Winter management of Californian rice fields for waterbirds

Abstract

Summary 0[ Recent legislation designed to reduce air pollution has restricted Californian rice! farmers from burning rice stubble after harvest[ Intentional~ooding of _elds during winter to speed straw decomposition is becoming increasingly common as growers seek alternatives to burning residual straw[ The potential for~ooded _elds to act as a surrogate for destroyed wetland habitat may be an additional bene_t in a region that hosts a large proportion of North America|s wintering waterbirds[ We investigated the degree to which waterbirds use~ooded _elds and whether the method of~ooding a}ects their use[ Speci_cally\ we tested whether waterbird use "a# was greater in intentionally~ooded _elds than in un~ooded _elds\ "b# di}ered among~ooded _elds receiving di}erent straw manipulations and "c# varied with water depth[ 1[ Intentionally~ooded rice _elds received signi_cantly greater use by 13 of 20 species studied[ Only great blue herons Ardea herodias and sandhill cranes Grus canadensis were signi_cantly more common in un~ooded _elds[ Geese densities did not di}er between~ooded and un~ooded _elds[ 2[ We found no di}erences in the densities of most species in~ooded _elds that received di}erent straw manipulations to improve decomposition rates[ Exceptions included several small shorebirds which occurred at highest densities in _elds where straw was incorporated into the soil[ 3[ Species di}ered in their use of di}erent water depths[ For 03 species we tested whether preferred depths\ suggested in the literature\ received disproportionately higher use[ Most of these species were more likely to be encountered within the suggested depth ranges[ Depth\ however\ was a poor predictor of bird density[ Depths of 04Ð19 cm resulted in frequent use by the greatest number of species[ 4[ We conclude that~ooding rice _elds increased suitable habitat for most\ but not all\ species studied[ Di}erent straw manipulation methods had little e}ect on most species[ Water depth\ however\ was important in determining species occurrence[ During the _rst half of the winter\ water depths were greater than the median depths used by most species[ Key!words] agriculture\ shorebirds\ waterfowl\ water depth\ wetland management[

Cross-Seasonal Patterns of Avian Influenza Virus in Breeding and Wintering Migratory Birds: A Flyway Perspective

“…The majority of losses have occurred in the CCV with disappearance of 90% of wetlands (Gilmer et al 1982). This is one of the most important rice-growing regions in the United States where natural habitat is now limited to managed wetlands such as wildlife refuges or rice fields that are flooded postharvest (Elphick and Oring 1998). This concentration of overwintering sites that support over 6 million birds each winter in the CCV (Reid and Heitmeyer 1995) may facilitate intermingling of different species originating from various breeding grounds, resulting in exchange of subtypes.…”

Long-term studies find benefits, challenges in alternative rice straw management

“…Researchers found lower waterbird densities in nonflooded fallow rice fields compared with flooded in California (Elphick and Oring 1998). Winter flooding demonstrated significant benefits for weed control, whether the field was burned or not.…”

Variação temporal na abundância de espécies de aves aquáticas em uma lagoa costeira do Norte Fluminense do estado do Rio de Janeiro, sudeste do Brasil

“…Nesse contexto, cada espécie seleciona a área com características bióticas e abióticas mais adequadas à sua sobrevivência e reprodução (SINCLAIR, 1989;ELPHICK;WELLER, 2003). Isso faz com que regiões com características mais apropriadas, em geral, suportem maior abundância de aves aquáticas (MA et al, 2010 BAIRLEIN, 2009;LUNARDI et al, 2012).…”