Use of Wetland and Deepwater Habitat by Wintering Sandhill Cranes in Coastal Texas

Abstract

es, coastal prairie, scrub oak brushland, and harvested grain fields (Guthery, 1975). Sandhill cranes roost on shallow open water marshes in coastal Texas (Guthery, 1975), saline lakes in west Texas (Iverson et al., 1985), and shallow rivers and lakes in New Mexico (Walker and Schemnitz, 1987). However, data are lacking on the types of wetlands and deepwater habitats important to sandhill cranes. Low recruitment rates in the mid-continent population emphasize the need for close monitoring of populations and habitats (Tacha et al., 1992). Our objective was to determine the most important wetland and deepwater habitat types, based on density, for wintering sandhill cranes along the Texas Gulf Coast. We conducted the study from Galveston Bay, Texas south to the Rio Grande River, an area of 55,000 km2 (Anderson et al., 1996, 1998). This area corresponds to the region occupied by the Gulf Coast subpopulation of sandhill cranes (Tacha et al., 1992). The region is predominantly rice fields and coastal marsh in the northeast and coastal prairie and sandy plains in the southeast (Anderson et al., 1996). Palustrine and estuarine wetlands and deepwater habitats (Cowardin et al., 1979) are common (Muehl et al., 1994). We conducted ground surveys of all flooded wetlands and deepwater habitats on 512 randomly located, 64.75-ha plots in 1991-1992 and 1,009 plots in 1992-1993 (Anderson et al., 1996, 1998) for sandhill cranes. Surveys were conducted throughout the day during 2 week periods in September, November, January, and March as part of a larger project investigating habitat use by other waterbirds (Anderson, 1994; Anderson et al., 1996), waterbird abundance (Anderson et al., 1998), and wetland abundance (Muehl et al., 1994). The wetlands surveyed are representative of habitat conditions and wetland types found throughout most of the Gulf Coast (Anderson, 1994). All suitable habitat was surveyed for sandhill cranes to estimate populations (Anderson et al., 1998), but only cranes observed on wetlands and deepwater habitats are included in this paper. Few sandhill cranes were observed in September and March (Anderson, 1994), so we only present data for November and January. We classified all wetlands and deepwater habitats on plots according to Cowardin et al. (1979) by recording system, subsystem, class, and subclass. We recorded wetland size as the