Meeting Abstract
Resource mobilization and reallocation is a major endpoint of the physiological response to acute stress. In mammals, a hyperglycemic response to acute stress is well characterized, however it is not consistently detectable in non-mammalian vertebrates. A hyperglycemic response to acute handling stress has been shown in some passerines including White-crowned Sparrows and White-throated Sparrows. Here we characterized the glycemic response to acute-handling stress in a breeding, free-living, population of Mountain Dark-eyed Juncos (Junco hyemalis) in Mono County, CA. Juncos were trapped in seed-baited potter traps at Tioga Pass Meadow from May 17 to June 20, 2018, coinciding with territory establishment and early nesting period. Blood samples were collected at 0, 15 and 30 min post-capture. We utilized a human blood glucose meter, FreeStyle Lite, to determine real-time glucose levels in the field, after previously validating this novel technique. Consistent with research in other sparrow species listed above, blood glucose levels were higher than baseline (time point zero) at 15 minutes (42.6% increase) and 30 minutes post-capture (66.7% increase). Additionally, predictors of glucose mobilization including: date, scaled body mass, fat score, hematocrit, sex, and bleed delay time were modeled using backward and forward stepwise regression. Analysis showed that Juncos mobilize glucose in response to acute handling stress and response is best modeled when scaled mass, hematocrit, and date are included as predictor variables. These results suggest that glucose mobilization capacity is influenced by measures of body condition including mass and hematocrit, and the response may fluctuate during the breeding season.
