摘要:

Red panda behaviour was studied in the Wolong Reserve, Sichuan, China to understand better the ecology of this herbivorous member of the Carnivora. Leaves of montane bamboo were the most common food in all months (93.7% of 791 droppings), supplemented in spring with bamboo shoots, and in late summer with arboreal fruits. Home‐range estimates by radiotelemetry for one adult female (94 ha) and one adult male (111 ha) most closely approximated allometrically‐predicted range size for omnivores. Pandas were active45–49% of the time, with highest levels in April, and, for the female in summer when lactating. Activity was higher in daylight than at night, especially in summer, coincident with arboreal foraging. The hypothesis that pandas rest in direct sunlight in winter to minimize heat loss while reducing peripheral circulation, was inferentially supported by their spending significantly more time resting on clear compared to overcast winter days. The red panda's anatomy, diet and low metabolic rate suggest an arboreal folivorous lineage incorporating terrestrial foraging to capitalize on a super‐abundant food resource–bamboo. Energy content of the annual recruitment of bamboo leaves within home ranges was substantially greater than annual energy requirements predicted allometrically. Gross food availability was not limiting to the radio‐collared pandas, but may have been so in unoccupied habitats with a lower bamboo density following the bamboo die‐back. Maternity den trees are probably a limiting resource in clearcut and deciduous fo

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1991.tb03821.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

Paracerceis sculpta (Holmes) is a sexually dimorphic sphaeromatid isopod crustacean inhabiting intertidal zones in the northern Gulf of California. Adult females in this species undergo a biphasic moult that initiates their sexual receptivity. Coincident with this moult, females experience anatomical changes associated with oviposition and gestation of young within the female marsupium. These modifications restrict female mobility, prevent females from feeding, and ultimately result in obligate female semelparity. In this paper, I describe the external and internal anatomy of premoult, half‐moulted and postmoult females collected from breeding aggregations in intertidal sponges. Field‐collected premoult females possessed hard, lustrous cuticles, and did not contain sperm. Females in half‐moulted condition contained sperm masses in both oviducts. Postmoult females contained developing embryos in internal brood pouches, and possessed cuticles that were pliable, translucent and setose. Embryos completed their development within postmoult females and dispersed from their mothers as mancae. Gestation duration decreased with increasing ambient temperature, from a maximum of 75 days at 12 dGC to a minimum of 13 days at 35 dGC. Female fecundity correlated positively with female body length. Spent females, depleted of lipid stores and muscle mass, died within two weeks of releasing mancae. ‘Female metamorphosis’ is considered a taxonomic character in certain sphaeromatid species descriptions. Anatomical changes in reproductive females similar to those inP. sculptamay occur in these specie

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1991.tb03822.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

Both juvenile and adultHelix asperaandH. lucorumshowed significant periodicities in locomotor activity close to an imposed 24‐h die1 of 13L: 11D, and to 20 diels of 13L:7D and 11L: 9D.Helix aspersais active earlier in the night in 24‐h diels thanH. lucorum. In both 20‐h diels H.aspersashowed a lag in attaining peak activity. We discuss the fact thatH. aspersacopes better with 13L:7D andH. lucorumcopes better with 11L:9D. Although both of them seem to grow faster in the 24‐h diel,H. lucorumis indifferent to photoperiod in relation to its growth. Helix aspersa became mature in four months in all the three regimes, but its size and maturity were influenced by the three photoperiod regimes. Egg‐laying was also influenced by the photoperiod regimes, but hatchin

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1991.tb03823.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

The batMyotis adversushunts for prey by aerial hawking and by taking prey from the water surface with its feet (trawling). The flight performance and echolocation of this species were studied in Queensland, Australia, and comparisons were made withMyotis daubentoni, a bat filling a similar ecological niche in the Palaearctic Region. The bats foraged in very similar ways, using the same foraging tactics and feeding in similar habitats, yet they were not geometrically similar in shape. The slightly largerMyotis adversushad relatively larger wings thanM. daubentoni, conferring a slightly lower wing‐loading. Nevertheless,M. adversusflew faster thanM. daubentoniduring the searching phase of foraging.Myotis daubentoniturned in tighter circles thanM. adversus. Both species used short frequency‐modulated (FM) echolocation calls of a characteristicsigmoidalstructure, and nulls typically observed in the calls were an observational artefact.Myotis adversusalso adopted an unusual ‘long’FM call while foraging. The relations between echolocation frequencies and body size were explored in maleM. adversus. Specialized morphological and acoustic adaptations for prey capture by trawling in insectivorous bats are di

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1991.tb03824.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

Antisera to serum albumins from five West Indian species of the frog genusEleutheroductyluswere prepared, and the reciprocal immunological distances (IDs) obtained were used to provide a time frame for the evolution of this group in the West Indies. One‐way IDS were obtained to 25 additional species within the genus, with emphasis on those from the West Indies. These immunological data support both a recent classification ofEleutheroductylusbased on an analysis of slow‐evolving allozyme loci, and the monophyly of the 17 native Jamaican species as indicated by a more comprehensive electrophoretic study. This is in contrast to the results of morphological studies supporting multiple invasions of Jamaica byEleutherodactylus. Within the subgenusEuhyas, IDS ranged from6–27 between Jamaican species, whereas between species on different islands the range was29–67. The subgenusSyrrhophusin southern North America was found to be the sister group to the subgenusEuhyus, a western Caribbean clade.Pelorius, a subgenus restricted to Hispaniola, was found to be the sister group of the subgenusEleutheroductylusin the West Indies. The largest IDs obtained for West Indian species were those between the two major groups, the subgeneraEleutheroductylusandEuhyas.The albumin immunological clock forEleutheroductyluswas calibrated with three events in the geologic history of the Caribbean: the breakup of the proto‐Antilles (65‐75 million years before present [mybp]), the emergence of Jamaica (20‐30 mybp), and the uplift of the Blue Mountains in Jamaica (5‐10 mybp). Immunological distances corresponding to those events yield a calibration of 1 ID=0.60 million years (my), the same as that previously obtained for other groups of amphibians and thus supports the use of albumin immunological distance as a molecular chronometer in the genusE

