scholarly journals Decoupling the effects of food and density on life‐history plasticity of wild animals using field experiments: Insights from the steward who sits in the shadow of its tail, the North American red squirrel

2020 ◽  
Vol 89 (11) ◽  
pp. 2397-2414
Author(s):  
Ben Dantzer ◽  
Andrew G. McAdam ◽  
Murray M. Humphries ◽  
Jeffrey E. Lane ◽  
Stan Boutin
1995 ◽  
Vol 73 (6) ◽  
pp. 1115-1122 ◽  
Author(s):  
Karl W. Larsen ◽  
Stan Boutin

If territory quality affects the fitness of its holder, then relatively unsuccessful individuals should relocate if given the opportunity to appropriate a higher quality territory. Relocation by these animals, however, may be prevented by habitat saturation, poor competitive ability, or the costs of relocating. We conducted two removal studies that created numerous territory vacancies in a population of the North American red squirrel (Tamiasciurus hudsonicus), thus providing favourable conditions for relocation. In both experiments, we tested whether nonbreeding females were more likely to relocate than breeding females, presumably because they (the nonbreeders) occupied relatively poor-quality territories. In our first experiment we permanently removed most of the squirrels from a study site and monitored the relative proportions of the remaining nonbreeding and breeding females that relocated. In our second experiment we monitored the response of squirrels to vacant territories that had been previously held by nonbreeding and breeding females, as well as by males. We also monitored the behaviour of squirrels that did not hold territories (dispersing offspring), as these individuals would not experience the same costs of relocation as adults. Our experiments showed that neither category of female was likely to relocate, regardless of the type of territory available. Both residents and dispersing offspring displayed no biases towards vacant territories that previously belonged to nonbreeding or breeding females or to males. Relocation does not appear to be a strategy for a female in this system to increase her reproductive opportunities. This suggests that either territory quality is inconsequential or the costs of relocation are prohibitive. Dispersing offspring also may be unable to select certain territories because of the premium placed on acquiring a territory, regardless of its quality.


Science ◽  
1931 ◽  
Vol 73 (1901) ◽  
pp. 620-621
Author(s):  
Emery Westervelt Dennis

1987 ◽  
Vol 6 (1) ◽  
pp. 57-62 ◽  
Author(s):  
R. N. Bamber

Abstract. A population of the North American myodocopid ostracod Sarseilla zostericola Cushman has become established in the River Medway, Kent, in the vicinity of the cooling water discharge from Kingsnorth Power Station, though not living in the thermally stressed regions of the discharge environment. The species is assumed to have been introduced with North American oysters, but is not an example of an ‘exotic’ species surviving in association with the heated discharge. The Kingsnorth individuals are larger and more fecund than those of studied North American populations. The breeding biology, life history and sex ratio are discussed. It is suggested that the intolerance of S. zostericola to the conditions of the thermally stressed discharge canal is associated with shell physiology.


1964 ◽  
Vol 96 (1-2) ◽  
pp. 159-159
Author(s):  
H. J. Teskey

Relatively little is known of the life history, ecology and behaviour of most species of Tabanidae. Knowledge of their immature stages is particularly deficient. The larvae of only 46, or about ⅛, of the North American species have been described and many of these descriptions are inadequate. The present research was initiated in 1960 to describe and classify tabanid larvae and to contribute information on larval habitats and life histories.


Evolution ◽  
1996 ◽  
Vol 50 (5) ◽  
pp. 2023 ◽  
Author(s):  
Thomas F. Turner ◽  
Joel C. Trexler ◽  
David N. Kuhn ◽  
Henry W. Robison

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