Steve K. Sherrod

Habitat Edge, Land Management, And Rates Of Brood Parasitism In Tallgrass Prairie

Bird populations in North Americas grasslands have declined sharply in recent decades. These declines are traceable, in large part, to habitat loss, but management of tallgrass prairie also has an impact. An indirect source of decline potentially associated with management is brood parasitism by the Brown-headed Cowbird (Molothrus ater), which has had substantial negative impacts on many passerine hosts. Using a novel application of regression trees, we analyzed an extensive five-year set of nest data to test how management of tallgrass prairie affected rates of brood parasitism. We examined seven landscape features that may have been associated with parasitism: presence of edge, burning, or grazing, and distance of the nest from woody vegetation, water, roads, or fences. All five grassland passerines that we included in the analyses exhibited evidence of an edge effect: the Grasshopper Sparrow (Ammodramus savannarum), Henslows Sparrow (A. henslowii), Dickcissel (Spiza americana), Red-winged Blackbird (Agelaius phoeniceus), and Eastern Meadowlark (Sturnella magna). The edge was represented by narrow strips of woody vegetation occurring along roadsides cut through tallgrass prairie. The sparrows avoided nesting along these woody edges, whereas the other three species experienced significantly higher (1.9-5.3x) rates of parasitism along edges than in prairie. The edge effect could be related directly to increase in parasitism rate with decreased distance from woody vegetation. After accounting for edge effect in these three species, we found evidence for significantly higher (2.5-10.5x) rates of parasitism in grazed plots, particularly those burned in spring to increase forage, than in undisturbed prairie. Regression tree analysis proved to be an important tool for hierarchically parsing various landscape features that affect parasitism rates. We conclude that, on the Great Plains, rates of brood parasitism are strongly associated with relatively recent road cuts, in that edge effects manifest themselves through the presence of trees, a novel habitat component in much of the tallgrass prairie. Grazing is also a key associate of increased parasitism. Areas managed with prescribed fire, used frequently to increase forage for grazing cattle, may experience higher rates of brood parasitism. Regardless, removing trees and shrubs along roadsides and refraining from planting them along new roads may benefit grassland birds.

Genetic variation within and among fragmented populations of lesser prairie-chickens (Tympanuchus pallidicinctus).

As a result of recurrent droughts and anthropogenic factors, the range of the lesser prairie‐chicken (Tympanuchus pallidicinctus) has contracted by 92% and the population has been reduced by approximately 97% in the past century, resulting in the smallest population size and most restricted geographical distribution of any North American grouse. We examined genetic variation through DNA sequence analysis of 478 base pairs of the mitochondrial genome and by assaying allelic variation at five microsatellite loci from lesser prairie‐chickens collected on 20 leks in western Oklahoma and east‐central New Mexico. Traditional population genetic analyses indicate that lesser prairie‐chickens maintain high levels of genetic variation at both nuclear and mitochondrial loci. Although some genetic structuring among lesser prairie‐chicken leks was detected within Oklahoma and New Mexico for both nuclear and mitochondrial loci, high levels of differentiation were detected between Oklahoma and New Mexico populations. Nested‐clade analysis of mitochondrial haplotypes revealed that both historic and contemporary processes have influenced patterns of haplotype distributions and that historic processes have most likely led to the level of differentiation found between the Oklahoma and New Mexico populations.

Lesser Prairie-Chicken Hen and Brood Habitat Use on Sand Shinnery Oak

Abstract The structural attributes of shrubland communities may provide thermal refugia and protective cover necessary for wild animals to survive. During the summers of 2002 and 2003, we evaluated the thermal environment for lesser prairie-chicken (Tympanuchus pallidicinctus Ridgway) broods in southeast New Mexico across a complex landscape that included grazed sand shinnery oak (Quercus havardii Rydb.), ungrazed sand shinnery oak treated with tebuthiuron, sand dunes, cropland, and Conservation Reserve Program native grass plantings. Based on data from 257 brood locations and 53 random locations, lesser prairie-chicken broods selected locations based on sand shinnery oak dominance, with taller plant heights and more over-head cover, when temperatures exceeded 26.4°C than what was randomly available. Prairie chickens selected areas not treated with herbicide and these sites were often selected at a fine spatial scale. These data support other studies suggesting that there may be no justification of shrub control for lesser prairie-chicken conservation within the sand shinnery oak communities.