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1991.tb03825.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

The Manx shearwater colony in the mountains of Rhum receives a high average rainfall, around 3000 mm, and nest burrows are subject to flooding. Colony hatching success rates on Rhum and neighbouring Canna are significantly negatively correlated with rainfall amounts during the incubation period. The incidence of heavy rainfall during incubation has a greater influence on hatching success than does total rainfall. Fledging success is unrelated to rainfall. Burrows vary with respect to their susceptibility to flooding during heavy rain. A ‘Flooding Likelihood Index’(FLI) was devised which allowed 100 study burrows to be ranked with respect to their risk of flooding in a given rainfall event. Eggs were significantly more likely to be laid and to hatch in burrows less susceptible to flooding. In 1984 and 1985 the overall breeding success rate in burrows with an FLI lower than the median was more than twice that in those with higher than median FLIs. Male shearwaters showed a significantly greater tendency to move to different burrows following breeding failure in the previous season. This may be an adaptive response to the consistent differences in the quality of individual burrows. The shearwater population on Rhum may be limited by the availability of good quality nesting burr

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1991.tb03826.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

The South American sun‐star,Heliaster helianthus, is capable of adopting both the extraoral and intraoral mode of feeding. Observations were made on the feeding activities ofH. helianthusin an intertidal habitat in central Peru. The proportion of individuals engaged in intraoral feeding was high amongst smallH. heliunthusof less than 14 cm in diameter and gradually declined in larger size classes. Extraoral feeders had significantly larger meal sizes (total prey biomass) than intraoral feeders in all the size categories ofH. heliunthus. Extraoral feeders also consumed larger individuals of the most important prey species,Semimytilus algosus, than intraoral feeders. The advantages and disadvantages of the two feeding modes are discussed and the meaning of the dual foraging tactics inH. helianthusis considere

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1991.tb03827.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

The colonizing ability, catholic habitat utilization and wide distribution of house mice (Mus domesticus, Rutty) are indicators of their ecological resilience. Numerous studies have been made of commensal, caged and free‐living mouse populations though few have assessed the relative importance of physiological and genetical components of adaptability in a simple ecosystem. This paper reports such findings, derived from live‐trapping which formed part of an inter‐disciplinary study of adaptability in a feral population of house mice living on a small Scottish island (57 ha).The population size ranged from450–3250 animals. A high proportion of mice showed homerange tenacity, though15–20% shifted their range during winter. This ‘churning’ of the population is consistent with the island population forming an effectively panmictic unit rather than fragmented demes. The breeding season, survival of individuals and change in population size related to patterns of gross climatic variation (temperature and rainfall) so that rates of reproduction and survival were lowest in cold, wet conditions. Thermoregulatory adjustment of the mice to lowered ambient temperatures and its contribution to overwinter survival are discussed. Genetical monomorphism of May Island mice is discussed in relation to their biological performance compared with other populations, especially that of the ecologically comparable Skokholm I

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1991.tb03828.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

Two nematomorph species are recorded from New England and described:Parachordodes lineatus, a little‐known North American species, andP. violaceus, a European species not previously verified for North America. The identity and species status ofP. lineatusis firmly established and the presence ofP. violaceusin North America is confirmed. Description is based both on light microscopy, which is found to be sufficient to distinguish the two species ofParachordodes, and scanning electron microscopy, which is necessary to elucidate details of cuticle structure and male posterior morphology. The status of the genusGordionusin North America and the practice of splitting genera within the Gordioida are discusse

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1991.tb03829.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

Echidnas (Tachyglossus aculeatus) in wheatbelt reserves in Western Australia are primarily termite‐ and ant‐eaters. Using captive and free‐ranging animals, we tested whether echidnas respond to high density patches of these prey and also to differences in their mechanisms of defence. When feeding on termites, free‐ranging echidnas generally adjusted their foraging effort in response to prey abundance, increasing their rate of energy intake by digging deeper and allocating more time to patches where prey were abundant. Such efficient foraging occurred irrespective of whether termite defence was mandibulate, chemical, or a combination of both, as inAmitermes neogermanus. Echidnas invested little effort in species ofDrepanotermesin the field despite their abundance at local food patches, probably because the soldiers are large and aggressive and produce copious quantities of pungent defence secretions. Echidnas also avoidedNasutitermes exitiosusin the field but ingested other species with chemical defence such asTumulitermes. Captive echidnas decreased their foraging effort onN. exitiosusonly when soldiers were abundant (400 per unit area) and the soldier to worker ratio was high (80:20), hence avoidance of this species by free‐ranging echidnas may reflect the species'ability to mobilize quickly large numbers of soldiers to colony breaches. When feeding on ants in the field, foraging effort and prey energy in food patches were not correlated, possibly because ants responded rapidly to colony breaches by emerging to meet the predator. More extensive soil excavations by foraging echidnas to capture ants were thus unnecessary, minimizing foraging effort. Captive and free‐ranging echidnas rejected ants 7 mm (except in the presence of energy‐rich eggs), and>10 mm long, respectively, reducing foraging efficiency to zero when encountering such prey. With such exceptions, the results suggest that echidnas make efficient use of patchily distributed prey and generally adjust their foraging efforts to match actual ener

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1991.tb03830.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY