Restoration of Grasslands and Nesting Success of Dickcissels (<i>Spiza americana</i>)

Lituma, Christopher M.; Morrison, Michael L.; Whiteside, Jay D.

doi:10.1894/0038-4909-57.2.138

Cited by 7 publications

(5 citation statements)

References 52 publications

(64 reference statements)

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“…Importance of structure for dickcissels also is supported in previous studies that observed similar densities of this species in cool-and warm-season grass fields (Jacobs et al, 2012;Jaster et al, 2014), whereas dickcissels responded positively to tall fescue-dominated pastures when livestock management increased biomass of native warm-season grasses (Johnson and Sandercock, 2010). Densities of dickcissels also did not differ significantly between grazed bermudagrass and restored native grass pastures in Blackland Prairie of Texas (Lituma et al, 2012).…”

Section: Widespread Establishment Of Exotic Forages For Beef Productimentioning

confidence: 90%

Converting exotic forages to native warm-season grass can increase avian productivity in beef production systems

Monroe

Chandler

Burger

et al. 2016

Agriculture, Ecosystems & Environment

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Grasslands are among the most imperiled ecosystems in the world, and establishment of exotic forage grasses and management for uniform utilization may have contributed to population declines of many obligate grassland bird species in North America. Native warm-season grasses (NWSG) are increasingly promoted as viable alternatives to exotic forages currently in production such as bermudagrass (Cynodon dactylon) and tall fescue (Schedonorus arundinacea), but structure of native bunchgrasses also may offer nesting habitat for birds such as the dickcissel (Spiza americana). Establishing NWSG pastures may thereby create an opportunity for land-sharing, where agriculture incorporates biodiversity-friendly practices. We investigated dickcissel responses to NWSG and grazing at the Prairie Research Unit in Monroe Co., Mississippi (USA), where we established a gradient of management intensity among four treatments in small, operational-scale pastures (6.4−10.5 ha). Treatments included grazed exotic forages, two grazed NWSG treatments including Indian grass (Sorghastrum nutans) monoculture and grazed mixed NWSG polyculture of Indian grass, little bluestem (Schizachyrium scoparium), and big bluestem (Andropogon gerardii), and a non-grazed NWSG polyculture treatment. We applied a multi-state capture-recapture model in a Bayesian framework to estimate dickcissel nest density and productivity while accounting for nest stage-specific variation in survival and detection. Nest density and productivity were consistently greater in non-grazed NWSG than grazed exotic pasture, whereas grazed NWSG productivity was intermediate but declined between years. We also found that variation in survival and density did not always correspond with estimated productivity, and thus solely relying on either parameter may be misleading when making inferences on habitat quality. These results suggest a positive response to NWSG among dickcissels in this system, but grazing may reduce nest site availability, and 3 consequently productivity. Native warm-season forages may be a viable land-sharing alternative by increasing productivity of tall structure specialists such as dickcissels compared with exotic grass pastures currently in production, but grazing should be managed to ensure availability of tall vegetation structure for nest sites.

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Section: Widespread Establishment Of Exotic Forages For Beef Productimentioning

confidence: 90%

Converting exotic forages to native warm-season grass can increase avian productivity in beef production systems

Monroe

Chandler

Burger

et al. 2016

Agriculture, Ecosystems & Environment

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“…To minimize ambiguity, we modeled survival over the “nesting period” which could include incubation for precocial birds and incubation plus laying for altricial birds. We modeled a 28‐day nesting period to cover the range of incubation and laying periods for multiple species (Conover, Dinsmore, & Burger, ; Lituma, Morrison, & Whiteside, ; Williams, Austin, & Peoples, ). For each nest survival analysis, we simulated 600 nests over the study period with an intercept (β 0 ) corresponding to a mean nest success rate 35% for a 28‐day nesting period, before incorporating effects of ACH.…”

Section: Methodsmentioning

confidence: 99%

Timing of nest vegetation measurement may obscure adaptive significance of nest‐site characteristics: A simulation study

