test Browse by Author Names Browse by Titles of Works Browse by Subjects of Works Browse by Issue Dates of Works
       

Advanced Search
Home   
 
Browse   
Communities
& Collections
  
Issue Date   
Author   
Title   
Subject   
 
Sign on to:   
Receive email
updates
  
My Account
authorized users
  
Edit Profile   
 
Help   
About T-Space   

T-Space at The University of Toronto Libraries >
University of Toronto at Scarborough >
Biological Sciences >
Biology >

Please use this identifier to cite or link to this item: http://hdl.handle.net/1807/353

Title: Why are arctic ground squirrels more stressed in the boreal forest than in alpine meadows?
Authors: Hik, David S.
McColl, Carolyn J.
Boonstra, Rudy
Keywords: Arctic ground squirrels
hypothalamic-pituitary-adrenal axis
predation risk
stress
sublethal effects
Issue Date: 2001
Citation: Ă‰coSCIENCE 8 (3) : 275-288 (2001)
Abstract: Arctic ground squirrels (Spermophilus parryii plesius Richardson) in the southeastern Yukon live in both boreal forest and alpine tundra habitats. We live-trapped young male and female squirrels in both habitat types and subjected them to a standardized hormonal-challenge protocol to assess the responsiveness of their hypothalamic-pituitary-adrenal axis. Alpine squirrels had levels of free cortisol at the baseline (initial) bleed following their removal from traps that were 3 times higher in males and 5 times higher in females compared with boreal forest squirrels. Females, but not males, from the boreal forest were dexamethasone resistant, while neither sex from the alpine habitat was resistant. Free cortisol in alpine squirrels also responded more dramatically after the injection of adrenocorticotropic hormone. Corticosteroid-binding globulin levels were significantly lower in forest than alpine squirrels and these levels were not markedly affected by the challenge protocol. Glucose levels were significantly higher in boreal than alpine squirrels and the pattern differed between the two sites in response to the protocol. Hematocrits were significantly higher in alpine squirrels. Collectively, this evidence suggests that Arctic ground squirrels were more chronically stressed in the boreal forest than in the alpine meadows. The most likely explanation for our results is higher predation risk in the forest compared with alpine meadows, as forage availability and population density were not significantly different between the two habitats.
URI: http://hdl.handle.net/1807/353
Appears in Collections:Biology

Files in This Item:

File Description SizeFormat
Hik.mccoll.boonstra.ecoscience.pdf116.14 kBAdobe PDF
View/Open

Items in T-Space are protected by copyright, with all rights reserved, unless otherwise indicated.

uoft