摘要:

There are two resident seals in the Outer Hebrides: the grey sealHalichoerus grypuson the exposed coasts, and the common sealPhoca vitulinaon the sheltered ones. This paper describes the first exhaustive survey of the breeding status of the grey seal in the archipelago, conducted from land, sea and air in the autumn of 1961. Expeditions visited Shillay and North Rona, and aerial photographs were obtained of all the other islands except Stockay, Flodday and St. Kilda, for which information was obtained from other reliable sources.The data obtained concerned the number of pups present at one day in the breeding season. The birth‐rate curves for Shillay (1955) and North Rona (1959) were used with these data to give indices of the number of pups produced by each colony in 1961. Separate assessments were made for Stockay, Flodday and St. Kilda. Possible sources of error are discussed.The following are the indices for number of pups in 1961: North Rona, 2,600; Gasker, 1,094; Shillay, 150; Haskeir, 113; St. Kilda, 100; Causamul, 84; Coppay, 80; Stockay, 50; Kearstay, 20; Deasker, 17; Flodday, 50. For the Outer Hebrides as a whole the index is 4,378 or approx. 4,400.The history of the grey seal in the Outer Hebrides is reviewed. An increase in stocks is evident throughout the last century subsequent to the evacuation of North Rona in 1844. This is attributed to the gradual human depopulation of the area, with remote islands such as North Rona, St. Kilda and the Monachs becoming deserted by man and subsequently colonized by seals. The increase began well before 1914 when the Grey Seals Protection Act was passed, but this has since preserved stock

ISSN:0370-2774    

DOI:10.1111/j.1469-7998.1963.tb01620.x

出版商:Blackwell Publishing Ltd    

年代:1963

数据来源: WILEY

摘要:

Re‐examination of the gut of the earthworm,Lumbricus terrestrisL. reveals that the oesophagus is divisible into three parts of which the wall of the anterior part is thrown into broad longitudinal folds, the second part strongly ciliated and the third part folded longitudinally. The relationship between the ciliated section and the secretion of microerystalline calcium carbonate is discussed.The folds of the crop, hitherto neglected from a functional standpoint, (a) play an integral part in regulating the rate at which the ingested material is passed on to the gizzard, (b) prevent regurgitation and (c) possibly assist the mixing of food with calcium carbonate, thus affecting flocculation of the ingested soil.The intestine is folded and divisible into four regions. The short first part bears sac‐like extensions which are continually dilating and contracting. These extensions are lacking from the second part, but in common with the first part have the typhlosolar intucking divided by a large number of transverse folds, which are separated from one another by grooves. Each “fold” consists of plications of the “lateral epithelium” of the typhlosole and the incorporation of the plicated epithelium of the dorso‐lateral wall of the tract. These epithelia are partly composed of glands that secrete an acid mucopolysaccharide, which forms the peritrophic membrane. The typhlosole in the third part of the intestine is a continuous, smooth intucking of the dorsal wall and lacks divisions into transverse folds, but it ceases at about two‐thirds the length of the intestine. In other respects it is similar to the second part. The fourth and terminal section of the intestine has no typhlosole, and in contrast to the anterior three parts lacks

ISSN:0370-2774    

DOI:10.1111/j.1469-7998.1963.tb01621.x

出版商:Blackwell Publishing Ltd    

年代:1963

数据来源: WILEY

摘要:

A collection of skins of the brown hare, obtained in Banffshire, Scotland, was examined in order to determine the number and duration of the annual moults, and to compare these with the moults of the mountain hareLepus timidus scoticus.It was found that the adult brown hare moults twice annually, and that moulting in brown and mountain hares may vary with age and sex. The influence of day length, temperature, and endocrine glands is considered.

ISSN:0370-2774    

DOI:10.1111/j.1469-7998.1963.tb01622.x

出版商:Blackwell Publishing Ltd    

年代:1963

数据来源: WILEY

摘要:

Sixty species of Australian ascidians were identified in material from the British Museum (Natural History). One new genus,Pseudodiazonais described and five new species,Aplidium broomeiensis, Synoicum bowerbanki, Euherdmania digitata, Pseudodiazona sabulosa, andStolonica carnosa.

