Abundant Food but Nowhere to Live

CSA News ◽  
2020 ◽  
Vol 65 (9) ◽  
pp. 8-11
Author(s):  
DJ McCauley
Keyword(s):  
1988 ◽  
Vol 66 (7) ◽  
pp. 1620-1625 ◽  
Author(s):  
Warren G. Holmes

The influence of white adipose tissue on sexual maturation was investigated in captive-born male Belding's ground squirrels (Spermophilus beldingi). Juveniles were given abundant food during the summer and by fall achieved prehibernation body masses approximating those of sexually mature males. Immediately before being placed in a cold room (5–8 °C, constant darkness) for a 7-month hibernation period, fat was surgically removed (lipectomy) or left intact (sham lipectomy). The following spring, paired testes mass, serum testosterone, and spermatogenesis were monitored, mating tests were conducted, and body fat levels were determined. All three physiological indicators of reproductive status were significantly higher in sham-lipectomized than in lipectomized males, only sham-lipectomized males inseminated females, and body fat levels were significantly higher in sham-lipectomized than in lipectomized males. Thus, sexual maturation was accelerated in male Belding's ground squirrels by providing juveniles abundant food so they achieved body masses typical of adults; body fat was essential for accelerated development. In nature, males may forego reproductive development until they can acquire adequate fat stores to survive hibernation and activate their reproductive system and until they gain social experience important in male–male competition for mates.


2006 ◽  
Vol 33 (4) ◽  
pp. 496-501 ◽  
Author(s):  
W. Ron DeHaven ◽  
Ruth Goldberg

Author(s):  
P. Milton

Observations in the field, and in the laboratory, of littoral fishes of south-west England during the period 1978–80 have shown that the three blenniid species found with any frequency on the shore constitute an important link in food chains. The occurrence, age, habitat and diet of Blennius (Lipophrys) pholis L., Coryphoblennius galerita L., and Parablennius gattorugine Brunnich have been considered; B. pholis was by far the most common of the three, with very few P. gattorugine being found intertidally. Of the latter, only age groups 0, 1 and 2 were represented in the littoral populations, whereas in the truly littoral species age groups 0–10 were found for B. pholis and 0–6 for C. galerita. Measurements of growth rates for the three species have been compared with growth rates of B. pholis and C. galerita at other sites, and a similar treatment has been afforded to dietary constituents. A discussion of the possible competition for food and refuge between the three species, and with other littoral teleosts, concludes that highly efficient partitioning of resources reduces competition to a minimum, with the exception of abundant food items which are (in any case) probably underexploited.


2013 ◽  
Vol 160 (10) ◽  
pp. 2755-2762 ◽  
Author(s):  
Mark J. Jessopp ◽  
Michelle Cronin ◽  
Thomas K. Doyle ◽  
Mark Wilson ◽  
Abigail McQuatters-Gollop ◽  
...  
Keyword(s):  

Behaviour ◽  
2016 ◽  
Vol 153 (1) ◽  
pp. 49-67 ◽  
Author(s):  
Eric S. Michel ◽  
Stephen Demarais ◽  
Bronson K. Strickland ◽  
Jerrold L. Belant ◽  
Joshua J. Millspaugh

Dominance is a behavioural mechanism that allows individuals to access and monopolize resources which should ultimately improve their fitness. Hierarchy strength should be strongest when resources are limited; however, this relationship is not consistent. We provided abundant food to assess whether hierarchy strength was consistent with resource abundance using 9 groups of captive female white-tailed deer (Odocoileus virginianus). We further assessed how body mass, age and testosterone levels were associated with rank position. Deer displayed a weak hierarchy with a mean linearity () of 0.39 (SD = 0.09) and a mean directional consistency index of 0.83 (SD = 0.06). Rank was related to body mass (, slope = 0.011), but not age or testosterone levels (). We demonstrate that hierarchy strength was weak in the presence of abundant food resources and suggest the possibility that dominance is a plastic behaviour that may vary with resource abundance.


