PHYSIOLOGICAL-RESPONSES OF NORTHERN BOBWHITE (COLINUS-VIRGINIANUS) TOCHRONIC WATER-DEPRIVATION

We tested the hypotheses that (1) chronic water deprivation could lend to reproductive failures in northern bobwhite (Colinus virginianus); (2) chronic water derivation would cause changes in levels of serum co rticosterone (B), progesterone (P), and osmolality; and (3) quail coul d acclimate to chronic water deprivation during the breeding season. Q uail were subjected to ad libitum, 75%, 50%, or 25% water restriction 11 wk during the spring-early summer breeding season. Additional birds were subjected to 50% or 25% ad libitum water restriction for 5 wk an d then given ad libitum water for 6 wk. In females water restriction i nhibited ovary and oviduct development which was reflected in a delay in egg production and a decline in egg mass. In males, water restricti on was associated with a decline in testis mass. Although the effects of water restriction were pronounced, they were quickly reversed with administration of ad libitum water after the initial 5 wk of treatment . Water-restricted female quail had reduced levels of serum P, but nor mal levels of B. In contrast, water-restricted males had normal P leve ls, and in the most severely water-deprived birds, elevated levels of B. We found serum osmolality to be consistently elevated in water-rest ricted males and females. Thus, unlike the serum hormone levels serum osmolality was consistently, and similarly changed in both sexes durin g water deprivation. Our results indicate that chronic water deprivati on could lead to reproductive failures in quail. However, the bird's a bility to continue laying eggs also indicates that it can partially ac climate to water deprivation during the breeding season to allow repro duction to proceed during periods of chronic drought.