Mechanism of parasite rejection in two members of the family Mimidae
Original theory stated that avian hosts of parasitic Brown-headed Cowbirds (Molothrus ater) were clearly classified as an acceptor or rejector of parasitic eggs. Recent work forces reconsideration of this statement. Northern Mockingbird (Mimus polyglottos) rejection was reported at 60%. Percent rejection by the Brown Thrasher (Toxostoma rufum) has been documented at both 58% and 96%. The objective of this study is to determine proximate mechanisms involved in Northern Mockingbird and Brown Thrasher response to parasitic eggs of the Brown-headed Cowbird by testing if habitat suitability influences the likelihood of rejection, if host brood size influences rejection frequency, and if egg coloration influences the probability of rejection. During the summer of 2005 model cowbird eggs were placed in the nests of brooding Mimids across northeast Louisiana. Thirteen Brown Thrasher nests were parasitized. The model or real cowbird egg was ejected at each nest. Nine Northern Mockingbird nests were artificially parasitized. Six birds ejected the egg within two days. Of the final three, one nest was predated on day three and the final two nests were abandoned. No significant interaction has been found between habitat suitability, brood size, egg coloration and rejection of the parasitic egg. A second field season will begin in April 2006 with the objective of obtaining a larger sample size and exploring the action of ejection versus abandonment in the Northern Mockingbird. Data collected will improve our understanding of proximate response mechanisms to avian brood parasitism.
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Avian Biodiversity Study of Boeuf Wildlife Management Area
Avian populations of multiple forest treatment types within the Mississippi Alluvial Valley: A breeding bird survey of Boeuf Wildlife Management Area.
State Wildlife Grants were created to facilitate the development of a Comprehensive Wildlife Conservation Strategy within each state. These strategies seek to incorporate non-game species and species of conservation concern into traditional management plans originally directed towards game species. With 75% of the original forest cover in bottomland hardwoods lost, breeding birds of the Mississippi Alluvial Valley (MAV) warrant our conservation efforts. To understand how silviculture management techniques in bottomland hardwood forests impact avian populations, the Louisiana Department of Wildlife and Fisheries commissioned breeding bird surveys on selected state owned wildlife management areas (WMA). For this study breeding bird surveys were conducted from April 2005 through the first week of July 2005 at Boeuf Wildlife Management Area, located in Caldwell and Catahoula parishes of northeast Louisiana. A total of 189 point counts were conducted on 22 transects in treated and untreated forests as well as young hardwood plantations. Relative abundance, species richness and diversity were compared across silviculture treatments. A list of confirmed breeding birds (N=21) on the WMA has been generated as well as a checklist of all avian species encountered (N=173) to include those detected outside the constraints of the survey for use by citizen birders and the general public. A second field season will begin in April 2006. This study is supported by funds provided by LDWF & USFWS, Division of Federal Aid through State Wildlife Grants Program.
Checklist of Birds of Boeuf WMA
Exploring environmental concerns within biodiversity and sustainability, avian conservation, habitat restoration, the role of birding as a medium for environmental awareness and education.
