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Evidence for Regionally Synchronized Cycles in Texas Quail Population Dynamics
Author(s) -
LUSK JEFFREY J.,
GUTHERY FRED S.,
PETERSON MARKUS J.,
DEMASO STEPHEN J.
Publication year - 2007
Publication title -
the journal of wildlife management
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.94
H-Index - 111
eISSN - 1937-2817
pISSN - 0022-541X
DOI - 10.2193/2005-729
Subject(s) - colinus , ecoregion , quail , wildlife , bobwhite quail , population , population cycle , habitat , geography , abundance (ecology) , breeding bird survey , annual cycle , ecology , biology , demography , predation , sociology
Knowledge of the possible role of cyclic behavior in wildlife dynamics assists in understanding and managing populations. Using spectrum, we analyzed time series (1978‐2002) on the abundance of northern bobwhites ( Colinus virginianus ) and scaled quail ( Callipepla squamata ) in several ecological regions in Texas, USA, to test for the presence of cycles; we also tested whether drought severity (Modified Palmer Drought Severity Index) exhibited cyclic dynamics and whether quail and drought cycles were synchronized among regions. We found evidence of population cyclicity in all ecoregions we tested (5 for bobwhites, 4 for scaled quail) based on both Texas Parks and Wildlife and North American Breeding Bird Survey count data. Periods of the observed cycles generally were 5‐6 years (bobwhites) or 2‐3 years (scaled quail), depending on ecoregion and data source. Cyclicity was most pronounced for bobwhites in the Rolling Plains (north TX) and the South Texas Plains. The Palmer Index exhibited a roughly 5‐year cycle in 5 of 6 regions we tested. A 5‐year bobwhite and Palmer Index cycle were synchronous in 3 contiguous ecoregions totaling 27,200,000 ha. Wet‐dry cycles seemed to synchronize bobwhite cycles in Texas. Our results suggest that habitat manipulations aimed at improving habitat conditions during dry periods, such as reducing livestock stocking rates, could provide ground cover similar to that available in wet periods.