Impacts of alternative grassland management regimes on the population ecology of grassland birds

We investigated the impacts of rangeland management practices on the diversity, density, and nest survival of grassland songbirds and on the demography, habitat selection, and population viability of Greater Prairie-Chickens (Tympanuchus cupido). Our study site was located in eastcentral Kansas and included portions of Chase, Greenwood, Lyon, and Morris Counties. We had access to ~1,100 km2 of private and public lands. Over 95% of the land was privately owned (~1040 km2), and the remaining ~5% was the Tallgrass Prairie National Preserve. Our final project report is based on data collected during a 3-year period from Feb. 2011 through Feb. 2014. Our study focused on grassland songbirds and Greater Prairie-Chickens as indicators of ecosystem response. Our analyses are based on direct comparisons between monitoring efforts in pastures managed with patch-burn grazing (PBG) and pastures managed with traditional intensive early stocking and annual burning (IESB).Citation: Sandercock, B.K., V.L. Winder, A.E. Erickson, and L.B. McNew. 2014. Impacts of alternative grassland management regimes on the population ecology of grassland birds. Kansas Department of Wildlife, Parks and Tourism, Final Project Report for Award No. KDWP-W-67-R. (technical report)

winTEr SUrvivOrShiP anD SiTE fiDEliTy Of nElSOn'S, SalTMarSh, anD SEaSiDE SParrOwS in nOrTh CarOlina

Abstract. Three species of coastal sparrows (Ammodramus nelsoni, nelson's Sparrow; A. caudacutus, Saltmarsh Sparrow; and A. maritimus, Seaside Sparrow) reside in north Carolina salt marshes in winter during their nonbreeding periods. we analyzed the timing of migration, survivorship, and site fidelity of these species with mark-recapture data from five winters (2006)(2007)(2008)(2009)(2010). By determining the percentage of individuals captured more than once, we documented a shift from transient to settled individuals during and following migration and used linear regressions to test whether this shift was related to mean monthly minimum temperatures. we also used MarK and capture histories over five winters to estimate probabilities of apparent survival and capture. On the basis of recapture data, the three species' populations were composed largely of transient individuals from October until the sparrows settled for the winter by late november. Our recapture data indicate that when coastal sparrows settle for the winter or return to the region in a subsequent year, they do so with high site fidelity. we found that the percent of nelson's and Seaside sparrows captured more than once had a negative relationship with mean monthly minimum temperature. we estimated survival of nelson's, Saltmarsh, and Seaside sparrows at 0.673, 0.520, and 0.483, respectively. Our data indicate that survival of these coastal sparrows through the nonbreeding season is comparable to existing estimates for their breeding populations. Surveys in the nonbreeding season and management plans should take into account the likely presence of a large proportion of transient individuals during migration. Resumen. Tres especies de gorrión, Ammodramus nelsoni, A. caudacutus y A. maritimus, residen en el invierno en las marismas de Carolina del norte, durante sus periodos no reproductivos. analizamos el momento de migración, la supervivencia y la fidelidad de sitio de estas especies con datos de captura-recaptura provenientes de cinco inviernos (2006)(2007)(2008)(2009)(2010). Mediante la determinación del porcentaje de individuos capturados más de una vez, documentamos un cambio de individuos transitorios a individuos establecidos durante y luego de la migración. luego, usamos regresiones lineales para evaluar si este cambio estuvo relacionado con las temperaturas mínimas medias mensuales. También usamos MarK e historias de captura a lo largo de cinco inviernos para estimar las probabilidades de supervivencia aparente y de captura. Sobre la base de los datos de recaptura, las poblaciones de las tres especies estuvieron compuestas principalmente por individuos transitorios desde octubre hasta que los gorriones se establecieron para pasar el invierno a finales de noviembre. nuestros datos de recaptura indicaron que cuando los gorriones de las especies estudiadas se establecen para pasar el invierno o regresan a la región en un año subsecuente, lo hacen exhibiendo una alta fidelidad de sitio. Encontramos que el porcentaje de individuos de A. nelsoni y A. maritimus capturados más de una vez tuvieron una relación negativa con la temperatura mínima media mensual. Estimamos la supervivencia de los individuos de A. nelsoni, A. caudacutus y A. maritimus en 0.673, 0.520 y 0.483, respectivamente. nuestros datos indican que la supervivencia de estas especies a lo largo de la estación no reproductiva es comparable con los estimados existentes para sus poblaciones reproductivas. los muestreos en la estación no reproductiva y los planes de manejo deberían considerar la presencia probable de una gran proporción de individuos transitorios durante la migración

