Habitat influences Northern Bobwhite survival at fine spatiotemporal scales

Janke, Adam K.; Gates, Robert J.; Terhune, Theron M.

doi:10.1650/condor-14-115.1

Cited by 25 publications

(39 citation statements)

References 65 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The deleterious effects of winter weather on bobwhite survival and population growth is established (Janke et al , ). We observed lower survival during winter periods in our study compared to other seasons and other studies (Sandercock et al ).…”

Section: Discussionmentioning

confidence: 99%

Broadcast supplemental feeding and northern bobwhite demographics in Texas

et al. 2018

View full text Add to dashboard Cite

Northern bobwhite (Colinus virginianus) abundance is declining. Food limitations have been hypothesized to exacerbate the boom and bust cycle exhibited by bobwhites, with supplemental feeding advocated as a way to mitigate this annual variability in demographics. A new technique (i.e., broadcast feeding) has exhibited positive effects on the seasonal survival of bobwhites. To ensure the safe adoption of any management practice, replication is necessary. We employed a randomized, crossover experimental design to evaluate the effect of 3 different supplemental feed rates (full [69.1 kg/km], half [34.6 kg/km], control [no feed]) on bobwhite survival and used the known‐fate data type to assess the fate of radio‐marked individuals within the Rolling Plains of Texas, USA. We assessed temporal (biological vs. calendar season) and treatment‐level (feed vs. control) effects on survival. Our top temporal model included an interaction between year and calendar season as the most parsimonious model. Survival was lowest during winter. The most parsimonious treatment‐level model included an interaction between feed and winter, plus the additive effect of snow depth. The application of the full and half feed treatments had positive effects on survival during winter compared to control units in both years, across all pastures. Our data indicated there was no difference between the full and half feed rates. Snow accumulation had a negative effect on survival in both years. Broadcast feeding improved winter survival rates and subsequently, the number of females available entering the breeding season. Broadcast feeding serves as an additional management tool for wildlife managers within a strategic management program to benefit bobwhite survival during periods of physiological stress. We recommend the continued use of this management technique in regions where similar range and weather conditions exist to further evaluate its effectiveness. © 2018 The Wildlife Society.

show abstract

Section: Discussionmentioning

confidence: 99%

Broadcast supplemental feeding and northern bobwhite demographics in Texas

et al. 2018

View full text Add to dashboard Cite

show abstract

“…Finally, the value of dense grass may only be apparent during harsh weather events (Janke et al. ), a relationship that may be elucidated with more data across years of varying weather and grassland conditions.…”

Section: Discussionmentioning

confidence: 99%

Winter survival of North American grassland birds is driven by weather and grassland condition in the Chihuahuan Desert

et al. 2017

View full text Add to dashboard Cite

Populations of grassland birds that overwinter in the Chihuahuan Desert are declining more rapidly than other grassland birds, and survival during the non‐breeding season may have a strong influence on population trends of these species. Habitat loss and deterioration due to desertification may be contributing to these declines, and the winter ecology of grassland birds under these changing environmental conditions remains relatively unexplored. To fill this information gap, we estimated the survival of two grassland‐obligate sparrows, Baird's Sparrows (Ammodramus bairdii) and Grasshopper Sparrows (A. savannarum), on their wintering grounds in the Chihuahuan Desert, and investigated the role of habitat structure and weather on survival rates. We deployed radio‐transmitters on Baird's (N = 49) and Grasshopper (N = 126) sparrows near Janos, Chihuahua, and tracked birds from November to March during the winters of 2012–2013 and 2013–2014. Causes of mortality included avian predators, mammals, and possibly weather. We estimated an overall weekly winter survival probability of ŝ = 92.73% (95% CI[s] = 88.63–95.44%) for Baird's Sparrows in 2012–2013. We estimated a weekly winter survival probability of ŝ = 93.48% (95% CI[s] = 90.29–96.67%) and ŝ = 98.78% (95% CI[s] = 97.88–99.68%) for Grasshopper Sparrow in 2012–2013 and 2013–2014, respectively. Weekly winter survival was lower with colder daily minimum temperatures for both species and in areas with taller shrubs for Grasshopper Sparrows, with the shrubs potentially increasing predation risk by providing perches for Loggerhead Shrikes (Lanius ludovicianus). Our results highlight the need to maintain healthy grass structure in wintering areas to provide birds with food, protection from predators, and adequate cover from inclement weather. Our results also demonstrate that the presence of shrubs can lower winter survival, and suggest that shrub encroachment into the winter habitat of these sparrows may be an important driver of their population declines. Shrub removal could increase survival of wintering sparrows in the Chihuahuan Desert by reducing availability of perches for avian predators, thus reducing predation risk.