McConnell

Monroe

Burger

et al. 2017

Ecology and Evolution

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Advances in understanding avian nesting ecology are hindered by a prevalent lack of agreement between nest‐site characteristics and fitness metrics such as nest success. We posit this is a result of inconsistent and improper timing of nest‐site vegetation measurements. Therefore, we evaluated how the timing of nest vegetation measurement influences the estimated effects of vegetation structure on nest survival. We simulated phenological changes in nest‐site vegetation growth over a typical nesting season and modeled how the timing of measuring that vegetation, relative to nest fate, creates bias in conclusions regarding its influence on nest survival. We modeled the bias associated with four methods of measuring nest‐site vegetation: Method 1—measuring at nest initiation, Method 2—measuring at nest termination regardless of fate, Method 3—measuring at nest termination for successful nests and at estimated completion for unsuccessful nests, and Method 4—measuring at nest termination regardless of fate while also accounting for initiation date. We quantified and compared bias for each method for varying simulated effects, ranked models for each method using AIC, and calculated the proportion of simulations in which each model (measurement method) was selected as the best model. Our results indicate that the risk of drawing an erroneous or spurious conclusion was present in all methods but greater with Method 2 which is the most common method reported in the literature. Methods 1 and 3 were similarly less biased. Method 4 provided no additional value as bias was similar to Method 2 for all scenarios. While Method 1 is seldom practical to collect in the field, Method 3 is logistically practical and minimizes inherent bias. Implementation of Method 3 will facilitate estimating the effect of nest‐site vegetation on survival, in the least biased way, and allow reliable conclusions to be drawn.

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“…Indeed, the species we studied have different habitat requirements and are associated with grasslands in varying stages of succession and with varying degrees of disturbance. Furthermore, other workers have reported differences in bird occupancy, abundance, and nest survival associated with structural features of managed grasslands (Cunningham and Johnson 2006, Jacobs et al 2012, Lituma et al 2012, Irvin et al 2013.…”

Section: Discussionmentioning

confidence: 99%

“…In Missouri, restored CRP grasslands acted as an ecological source for eastern meadowlark, field sparrow, and grasshopper sparrow but were ecological traps for red‐winged blackbirds and dickcissels (McCoy et al ). Similarly, in Texas, restored NWSG fields may have been acting as ecological traps for dickcissels, when compared with non‐native bermudagrass ( Cynodon dactylon ) pastures (Lituma et al ). Additional research is needed to evaluate grassland bird demographics when the grass is being managed for production objectives and how those contributions are affected by landscape context.…”

Section: Discussionmentioning

confidence: 99%

Grasslands bird occupancy of native warm‐season grass

et al. 2016

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Grassland birds have declined more than any other guild in the United States because of loss and degradation of native grasslands. The United States Department of Agriculture Farm Bill programs have restored some native warm‐season grasses (NWSG), but populations of many grassland bird species continue to decline. Market‐based NWSG uses focused on hay, pasture, and biofuel feedstock may be more appealing to landowners, and may still provide grassland bird habitat on the landscape. We examined breeding grassland bird occupancy of 102 NWSG production fields including 5 treatments (control [n = 37], grazing [n = 7], hay [n = 22], seed [n = 21], and biofuel [n = 15] production) in Kentucky and Tennessee during 2009–2010 breeding seasons. We used a robust design model in Program MARK to determine occupancy and detection rates for grassland birds. We modeled occupancy differences among treatments and sites (i.e., KY, TN), and included covariates (i.e., field‐level vegetation metrics and landscape composition at 3 scales [250 m, 500 m, and 1 km]) for eastern meadowlark (Sturnella magna), field sparrow (Spizella pusilla), grasshopper sparrow (Ammodramus savannarum), northern bobwhite (Colinus virginianus), and red‐winged blackbird (Agelaius phoeniceus). Covariates that influenced occupancy included treatment (field sparrow, 2009 only), site (eastern meadowlark, grasshopper sparrow, and northern bobwhite), percent NWSG cover (positive, red‐winged blackbird), and percent forest cover within 250 m (negative for eastern meadowlark, grasshopper sparrow, northern bobwhite, and red‐winged blackbird) or within 1 km (negative, field sparrow). Our results suggest that forest cover in the surrounding landscape negatively influences species occupancy, and species occupancy generally did not differ among NWSG production treatments. These treatments could be an alternative means to provide grassland bird habitat within an agriculture production landscape. © 2016 The Wildlife Society.

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Restoration of Grasslands and Nesting Success of Dickcissels (Spiza americana)

Cited by 7 publications

References 52 publications

Converting exotic forages to native warm-season grass can increase avian productivity in beef production systems

Converting exotic forages to native warm-season grass can increase avian productivity in beef production systems

Timing of nest vegetation measurement may obscure adaptive significance of nest‐site characteristics: A simulation study

Grasslands bird occupancy of native warm‐season grass

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