Effects of wind energy development on survival of female greater prairie-chickens

The potential effects of wind energy development on wildlife have received increased attention over the past decade. In Kansas, optimal sites for wind energy development often overlap with preferred habitats of greater prairie-chickens Tympanuchus cupido. Our goal was to determine whether wind energy development affected survival of female prairie-chickens in a grassland ecosystem, assessing one potential impact of wind on an upland gamebird of conservation concern. We focused primarily on the response of female prairie-chickens to wind energy development because population dynamics of prairie-chickens are primarily determined by female demography. We monitored prairie-chickens at a wind facility in Kansas during a 2-year pre-construction (2007–2008) and a 3-year post-construction period (2009–2011). We used data from 220 radio-marked females to calculate weekly survival and hazard rates. We used cause of death for 81 mortality events to test for changes in the proportion of mortalities attributed to mammalian predators, avian predators and collisions. We observed an unexpected increase in annual survival during the post-construction period (0·57) compared with the pre-construction period (0·32). Distance from home range centroid to the nearest wind turbine site had no effect on weekly survival of females. Collision mortality events were rare, and most were associated with fences or transmission lines and not turbine blades. Most female mortality was due to predation (c. 90%). Differences in annual survival were driven by a higher risk of mortality during lekking activity in March and April during the pre-construction period (weekly hazard rate = 0·050–0·062) compared with the post-construction period (hazard rate = 0·012–0·021). We observed no change in the proportion of mortalities attributed to different causes between the two treatment periods. Synthesis and applications. Development of a wind energy facility had no negative effect on survival of female prairie-chickens. The results of our field study indicate that greater prairie-chickens are less sensitive to wind energy development than lesser prairie-chickens Tympanuchus pallidicinctus and greater sage-grouse Centrocercus urophasianus are to oil and gas development. We have strong evidence that survival increased after wind energy development, and hypothesize that energy development affected the local predator community, resulting in an indirect effect of decreased predation risk during the post-construction period

Mercury in Nelson's Sparrow Subspecies at Breeding Sites

Background: Mercury is a persistent, biomagnifying contaminant that can cause negative effects on ecosystems. Marshes are often areas of relatively high mercury methylation and bioaccumulation. Nelson’s Sparrows (Ammodramus nelsoni) use marsh habitats year-round and have been documented to exhibit tissue mercury concentrations that exceed negative effects thresholds. We sought to further characterize the potential risk of Nelson’s Sparrows to mercury exposure by sampling individuals from sites within the range of each of its subspecies

Factors affecting female space use in ten populations of prairie chickens

Conservation of wildlife depends on an understanding of the interactions between animal movements and key landscape factors. Habitat requirements of wide-ranging species often vary spatially, but quantitative assessment of variation among replicated studies at multiple sites is rare. We investigated patterns of space use for 10 populations of two closely related species of prairie grouse: Greater Prairie-Chickens (Tympanuchus cupido) and Lesser Prairie-Chickens (T. pallidicinctus). Prairie chickens require large, intact tracts of native grasslands, and are umbrella species for conservation of prairie ecosystems in North America. We used resource utilization functions to investigate space use by female prairie chickens during the 6-month breeding season from March through August in relation to lek sites, habitat conditions, and anthropogenic development. Our analysis included data from 382 radio-marked individuals across a major portion of the extant range. Our project is a unique opportunity to study comparative space use of prairie chickens, and we employed standardized methods that facilitated direct comparisons across an ecological gradient of study sites. Median home range size of females varied ~10-fold across 10 sites (3.6–36.7 km²), and home ranges tended to be larger at sites with higher annual precipitation. Proximity to lek sites was a strong and consistent predictor of space use for female prairie chickens at all 10 sites. The relative importance of other predictors of space use varied among sites, indicating that generalized habitat management guidelines may not be appropriate for these two species. Prairie chickens actively selected for prairie habitats, even at sites where ~90% of the land cover within the study area was prairie. A majority of the females monitored in our study (>95%) had activity centers within 5 km of leks, suggesting that conservation efforts can be effectively concentrated near active lek sites. Our data on female space use suggest that lek surveys of male prairie chickens can indirectly assess habitat suitability for females during the breeding season. Lek monitoring and surveys for new leks provide information on population trends, but can also guide management actions aimed at improving nesting and brood-rearing habitats

