savii.The daily food intake of this owl was estimated at about 80–85 grams, a value lower than that obtained in North‐Europe.

ISSN:0373-4137    

DOI:10.1080/11250008709355559

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

This study concerns the effects of three different ambient temperatures (10, 15 and 20–22°C) on the nest‐building activities of non‐reproductive female laboratory house mice; rats; Mongolian gerbils and golden hamsters. Nest‐building behaviour was assessed in terms of the quantity of shredded paper utilized and the type of construction (plate, bowl or covered) on a daily basis over 14 consecutive days. Mice and rats used more material and tended to build more complex nests at lower ambient temperatures. Female gerbils used more nesting material at the highest temperature and least at 15°C. However, female gerbils built the most elaborate structures at the lowest temperature. The use of more material at 20–22°C was not reflected in a better nest. Female hamsters used considerably more material at the two lower temperatures, and at the lowest temperature built nests that were superior in quality to those generated by controls (20–22°C). Measurement with a digital probe confirmed that temperatures within the nests were higher than in the immediate surroundings. Thus, although there are species variations in the nest‐building responses to different ambient temperatures (which may reflect the habitats of the species in the wild), it is clear that the nest enables rodent species to exploit a range of environments.

ISSN:0373-4137    

DOI:10.1080/11250008709355560

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

Götte's larvae ofStylochus mediterraneuswere examined at both the light and the scanning electron microscope. Specimens fed on the green algaDunaliellasp. showed green substances in their gut. Moreover, a ciliated protozoan of the genusAspidiscawas found half inserted in the mouth of a Götte's larva. These data are new evidence in favour of planctotrophic feeding in this type of larva.

ISSN:0373-4137    

DOI:10.1080/11250008709355561

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

Circadian rhythmicity in the average proliferation rate of the primary spermatogonial cell crop in the frog testis was studied by the stathmokinetic method. Colchicine was used to specifically block cells after they enter metaphase. Thein vivomitotic activity of primary spermatogonia was studied in three different periods of the year and was analyzed at 8 time points of the 24‐hour day. Circadian variations were suggested in all three periods of the year. Mitotic activity of the primary spermatogonia was also analyzedin vitroat 16 time points through a 48‐hour experimental period. Daily rhythmic fluctuations in the division rate of primary spermatogonia were observed. Thus, the proportion of cells in mitosis within the primary spermatogonial cell crop of the frog testis exhibits not only significant seasonal variations (as reported elsewhere), but also a daily rhythmic variation. The percent difference between low and high values of mitotic circadian rhythm varies with season.

ISSN:0373-4137    

DOI:10.1080/11250008709355562

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

ISSN:0373-4137    

DOI:10.1080/11250008709355563

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

ISSN:0373-4137    

DOI:10.1080/11250008709355564

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

ISSN:0373-4137    

DOI:10.1080/11250008709355548

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor