Habitat Associations of Migrating and Overwintering Grassland Birds in Southern Texas

Igl, Lawrence D.; Ballard, Bart M.

doi:10.2307/1370064

Cited by 43 publications

(39 citation statements)

References 20 publications

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“…This pattern has been well documented for grassland birds (Coppedge et al 2001;Cunningham and Johnson 2006;Winter et al 2006;Block and Morrison 2010), but has also been observed for mammals (Krogh et al 2002;Blaum et al 2007a) and reptiles (Mendelson and Jennings 1992;Pike et al 2011). When woody cover exceeds species-specific thresholds, which as yet have been poorly established, populations of grassland-associated species are displaced (Grant et al 2004;Sirami et al 2009) and animal communities shift from being dominated by grassland-associated species to shrubland-associated species (Igl and Ballard 1999;Rosenstock and Van Riper 2001;Skowno and Bond 2003;Sirami and Monadjem 2012). Overall, richness of animal communities is likely maximized where cover of woody plants is below the threshold levels that displace grassland specialists but above levels where habitat becomes more exclusively suitable for shrub-associated species (Fig.…”

Section: Animalsmentioning

confidence: 71%

Woody Plant Encroachment: Causes and Consequences

Archer

Andersen

Predick

et al. 2017

Springer Series on Environmental Management

384

379

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Woody vegetation in grasslands and savannas has increased worldwide over the past 100-200 years. This phenomenon of "woody plant encroachment" (WPE) has been documented to occur at different times but at comparable rates in rangelands of the Americas, Australia, and southern Africa. The objectives of this chapter are to review (1) the process of WPE and its causes, (2) consequences for ecosystem function and the provision of services, and (3) the effectiveness of management interventions aimed at reducing woody cover. Explanations for WPE require consideration of multiple interacting drivers and constraints and their variation through time at a given site. Mean annual precipitation sets an upper limit to woody plant cover, but local patterns of disturbance (fire, browsing) and soil properties (texture, depth) prevent the realization of this potential. In the absence of these constraints, seasonality, interannual variation, and intensity of precipitation events determine the rate and extent of woody plant expansion. Although probably not a triggering factor, rising atmospheric CO 2 levels may have favored C 3 woody plant growth. WPE coincided with the global intensification of livestock grazing that by reducing fine fuels, hence fire frequency and intensity, facilitated WPE. From a conservation perspective, WPE threatens the maintenance of grassland and savanna

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Section: Animalsmentioning

confidence: 71%

Woody Plant Encroachment: Causes and Consequences

Archer

Andersen

Predick

et al. 2017

Springer Series on Environmental Management

384

379

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“…Transects were randomly placed within patches using ArcGIS 10.0 (ESRI 2011) but constrained so that transects were .150 m apart and .100 m from patch edges to ensure independence between sites and prevent any double counting. Sampling was conducted during daylight hours by one observer on days with winds less than 20 km/h and no precipitation (Igl and Ballard 1999). Surveys were conducted four v www.esajournals.org times in 2011 and 2013 and three times in 2012.…”

Section: Data Collectionmentioning

confidence: 99%

“…Although the complexity of avian life cycles complicates conservation and management efforts, the extent and duration of seasonal movements by grassland birds emphasizes the need for information in areas other than the breeding grounds (Igl and Ballard 1999). Monitoring avian communities during winter is challenging.…”

Section: Introductionmentioning

confidence: 99%

“…The limited number of studies that have examined winter bird communities typically report habitat use in the absence of disturbance, or they examine the affects of fire and grazing independently (Igl and Ballard 1999, Gordon 2000, Baldwin et al 2007). Both of these scenarios are not commonly practiced in working grassland landscapes which makes application to conservation difficult.…”

Section: Introductionmentioning

confidence: 99%

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Structural heterogeneity increases diversity of non‐breeding grassland birds

