Demographic Analysis of a Declining Northern Bobwhite Population in Southwestern Ohio

Gates, Robert J.; Janke, Adam K.; Liberati, Marjorie R.; Wiley, Mark J.

doi:10.7290/nqsp07rd00

Cited by 6 publications

(12 citation statements)

References 15 publications

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“…This strategy follows recommendations that range-wide recovery of northern bobwhite populations should focus on increasing usable space at the regional level by restoring native grasses and forbs with the assumption that populations are limited by reproduction (Burger et al 2006). This may be true in southern areas of bobwhite range but we have argued that bobwhite populations on our study areas (and possibly in other northern areas of bobwhite range) are most limited by protective cover near food sources during the nonbreeding season (Gates et al 2012). This is not to say that sustaining reproduction by providing adequate nesting and brood-rearing habitat is not essential to conserving bobwhite populations throughout their range.…”

Section: Usable Space Assessment For Bobwhites 79mentioning

confidence: 82%

“…nesting and protective cover types) which limits the capacity of a focal area to support bobwhite populations. Although capable of relatively long-distance dispersal during fall and spring ''shuffles'' , Smith 2015, bobwhites are vulnerable to predation when they move long distances between food and protective cover during winter, resulting in unsustainably low over-winter survival (Janke andGates 2012, Gates et al 2012).…”

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confidence: 99%

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Temporal and Spatial Assessment of Usable Space and Cover Type Interspersion for Northern Bobwhites on Private Farmlands in Southwestern Ohio

Gates

Wiley

Janke

et al. 2017

NQSP

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Contemporary landscape change driven by socio-economic forces and advances in agricultural technology do not favor northern bobwhites (Colinus virginianus) in the Midwestern United States. The challenge of bobwhite conservation is to provide sufficient quantities of habitat with optimal configurations in proportions that satisfy needs throughout the year on private-owned working lands. We radio-tracked 58 coveys and 98 individual birds throughout the year in 2009-10 and 2010-11 on privately owned farmland in southwestern Ohio. We investigated temporal changes in usable space from use-availability data. Estimated proportions of usable space based on analyses of habitat selection across four study sites were 0.06-0.12 during the non-breeding season compared to 0.10-10.30 during the breeding season. We also modeled probabilities that radio-marked coveys or individual birds used points within individual cover types as a function of distance to other cover types. Locations of radio-marked coveys and individual birds within focal cover types were closer to other cover types compared to random points during breeding (mean ¼ 44 m) and non-breeding (mean ¼ 58 m) seasons. Probability of use within focal cover types declined with distance to other cover types, typically falling below 50% when distances exceeded 9-242 m. Locations of radio-marked coveys were concentrated near edges within used cover types, while locations of individual birds were more dispersed during the breeding season. Estimated proportions of usable space based on distances between locations of radio-marked bobwhites and nearest cover types were higher (0.30-0.53) than estimates based on habitat selection ratios, and were similar between non-breeding and breeding seasons. Potentially usable sites were not fully occupied in either season, but there was no relationship between crude covey densities and proportions of usable space estimated from habitat selection analyses during the breeding and non-breeding seasons across study sites and years (r 2 , 0.166, P . 0.316). With distance to cover type estimates of usable space (years combined), two study sites with the highest proportions of usable space (0.43-0.53) also had the largest crude covey densities (0.0065-0.153 coveys/ha) compared to the other two sites with lower proportions of usable space (0.30-0.32) and smaller covey densities (0.004 -0.006 coveys/ha). Habitat enhancement should focus on providing protective cover near food for coveys during the non-breeding season and protective cover near nesting and brood-rearing habitat during the breeding season. Conserving Midwestern bobwhite populations requires innovative practices that can be implemented on private lands as economic incentives change for farm operators. Improving protective cover along habitat edges can increase usable space by improving cover type juxtaposition (e.g. food near cover) while minimizing impact on farming practices.

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Section: Usable Space Assessment For Bobwhites 79mentioning

confidence: 82%

mentioning

confidence: 99%

Temporal and Spatial Assessment of Usable Space and Cover Type Interspersion for Northern Bobwhites on Private Farmlands in Southwestern Ohio

Gates

Wiley

Janke

et al. 2017

NQSP

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“…The importance of woody cover to bobwhite during winter has been commonly reported , Gates et al 2012, Janke et al 2015. Janke et al (2015) also found that early-successional woody cover was the most influential driver of survival, specifically earlysuccessional woody cover, whereby woody-edge density with 95 m of the location was the largest contributor to winter survival.…”

Section: Discussionmentioning

confidence: 84%

“…Known fate, logistic exposure models (Dinsmore et al 2002, Shaffer 2004, Shaffer and Thompson 2007 are commonly used to estimate nest survival and survival of birds fitted with tracking devices (Matthews et al 2011, Gates et al 2012, Matthews et al 2012, Anich et al 2013. We assigned a covey identification number (covey ID) to each unique combination of individuals located within 50 meters of each other at the time of resighting.…”

Section: Survival Analysesmentioning

confidence: 99%

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Environmental drivers of Northern bobwhite fall and winter survival and resource selection in Southwest Missouri

