|
     
| |
|
Energy and Water Balance
of Larks Vary with Life History Along an Aridity Gradient
 
As part of our ongoing investigations of the physiology
of desert birds, we compared physiological, demographic and ecological
variables of species of larks across an aridity gradient from the deserts
of Saudi Arabia, to semi-arid regions of Spain, to the cool moist
grasslands of Netherlands. One of our goals was to gain insights into the
linkages between life history characters, such as clutch size and nestling
growth rate, and physiology. Quantifying field metabolic rate (FMR) and
water influx rate (WIR), using doubly labeled water, of parents feeding
nestlings, we found that parental FMR and WIR decreased with increasing
aridity. As the environment became more arid, nestling growth rate, clutch
size, the number of clutches laid per season all declined, whereas
predation rates increased. These
results support the idea that decreasing food and water availability in
desert environments favor lower energy and water requirements of parents
and young, reduced nestling growth rates and smaller clutch sizes (see
Tieleman et al. 2004).
|
|
Conservation
physiology of desert ungulates
We have worked with the government of
Saudi Arabia
in conjunction with the National Geographic Society to characterize the
physiology of desert ungulates that occupy the
Arabian Peninsula
. As air temperatures continue to increase across our globe, the question
arises how animals will be able to cope with this warming, especially in
the deserts of
Arabia
where predictions suggest an increase of 2-5 oC over the next
50 years. Our studies have been instrumental in developing conservation
strategies for the Arabian Oryx, an endangered ungulate of the
Arabian Desert
(Tredyte et al. 2001). One of our studies involved monitoring the body
temperature of sand gazelles over the course of a year using miniature
data loggers (Ostrowski and Williams 2006). We discovered that these
small endotherms allow their body temperature to increase during the day
and decrease at night during summer, a pattern called heterothermy, which
is thought to conserve considerable evaporative water.
|
|
| | |
