One explanation for the failure of intensively monitored Puerto Rican Parrot nests is that observers may lack the information needed to evaluate pair behavior and to recognize behaviors indicative of nest problems. I examined the behavior of Puerto Rican Parrots during eight non-problematic and six problematic nesting attempts to 1) describe behavior of pairs that experienced no notable nest problems and 2) to identify and describe behaviors associated with nest problems. I examined nest attendance, duration of attentive periods, and frequency of nest visits for both males and females, and duration of periods away from the nest for females only. Adult behavior during incubation and early chick rearing at non-problematic nests was well-defined. Females spent an average of 93.2 to 97.3% of the observation period in their nests during incubation and generally left their nests for average periods of 5 to 12 min. Female nest attendance generally declined and recesses became longer as chick rearing progressed. Males rarely entered their nests during incubation, but they generally established a regular pattern of nest visits within seven to 10 days of hatching of their young. In some cases, incidents of human disturbance to nest pairs during incubation and early chick rearing were associated with sudden changes in behavior. The key indicator of nest problems (abandonment during incubation or loss of young) was unexpected declines in female nest attendance. Declines were often accompanied by unexpected increases in female recesses or frequency of female nest visits, and sometimes by increases in male nest visits. Abandonment of nests during incubation was associated with repeated incidents of potentially disturbing activities (e.g., nest inspections). Deaths of embryos and young were associated with behaviors that allowed increased cooling of embryos.
