Ecological Investigation Of Common And Purple Gallinules On Lacassine National Wildlife Refuge, Louisiana

Ecological observations of gallinules on Lacassine National Wildlife Refuge from 1 April 1975 through 28 February 1976 indicate common gallinules (Gallinula chloropus) arrive earlier and begin nesting before purple gallinules (Porphyrula martinica). Eleven nests of common gallinules, characteristically positioned low in the vegetation and con· structed of bulltongue (Saggitaria lanci/olia), contained an average of 8.1 eggs. The more elevated nest of the purple gallinule contained an average of 4.5 eggs, in a sample size of 12, and was constructed primarily of maidencane (Panicum hemitomon). Common gallinule chicks form a tight cluster or grouping and follow the parent bird(s) along linear feeding paths. The more precocial purple gallinule chicks form a more dispersed aggregation around the parent(s) which feed in circular patterns. Within the first 10 days of hatching mortality may be as high as 40% for common and 30% for purple gallinules. The total combined population of gallinules on Lacassine Pool is estimated to be 31,000 individuals in late summer.

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