Mosloff¹

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Northern bobwhite (Colinus virginianus) populations have declined over the last 50 years throughout the majority of their historical range, primarily due to habitat loss and degradation caused by modern farming practices, increased urbanization, succession of native grasslands to forests, decreases in native pasture acreage and increases in grazing intensity. Recent questions regarding conservation grazing and prescribed burning management regimes and extensive grassland management suggest further information on vegetation and management effects on bobwhite demographics is necessary for robust conservation planning. Information regarding the survival and resource selection through fall and winter is necessary to create a holistic management plan which benefits bobwhite at all stages of their annual cycle. Therefore, our objective was to determine the relationship of bobwhite survival and resource selection to vegetation types and management practices to fill in knowledge gaps of their annual cycle and demography. We used known-fate, logistic exposure survival models to estimate survival of birds fitted with tracking devices. We used 2068 bobwhite locations from 1 Nov to 31 Jan, 2017-2018 and 2018-2019 to fit 7 models that represented competing hypotheses concerning the amount of native grass, intensive and extensive management, and woody cover. Variation in survival was not explained by the amount of native grass managed by prescribed burning and grazing on the landscape. However, survival was negatively related to prescribed burning. Survival was negatively related to the distance to shrubs but not related to shrub edge density or proportion of shrub cover within 50 m. Survival was also positively related to the distance from the nearest tree. We used conditional multinomial logit discrete models to evaluate the relationship of vegetation and management types to bobwhite resource selection by comparing covariates among the used point and a set of random points that defined a choice set for each bobwhite location. We used 671 choice sets from 1 Nov 2018 to 31 Jan 2019 to fit 6 candidate models in a model selection framework which represented combinations of our hypothesized drivers of bobwhite fall and winter resource selection. We found no support for an effect of native warm season grasses or the effect of prescribed burning and grazing on resource selection. Bobwhite selected locations with greater woody stem counts and greater visual obstruction, both of which are indicative of shrub cover, and there was a weak positive relationship with woody edge density However, bobwhite also selected locations that were closer to trees. We found weak support for negative effects of the percentages of forb and bare ground at a given location on resource selection, while there was a negative effect of grass on winter resource selection. Woody cover was an important component of vegetation contributing to fall and winter survival and resource selection of bobwhite in Missouri. More specifically, proximity to shrubs and distance from trees were positively related to survival. Greater quantities of woody stems, indicative of shrub thickets also increased the relative probability of selection. Interestingly, closer proximity to trees also increased the relative probability of selection, potentially indicating an ecological trap. While necessary, the utility of native grasslands for bobwhite is greatly diminished if they do not contain shrub cover. Prescribed burning is perhaps the most effective tool to manage native grasslands for bobwhite habitat as it simultaneously promotes native grass quality, removes litter, and prevents shrub cover from dominating the landscape and succeeding to trees. While prescribed fire is important for controlling woody vegetation and for the creation of breeding, nesting, and brood rearing habitat, its short-term effect was to reduce survival of bobwhite in the fall and winter. We suggest that application of prescribed fire on short intervals at large scales will likely reduce the quality of habitat available to bobwhite during the fall and winter seasons. However, the use of fire in a multiyear rotation in combination with grazing in native and restored grasslands can create the needed interspersion of shrub cover for fall and winter while meeting the other annual resource needs of bobwhite. Felling mature trees while still maintaining adequate interspersion of shrubs may also prevent an ecological trap because survival was lower nearer trees. Lastly, while our study focused on fall and winter habitat, we suggest conservation planning and management needs to consider quail needs throughout their full annual cycle.

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The effects of habitat, weather, and raptors on northern bobwhite abundance at multiple spatial scales

Edwards,

Hernández,

Wester

et al. 2024

J Wildl Manag

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Rangelands in the southwestern United States represent a current stronghold for northern bobwhite (Colinus virginianus); however, bobwhite populations in rangelands exhibit extreme inter‐annual variability in abundance in relation to fluctuating weather patterns. Recent declining bobwhite population trends within this region have led to the supposition that landscape‐scale processes, such as habitat loss and fragmentation and predation from increased raptor abundance, may be acting in conjunction with weather to reduce bobwhite populations. Our objective was to determine the relative effects of these factors on bobwhite populations in the rangeland environments of Texas and Oklahoma, USA. We obtained publicly available datasets for bobwhite counts (Breeding Bird Survey, state‐agency roadside counts), weather (PRISM), land cover (National Land Cover Database), and raptors (Christmas Bird Counts) for 3 5‐year periods (1990–1994, 1999–2003, 2009–2013). Data were collected at route and landscape scales based on routes within the Rio Grande Plains region of Texas and the Central Mixed Grass Prairie region of Texas and Oklahoma. We used generalized linear mixed models with a backward selection approach to determine top models for each dataset based on scale and ecoregion. Covariate relationships with bobwhite abundance followed expected patterns, with positive relationships with habitat, precipitation, and minimum temperatures and negative relationships with maximum temperatures and raptor abundance. Weather variables were the factors most consistently selected within both regions, while minimum winter temperature was overall the top variable. These relationships occurred within a landscape still containing relatively vast amounts of unfragmented bobwhite habitat (>60% rangeland; >15 million ha). Management within these regions should be focused on retaining habitat at a broad scale, while managing for suitable cover at a local scale to help mitigate weather effects.

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Demographic Analysis of a Declining Northern Bobwhite Population in Southwestern Ohio

Cited by 6 publications

References 15 publications

Temporal and Spatial Assessment of Usable Space and Cover Type Interspersion for Northern Bobwhites on Private Farmlands in Southwestern Ohio

Temporal and Spatial Assessment of Usable Space and Cover Type Interspersion for Northern Bobwhites on Private Farmlands in Southwestern Ohio

Environmental drivers of Northern bobwhite fall and winter survival and resource selection in Southwest Missouri

The effects of habitat, weather, and raptors on northern bobwhite abundance at multiple spatial scales

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