FACTORS INFLUENCING NEST SURVIVAL OF MOURNING DOVES IN THE LOWER RIO GRANDE VALLEY, TEXAS

Abstract

In the United States, mourning doves (Zenaida macroura) are harvested more than all other game birds combined. In the Lower Rio Grande Valley of South Texas, mourning doves nest in citrus and remnant woodland habitats, both of which are decreasing in the region. The objectives of this study were to compare nest survival between woodland and citrus land cover types and to model the influence of habitat characteristics and observer disturbance on nest survival. In 2016, we located 100 nests in four citrus groves (n = 21) and two woodlots (n = 79) in Hidalgo and Cameron counties, Texas. We monitored nests every 3 days and collected nest site vegetation measurements. We used logistic-exposure and Akaike information criterion model selection to determine which environmental and temporal variables best predicted nest survival. Candidate models included temporal variables and nest concealment variables such as overhead cover, side cover, distance to foliage edge, and vertical density below the nest. We found considerable differences in the vegetation structure between citrus and woodland sites. Density of vegetation below the nest was the best predictor of survival. Our results suggest that nest survival is higher in citrus groves likely because of increased cover below, to the side, and above nests. Although not considered native habitat, citrus groves might mitigate the loss of native woodland for mourning doves. Thus, the conversion of citrus agriculture to urban areas and row cropping should trouble wildlife managers in the region. Breeding mourning dove populations may be negatively affected by the loss of citrus and woodland land cover that has occurred over the last 50 years.