Relationships of red-cockaded woodpecker reproduction and foraging habitat characteristics in Arkansas and Louisiana

Red-cockaded woodpecker (RCW; Picoides borealis) productivity is influenced by characteristics of forests in which they forage. Thus, we investigated the relationships between stand conditions and RCW reproduction. We conducted focal animal sampling two to three times per season for ten RCW groups from September 1999–September 2001 in southern Arkansas and northern Louisiana, USA. We measured overstory and understory vegetation characteristics associated with observed foraging sites. Mean diameter at breast height (DBH) of hardwood trees and autumn forb cover were inversely correlated with number of eggs laid. The numbers of eggs, hatchlings, and fledglings were similar between groups with and without helpers, though helpers tended to remain in higher quality habitat. Groups with helpers used foraging areas with greater basal area of pines (Pinus spp.) ≥25.4 cm DBH, conifer canopy cover, leaf litter cover, litter depth, autumn vine cover, and winter woody cover than groups without helpers. Our results suggested that foraging habitat recommendations should include understory conditions, although additional research is required to clarify the interrelationships between RCW reproduction, forest stand characteristics, and the arthropod community.     

Family composition and the characteristics of parental care during the nursing phase of captive common marmosets (Callithrix jacchus)

Cooperative care of the young by the father, older siblings, and unrelated group members is observed in a number of species, but inCallithrix jacchus parental care by the father is considered to be part of the reproductive behavior of the species. Nevertheless, the way the presence of potential helpers influences the costs of caring for the parents is not well understood. In this study we describe the suckling phase of youngC. jacchus, in families with and without older siblings, assessing the effect of siblings on the amount of care given by the father and mother. Six family groups were observed: three consisting of the mated pair and two newborn infants, and three with one or two additional sub-adult siblings. Our results suggest that the presence of older siblings as helpers affects the parents' participation in caregiving by altering maternal investment through the control of nursing and by reducing the costs of carrying for the father.