2014

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Abstract. Grassland birds have experienced greater population declines than any other guild of birds inNorth America, and yet we know little about habitat use and the affects of management during their nonbreeding period on wintering grounds. The paucity of information on wintering grassland birds limits our ability to develop effective conservation strategies. We investigated habitat use by the winter bird community in grasslands with restored heterogeneity resulting from the interactive effects of fire and grazing. We used 500 m line transects distributed across patches (i.e., ,13, 13-24, and .24 months post disturbance) resulting from spring burning with growing season grazing (April-Sept) and quantified avian relative abundance, community structure, and probability of patch occupancy while accounting for imperfect detection. Grassland structure that resulted from the fire-grazing interaction created heterogeneity among patches that influenced avian habitat use during winter. Generalist birds such as the Savannah Sparrow (Passerculus sandwichensis) and meadowlarks (Sturnella spp.) were relatively common in all patch types while more specialized species such as the Smith's Longspur (Calcarius pictus) and Le Conte's Sparrow (Ammodramus leconteii ) reached greatest abundance and probability of occupancy in the patches with the least and greatest time post disturbance, respectively. This research provides novel information on the response of wintering birds to restored ecological processes in grasslands and can improve efforts to create effective conservation strategies. Our findings add to a growing body of literature supporting the use of fire and grazing to create a shifting grassland mosaic that increases vegetation structural and compositional heterogeneity and maximizes native biodiversity within rangeland ecosystems through the conservation of natural patterns and processes.

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“…Such emphasis on breeding season ecology occurs despite the fact that most grassland species are migratory and spend at least half the year in migration and on separate wintering grounds (Igl and Ballard 1999). As a result, it is still uncertain what role habitat loss or alteration on the wintering grounds of grassland birds may play in their recent decline.…”

Section: Introduction: Grassland Birds and Natural Resource Extractionmentioning

confidence: 99%

Impacts of Oil and Gas Development on Wintering Grassland Birds at Padre Island National Seashore, Texas

Lawson¹,

Morrison²,

Slack³

2011

Southeastern Naturalist

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, I surveyed 5 active, 4 abandoned, and 4 road sites to investigate the relationship between distance from disturbance (well pads, access roads) and bird abundance. I also compared abundance among the 3 site types. At each site I recorded bird numbers and species in 10-m distance bands along all transects (4 transects/well, 2 transects/road), each extending 300 m from the road or pad.At road sites bird abundance was positively correlated with increased distance from road edge, but I found no linear relationship at active or abandoned well sites.However, mean bird abundance in the first (0-30-m) distance interval of active well transects was less than half that at the second interval, and was the lowest value for all active intervals except the ninth. First-interval abundance at active wells was lower than abundance at any abandoned well interval. Road transects likewise showed low abundance in the initial interval, although unlike at active wells abundance increased steadily with distance from the center of disturbance.This trend of lower overall numbers at the first interval of active well transects was driven largely by 1 species, the meadowlark. A combination of high noise levels near active well pads (up to 80 dB) and lack of tall vegetation (on average 30% lower iv than the 60-90-m interval) from which to sing may have contributed to low numbers of meadowlarks, which were the only birds to sing regularly during my study period.While most birds appear to be minimally affected by resource extraction at Padre Island, to ensure minimal impacts on sensitive species I recommend: 1) reducing noise at active sites, 2) limiting disturbance to vegetation near pads and roads, 3) maintaining existing perch sites, 4) restoring all vegetation to its pre-extraction condition, 5) limiting road construction. v DEDICATIONTo my mother and father, for instilling in me a love of wild places of all kinds, and above all for imparting an irrepressible sense of curiosity about the world; And also to Briana, without whom it would have been an entirely different experience.vi

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Habitat Associations of Migrating and Overwintering Grassland Birds in Southern Texas

Cited by 43 publications

References 20 publications

Woody Plant Encroachment: Causes and Consequences

Woody Plant Encroachment: Causes and Consequences

Structural heterogeneity increases diversity of non‐breeding grassland birds

Impacts of Oil and Gas Development on Wintering Grassland Birds at Padre Island National Seashore, Texas

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