Breeding Waterbird Use of Louisiana Rice Fields in Relation to Planting Practices

Rice (Oryza sativa) fields are managed wetlands that have high potential value to wildlife, especially waterbirds. To better understand factors influencing use of rice fields by breeding waterbirds, we compared nest densities in waterand dry-seeded rice fields in southwestern Louisiana, May-July 1993. Densities of waterbird nests in dry- and water-seeded plots were similar (paired t = 0.69, df = 13, P = 0.505). Minimum density of waterbird nests surveyed in Louisiana rice fields averaged (±SE) 37.2 ± 4.4 nests/km2 (N = 28, range = 0-92.7). Nests of king rails (Rallus elegans, 15.9 ±3.1 nests/km2), fulvous whistling ducks (Dendrocygna bicolor, 15.1 ± 3.3 nests/km2), and purple gallinules (Porphymla martinica, 5.1 ± 1.4 nests/km2) were common, but common moorhen (Gallinula chloropus) and least bittern (Ixobrychus exilis) nests were rare (< 1 nest/km2). Waterbird nesting densities tended to be greater in "dense" than in "less dense" stands of rice (paired t = 2.08, df= 13, P = 0.058). Densities of waterbird nests were not affected by planting practices during the year of study, but hatching success of fulvous whistling ducks might be greater in water- than in dry-seeded rice fields. Further study is required to clarify effects of planting practices on nesting success of waterbirds and survival of young in rice fields. Research also is needed to better understand factors influencing waterbird use of rice fields throughout the planting cycle and in other rice growing areas. Such information is essential for developing management options for rice cultivation that maximize benefits to both producers and waterbirds.

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