Herring, Garth

Model
Digital Document
Description
Stress proteins offer a measure of stress in birds at the cellular level that are an
alternative to the glucocorticoids. Stress proteins are not biased by handling stress, the
increase in stress proteins lasts longer than with other measures (e.g., corticosterone),
and, therefore, they may be a more appropriate measure of long-term or chronic stress.
However, caution should be practiced when using stress proteins because the level of
stress needed to elicit a response may be higher than with corticosterone. Stress
proteins have only recently been used to measure the response to competition, food
limitation, growth, and parasitism in birds. In other taxa, the stress proteins have been
used to measure genetic stress, temperature, toxins, UV radiation, and physical activity.
Stress proteins increase the options available to avian ecologists for understanding how
avian species respond to changes in the environment.
Model
Digital Document
Description
The physiological condition of juvenile birds can be influenced by multiple ecological stressors, and few studies have
concurrently considered the effects of environmental contaminants in combination with ecological attributes that can
influence foraging conditions and prey availability. Using three temporally distinct indices of physiological condition, we
compared the physiological response of nestling great egrets (Ardea alba) and white ibises (Eudocimus albus) to changing
prey availability, hydrology (water depth, recession rate), and mercury exposure in the Florida Everglades. We found that the
physiological response of chicks varied between species and among environmental variables. Chick body condition (shortterm
index) and fecal corticosterone levels (medium-term) were influenced by wetland water depth, prey availability, region,
and age, but not by mercury contamination. However, mercury exposure did influence heat shock protein 70 (HSP70) in
egret chicks, indicating a longer-term physiological response to contamination. Our results indicate that the physiological
condition of egret and ibis chicks were influenced by several environmental stressors, and the time frame of the effect may
depend on the specialized foraging behavior of the adults provisioning the chicks.