ISSN:0370-2774    

DOI:10.1111/j.1469-7998.1963.tb01623.x

出版商:Blackwell Publishing Ltd    

年代:1963

数据来源: WILEY

摘要:

Analysis of the food items stored in the crops of nestling wood‐pigeons, which were collected during the period July to October 1957, showed that their diet consisted mainly of cereal grains, with legume or mustard seeds of local importance. Weed seeds and leaves and some animal material comprised only a small proportion of the food. Nestlings collected in May in Cambridgeshire had been fed primarily on weed seeds suoh asCerastiumandRanunculusspecies but increasing proportions of cereal grains were noted towards July. In early July unripe grain was collected. The mean daily weight of nestlings hatched in late June was below that of others examined in August and September. Similarly feather growth was retarded and many of these early nestlings died in the nest, apparently due to malnutrition. For the first three days of life the squabs were fed on crop milk but after this time environmental foods became increasingly important. Broods of one grew more quickly than broods of two and the absence of any clutch size adaptation to the food supply is discussed. In a study area near Newmarket the breeding season coincided with a peak in the availability of grain. The factors controlling this timing are discussed and food is considered to be the most important “ultimate” and “proximate” factor (Baker, 1938) concerned. A low nestling survival was recorded for those broods reared outside the period when optimum feeding conditions existed. Thus natural selection could eliminate early or late breeders. The condition of the gonads suggested that the pigeons were capable of breeding long before they did so. Egg laying was only partly synchronous throughout the population and occurred when the food supply was improving. It is considered that the food supply, by affecting the timing and duration of intra‐pair courtship and hence ovulation, could have been the main proximate factor regulating the onset of

ISSN:0370-2774    

DOI:10.1111/j.1469-7998.1963.tb01624.x

出版商:Blackwell Publishing Ltd    

年代:1963

数据来源: WILEY

摘要:

The ability of the Rottnest Island population of the quokka (Setonix brachyurus) to replace lost pouch young from stored blastocysts has been examined. It was found that, under experimental conditions, young were replaced throughout the breeding season. However, the age distribution of the young in the wild population provided evidence that there was no considerable replacement from stored blastocysts in the field. The maximum replacement under experimental conditions was 60 per cent at the beginning of the breeding season in February. The percentage of animals producing further young declined gradually after this until in August, when seasonal anoestrus commences, no young removed from the pouch were replaced from stored blastocysts. Factors which may affect the ability of the animals to produce young from stored blastocysts, and the decline in success throughout the breeding season are discussed.

ISSN:0370-2774    

DOI:10.1111/j.1469-7998.1963.tb01625.x

出版商:Blackwell Publishing Ltd    

年代:1963

数据来源: WILEY

摘要:

The development of the egg ofPolymorphus minutus, an acanthocephalan parasite of water birds, is described. It is compared with the published descriptions of the embryology of the only other two species of the phylum which have so far been studied. The three species represent each of the three groups of the phylum, and this allows an overall assessment of the peculiarities of embryonic development in the phylum to be made. It is shown that it is very unusual, the polarity of the egg being reversed, the first two cleavages being more or less parallel, the cellular boundaries disappearing at an early stage and most of the nuclei condensing and forming a compact central mass.

ISSN:0370-2774    

DOI:10.1111/j.1469-7998.1963.tb01626.x

出版商:Blackwell Publishing Ltd    

年代:1963

数据来源: WILEY

摘要:

The early development of the hyoid ofNeoceratodusis described, and its structure and topography are compared with relevant components in various urodele larvae. These include;Hynobius nebulosus, Hynobius (Salamandrella) keyserlingii, Hynobiua retardatua, Cryptobranchus japonicus, Cryptobranchus alleghaniensis, Salamandra maculosa, Ambystoma mexicanum. Necturus maculatus, Desmognathus fuscus fuscus, Desmognathus quadrimaculatus, and Plelhodon cinereua.It is concluded that inNeoceratodusthe stylohyale develops from the quadrate cartilage, and the otoquadrate cartilage derives from a pharyngohyale, which is recognized in urodeles as a post‐palatine cartilage. The columella (and stilus) of the latter co‐exists with a pharyngohyale, and thus may either derive from the hyoid blastemasui generic, or alternatively from an epihyale‐laterohyale component of an ancestral stock common to Dipnoi and Ur

ISSN:0370-2774    

DOI:10.1111/j.1469-7998.1963.tb01627.x

出版商:Blackwell Publishing Ltd    

年代:1963

数据来源: WILEY

摘要:

An account is given of an intersexual fin whale where testes associated with a uterus, and a grossly deformed clitoris, are among a number of interesting features described, Whether it is a hermaphrodite or pseudo‐hermaphrodite, and the rarity of similar records in the Cetacea, are briefly discusse

ISSN:0370-2774    

DOI:10.1111/j.1469-7998.1963.tb01628.x

出版商:Blackwell Publishing Ltd    

年代:1963

数据来源: WILEY

摘要:

The seasonal colour changes of mountain hares (Lepus timidus) were studied by standardized field observations in Scotland. The rate of colour change in spring varied according to the climate, being retarded in very cold springs and hastened in mild springs. Hares at high altitudes turned white earlier and more completely than hares at low altitudes, and turned dark later in spring. The colour and moult of different individuals varied greatly. Late‐born young turned white later in autumn than fully grown hares. Climate and light cycle are discussed in relation to these colour change

ISSN:0370-2774    

DOI:10.1111/j.1469-7998.1963.tb01629.x

出版商:Blackwell Publishing Ltd    

年代:1963

数据来源: WILEY