Characterization of mercury and its risk in Nelson's, Saltmarsh, and Seaside Sparrows.

BACKGROUND: Nelson's, Saltmarsh, and Seaside Sparrows (Ammodramus nelsoni, A. caudacutus, and A. maritimus, respectively) depend on marsh and wetland habitats--ecosystems in which mercury (Hg) bioavailability is notoriously high. The purpose of the present study was to address the potential impact of Hg on these species using first primary and breast feathers as non-destructive biomonitoring tools. METHODS AND PRINCIPAL FINDINGS: Feathers were sampled from wintering sparrows in North Carolina salt marshes (2006-2010). Feather Hg data were used in three risk analysis components (1) Threshold Component--examined feather Hg with regard to published negative effects thresholds; (2) Hg Dynamics Component--examined Hg in sparrows captured multiple times; and (3) Capture Frequency and Survival Component--tested for links between Hg and return frequency and survival. Threshold Component analyses indicated that Hg concentrations in 42-77% of sampled individuals (breast feather n = 879; first primary feather n = 663) were within the range associated with decreased reproduction in other avian species. Hg Dynamics Component analyses demonstrated that Hg increased between first and second captures for Nelson's (n = 9) and Seaside Sparrows (n = 23). Capture Frequency and Survival Component analyses detected a negative relationship between Hg and capture frequency in Nelson's Sparrows (n = 315). However, MARK models detected no effect of Hg on apparent survival in any species. CONCLUSION AND SIGNIFICANCE: This study indicates that current Hg exposure places a considerable proportion of each population at risk. In particular, 52% of all sampled Saltmarsh Sparrows exhibited first primary feather Hg concentrations exceeding those associated with a >60% reduction in reproductive success in other species. This study reports evidence for net annual bioaccumulation, indicating an increased risk in older individuals. These data can be used to inform future population assessments and management for these species

Associations between percent change in first primary feather Hg concentrations between first and second captures (in separate years) and first primary feather Hg at first capture.

<p>Linear regression analyses were not applied to these data; lines are for graphical display only.</p

ΔQAIC_c rankings for models used to test for the effect of breast feather mercury (Hg) on apparent survival in three species of coastal sparrows in NC salt marshes over five winters.

<p>Model notation follows White and Burnham (1999); (_·) indicates that a given parameter estimate did not vary among species or years; ΔQAIC_c indicates quasi-Akaike’s information criterion simple differences adjusted for small sample size and a <i>ĉ</i> (variance inflation factor) adjustment of 2.107; <i>w_i</i> indicates Akaike’s model weight; <i>k</i> indicates the number of parameters included in a given model. Years refers to the time intervals (between consecutive banding years) for which MARK generates parameter estimates; survival refers to apparent survival; capture refers to capture probability. Models with non-informative parameters were removed from consideration as candidate models and are not shown here.</p

Associations between breast feather Hg at first and second captures (in separate years) for Nelson’s (A) and Seaside Sparrows (B).

<p>Linear regression analyses were not applied to these data; lines are for graphical display only.</p

Model averaged estimates of apparent survival and accompanying unconditional standard errors for coastal sparrows captured during five winters (2006–2010) in NC salt marshes.

<p>Model-averaged estimates were calculated based on model weights when all 27 candidate models were present in the model set.</p>a<p>Refers to year i in survival interval from i to i +1 (e.g. 2006 = interval from 2006 to 2007).</p