SURVEY FOR RETICULOENDOTHELIOSIS VIRUSES IN WILD POPULATIONS OF GREATER AND LESSER PRAIRIE-CHICKENS

Abstract Reticuloendotheliosis (RE) is a viral disease documented from poultry, which has been found to cause mortality in captive Attwaters (Tympanuchus cupido attwateri) and Greater (T. c. pinnatus) prairie-chickens. We surveyed blood samples from 354 Greater Prairie-Chickens from seven states collected during 1998, 1999, and 2000, and from 184 Lesser Prairie-Chickens (T. pallidicinctus) from three states during 1999 and 2000, for the presence of RE virus proviral DNA using a polymerase chain reaction (PCR) test. All samples were negative for the presence of RE virus proviral DNA except for two samples collected from male Greater Prairie-Chickens taken in Oklahoma during 1998. This suggests that RE may not be a serious problem for most wild populations of prairie-chickens. Although our results were largely negative, because of the serious consequences of RE, the presence of the disease in wild populations of prairie-chickens should be carefully considered in any future relocation and reintroduction efforts.

Reducing grouse collision mortality by marking fences (Oklahoma).

A number of grouse species collide frequently with power y~Vlines, overhead cables, and fences. Because grouse fly fast these collisions are often immediately fatal, but likely a considerable number of birds either succumb later to injuries or become incapacitated and more vulnerable to predation. A multiyear radio-tracking study of the lesser prairie-chicken (Tympanuchuspallidicinctus) in Oklahoma found that collisions, primarily with stock fences, were the leading cause of mortality (WoUe et al. 2007). Several other species of grouse, including the greater sage-grouse (Centrocercus urophasianus) in North America and black grouse (Tetrao tetrix) and western capercaillie {Tetrao urogallus) in Europe, also suffer high mortality rates because offence collisions (e.g., Catt et al. 1994). In an effort to reduce this unnatural mortality, we explored various ways of marking fences to improve their visibility. Ideal marking material would be easily affixed, inexpensive, durable, and safe for livestock, and would add little or no weight or wind resistance to fences.

Growth and recovery of the bald eagle population in Oklahoma

Abstract We conducted surveys twice annually from 1990–2003 to determine the occupancy and reproductive success of known and newly reported bald eagle (Haliaeetus leucocephalus) nests in Oklahoma. During the study period, the number of nesting pairs of eagles increased from 0 to 41, and the number of young fledged per nest has remained between 1 and 2. The population and productivity level of bald eagles appear sufficient to declassify the species from its current listing as a federally threatened and state endangered species in Oklahoma.

JUVENILE LESSER PRAIRIE-CHICKEN GROWTH AND DEVELOPMENT IN SOUTHEASTERN NEW MEXICO

Abstract We examined growth rates and physical development of four body characteristics (mass, wing chord, bill length, and head width) of Lesser Prairie-chickens (Tympanuchus pallidicinctus) 3 to 111 days post-hatch in southeastern New Mexico. Growth rates, inflection points, and selected growth curves (logistic and Gompertz) associated with body mass and wing chord were similar between Lesser Prairie-chickens in New Mexico and Kansas. The asymptotic body mass (713 ± 7 g) was less for female and male yearling Lesser Prairie-chickens in New Mexico than for either yearling females or males in Kansas (male: 789 ± 4, female: 719 ± 6). Juvenile Lesser Prairie-chickens in New Mexico achieved 90% of their asymptotic body mass 7 days faster than Lesser Prairie-chickens in Kansas.