show abstract

“…Variables used to estimate Colinus virginianus space use were related to the configuration and structure of vegetation on our study site. We chose to use vegetation (and associated landscape metrics described below) to model Colinus virginianus space use in relation to ambient temperature as this species is known to behaviorally modify their selection of vegetation during periods of thermal stress (Carroll et al, 2015a;Janke et al, 2015). An Iso Cluster Unsupervised classification method from 2-m-resolution satellite imagery was used to delineate vegetation.…”

Section: Space Use Analysismentioning

confidence: 99%

“…We compared overlap between four categories: the two thermal extreme categories (>35°C; À20 to À15°C), the category predicting the highest amount of space use (15-20°C), and the category containing the freezing point of water (0-5°C). We included the category containing the freezing point of water as Colinus virginianus have been shown to behaviorally respond to freezing weather events to increase fitness levels by adaptively selecting woody cover, which resulted in increased adult survival during these events (Janke et al, 2015). All pairwise comparisons of range overlap estimates across ambient temperature categories are presented in the supplementary material (Table S5).…”

Section: Space Use Analysismentioning

confidence: 99%

Extreme climatic events constrain space use and survival of a ground‐nesting bird

Tanner

Elmore

Fuhlendorf

et al. 2016

Global Change Biology

View full text Add to dashboard Cite

Two fundamental issues in ecology are understanding what influences the distribution and abundance of organisms through space and time. While it is well established that broad-scale patterns of abiotic and biotic conditions affect organisms' distributions and population fluctuations, discrete events may be important drivers of space use, survival, and persistence. These discrete extreme climatic events can constrain populations and space use at fine scales beyond that which is typically measured in ecological studies. Recently, a growing body of literature has identified thermal stress as a potential mechanism in determining space use and survival. We sought to determine how ambient temperature at fine temporal scales affected survival and space use for a ground-nesting quail species (Colinus virginianus; northern bobwhite). We modeled space use across an ambient temperature gradient (ranging from À20 to 38°C) through a MAXENT algorithm. We also used Andersen-Gill proportional hazard models to assess the influence of ambient temperature-related variables on survival through time. Estimated available useable space ranged from 18.6% to 57.1% of the landscape depending on ambient temperature. The lowest and highest ambient temperature categories (<À15°C and >35°C, respectively) were associated with the least amount of estimated useable space (18.6% and 24.6%, respectively). Range overlap analysis indicated dissimilarity in areas where Colinus virginianus were restricted during times of thermal extremes (range overlap = 0.38). This suggests that habitat under a given condition is not necessarily a habitat under alternative conditions. Further, we found survival was most influenced by weekly minimum ambient temperatures. Our results demonstrate that ecological constraints can occur along a thermal gradient and that understanding the effects of these discrete events and how they change over time may be more important to conservation of organisms than are average and broad-scale conditions as typically measured in ecological studies.

show abstract

Habitat influences Northern Bobwhite survival at fine spatiotemporal scales

Cited by 25 publications

References 65 publications

Broadcast supplemental feeding and northern bobwhite demographics in Texas

Broadcast supplemental feeding and northern bobwhite demographics in Texas

Winter survival of North American grassland birds is driven by weather and grassland condition in the Chihuahuan Desert

Extreme climatic events constrain space use and survival of a ground‐nesting bird

Contact Info

Product

Resources

About