Temporal Patterns in Diet of Nestling White-Crowned Pigeons: Implications for Conservation of Frugivorous Columbids

Abstract

The timing and production of crop milk are important to the reproductive tactics of granivorous columbids, but little is known about crop-milk production in frugivorous columbids. We examined the diet of nestling White-crowned Pigeons (Columba leucocephala) and the relative contributions of crop milk and fruit during different stages of nestling development. The diet was dominated by five species of plants: Metopium toxiferum (poisonwood), Guapira discolor (blolly), Ficus citrifolia (shortleaf fig), F. aurea (strangler fig), and Erithalis fruticosa (black torch). Fruit of F. aurea and F. citrifolia dominated the diet during May and June. Fruit of M. toxiferum, which began to ripen in early July, dominated the diet through September. Guapira discolor was found in the diet throughout the nesting season and, overall, ranked as the second-most-important food. Erithalis fruticosa was found in small amounts in samples collected throughout the season. Crop milk remained an important component of the diet throughout the nestling period. As nestlings grew, fruit was added to the diet. At ages 0 to 2 days, the diet was entirely crop milk. The proportion of the diet composed of fruit increased from 10% on day 3 to 65% at day 15. These data suggest that the reproductive tactics of frugivorous pigeons may differ from those of granivorous pigeons. We speculate that frugivorous columbids may continue to supplement the diet of nestlings and fledglings with crop milk. Although this behavior may enhance growth rates and survival of individual young, it also may lengthen the interclutch interval. These findings emphasize the conservation importance of protecting large feeding areas to maintain populations of threatened and endangered frugivorous pigeons.