1980 ◽  
Vol 7 (3) ◽  
pp. 317 ◽  
Author(s):  
RJ Taylor

In an area of coastal lowland managed by the Forestry Department of Queensland, habitats differed in the density, height and species composition of their undergrowth. In natural habitats Themeda australis made up the bulk of the diet of M. giganteus, but in firebreaks a range of grasses was eaten. Kangaroos actively fed only in habitats with open undergrowth, and in these habitats the density of faecal pellets correlated with the abundance of food present. Dense undergrowth restricted use of habitat even for movement. The abundance of food and the height and density of the undergrowth in contiguous habitat influenced the abundance of sightings on firebreaks. Firebreaks create a new source of abundant food. Prescribed burning attracts kangaroos to habitats by opening up dense undergrowth and encouraging the growth of grass.


1976 ◽  
Vol 27 (3) ◽  
pp. 499 ◽  
Author(s):  
RG Chittleborough

Fertilization of eggs is external: the female does not need to be newly moulted to be mated. The incubation period of eggs (19-68 days) varied inversely with water temperature, being longest at 19� C and shortening towards an asymptote at 25� C. Most adult females breed every year. When given abundant food, 77% of those breeding in aquaria at ambient temperature had two successive spawnings in a breeding season, whereas in a relatively crowded part of the natural population less than 12% of the breeding females spawned twice in a season. When held at a constant temperature of 25� C and given abundant food, adult females bred continuously, averaging six spawnings and three moults each year. In the natural population, size at first breeding and mean size of breeding females did not vary with depth but differed from one locality to another. At the Abrolhos Islands where the present density of breeding stock is highest, adults appear to be stunted and fecundity is relatively low. This situation may have existed to some extent in other parts of the population before heavy commercial fishing of the past 20 years or more reduced the density of the breeding stock to present levels. The operation of density-dependent regulation of fecundity in this population is discussed.


2012 ◽  
Vol 2012 ◽  
pp. 1-23 ◽  
Author(s):  
Paula E. Cushing

This paper provides a summary of the extensive theoretical and empirical work that has been carried out in recent years testing the adaptational significance of various spider-ant associations. Hundreds of species of spiders have evolved close relationships with ants and can be classified as myrmecomorphs, myrmecophiles, or myrmecophages. Myrmecomorphs are Batesian mimics. Their close morphological and behavioral resemblance to ants confers strong survival advantages against visually hunting predators. Some species of spiders have become integrated into the ant society as myrmecophiles or symbionts. These spider myrmecophiles gain protection against their own predators, live in an environment with a stable climate, and are typically surrounded by abundant food resources. The adaptations by which this integration is made possible are poorly known, although it is hypothesized that most spider myrmecophiles are chemical mimics and some are even phoretic on their hosts. The third type of spider-ant association discussed is myrmecophagy—or predatory specialization on ants. A table of known spider myrmecophages is provided as is information on their biology and hunting strategies. Myrmecophagy provides these predators with an essentially unlimited food supply and may even confer other protections to the spiders.


The Condor ◽  
1985 ◽  
Vol 87 (3) ◽  
pp. 430-431 ◽  
Author(s):  
Geoffrey S. Lebaron ◽  
Frank H. Heppner

2018 ◽  
Vol 3 (10) ◽  
pp. 31-37
Author(s):  
Man Kyu Huh

Species diversity varies dramatically among regions and among localities within regions.This study is to investigate the biodiversity of animal kingdoms at four regions on the Jungchon Stream in Korea. Mammals accounted for nine taxa for four seasons within the studied areas. Invertebrates exhibited the greatest species diversity with 17 taxa identified, followed by birds (Aves) (15 taxa). The mean numbers of species were 40 taxa within the St. A, 40 taxa within the St. B, 41 taxa within the St. C, and 44 taxa within the St. D. Many individuals of fish and invertebrates were found in this area because the abundant food and water supply by junction of two rivers.The mean of Shannon-Weaver index (H´) of diversity for mammals was varied from 1.170 (St. D) to 2.002 (St. A).St. A was also considerable high H´ in birds andreptiles/amphibians. Berger-Parker’s index (BPI) for mammalswas varied from 0.201 (Station A) to 0.294 (Station C).For the community as a whole, the values of ß-diversity were the low (from 0.170 for St. D to 0.232 for St. C). Clustering of four stations, using the NJ algorithm, was performed based on the matrix of calculated distances. Four stations of the Jungchon Stream were well separated each other.


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