HORMONES AND EXTERNAL FACTORS - ARE THEY ON OFF SIGNALS FOR MATERNAL NEST-BUILDING IN RABBITS/

Estradiol, progesterone, and prolactin regulate digging, carrying stra w, and plucking hair for maternal nest-building in rabbits. To explore whether external factors also modulate this process, we assessed whet her shaved pregnant rabbits with straw nests would collect their own, male, or synthetic hair for nest-building. Pregnant (but not estrous) does collected and used all hair types, indicating that hair-plucking can be bypassed and a nest constructed with ''alternative'' hair. Unsh aved pregnant does with straw nests also collected synthetic hair, ind icating that this behavior is not triggered by the absence of maternal hair. Yet, if hair-plucking/nest-building had occurred, hair-collecti ng was prevented, suggesting that an internally triggered ''drive'' wa s turned off by perceiving a built nest. When given only straw or hair , shaved pregnant does collected and used the material provided, indic ating that nest-building is internally driven and accomplished by usin g any available elements. When given both materials, increasingly more shaved does built straw nests across prepartum days 7 to 2. Straw-car rying declined thereafter, suggesting that perceiving a straw nest lim its the collection of such material. Hair-collecting was postponed unt il prepartum day I to postpartum day 2, indicating that: (a) mothers d istinguish between straw and hair and (b) hormonal factors regulate th e sequential selection of straw and then hair and when the change from straw to hair occurs. Maternal behavior was normal at parturition and for the next 4 days in a similar proportion of does among all experim ental groups. We conclude that hormones and external factors regulate nest-building by acting as ''on/off/on'' signals. (C) 1998 Academic Pr ess.