Forb Standing Crop Response to Grazing and Precipitation

Fulbright, Timothy E.; Drabek, Dillan J.; Ortega-S., J. Alfonso; Hines, Stacy L.; Saenz, Ramon; Campbell, Tyler A.; Hewitt, David G.; Wester, David B.

doi:10.1016/j.rama.2021.08.007

Cited by 9 publications

(22 citation statements)

References 51 publications

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“…The vegetation community is a mosaic of Tamaulipan thornscrub, live oak forests ( Quercus virginiana ), and open grasslands (Moczygemba et al . 2012; Foley et al . 2017).…”

Section: Methodsmentioning

confidence: 99%

“…These included studies conducted in 2006–2008 (Moczygemba et al . 2012), 2015–2016 (Foley et al . 2017), and 2019–2020 (Sliwa 2021).…”

Section: Methodsmentioning

confidence: 99%

“…2012). Nilgai captured during 2015–2016 (Foley et al . 2017) were captured in April and fitted with GPS radio-collars (Lotek Wireless Inc., Newmarket, Ontario, Canada) that recorded locations at either 1-h or 13-h intervals.…”

Section: Methodsmentioning

confidence: 99%

“…Foley et al . (2017), suggest that patterns of space use by nilgai are dependent on a complex social system and appear to fluctuate seasonally. Owing to our limited knowledge of nilgai ecology, we felt making assumptions of pre-capture behaviour would be imprudent.…”

Section: Methodsmentioning

confidence: 99%

“…Nilgai are large animals (adult males, x̄ = 241 kg) and do not respond to feed or bait (Leslie 2008); the most common capture method on North American rangelands is the helicopter and net gun (Moczygemba et al . 2012; Foley et al . 2017).…”

Section: Introductionmentioning

confidence: 99%

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Effects of helicopter net gunning on the survival and movement behaviour of nilgai antelope

et al. 2023

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Context. Research on large, terrestrial mammals often requires physical captures to attach tags or collars, collect morphological data, and collect biological samples. Choice of capture method should minimise pain and distress to the animal, minimise risk to personnel, and consider whether the method can achieve study objectives without biasing results. Aims. We studied how capture via helicopter net-gunning affected survival, post-capture movement patterns, and space use of exotic nilgai (Boselaphus tragocamelus) in southern Texas, USA. Methods. We estimated daily survival rates for 101 collared nilgai over 28 days, following 125 captures. We calculated mean daily movement rates and net-squared displacement for 21 recaptured nilgai for 60 days, starting 30 days before capture. Key results. The survival probability of 125 nilgai individuals was 0.97 (95% CI = 0.92-0.99) over the 28 days following capture, with the lowest daily survival for the day after capture (x ¯ = 0.99; 95% CI = 0.96-1.00). We observed an increase of ~65% in the mean daily movement rate of 134 m/h on the first 2 days since capture, followed by a period of reduced movement out to the 5th day before returning to pre-capture levels. Analysis of netsquared displacement for 21 nilgai showed that 17 resumed pre-capture space-use patterns within a week, whereas four individuals did not return to the pre-capture range for ≥1 month. Conclusions. Capture-related mortality rates for nilgai using helicopter net-gunning in our study (3%) were similar or lower than those reported for similar species captured using the same method. While we were able to detect a period of elevated movement rates, followed by a recovery period of diminished movement as a result of capture, nilgai appeared to return to typical behaviour ~6 days post-capture. Most nilgai in our study also resumed typical space-use patterns within a week of capture; however, our results suggest high individual variability in their response. Implications. We recommend using net-gunning from a helicopter as a method for capturing nilgai when conditions and where vegetation and topography allow. We suggest censoring data for a minimum of 7 days following capture for analyses related to survival and movement rates. For analyses relating to space use, we suggest inspecting net-squared displacement or some similar displacement analysis for each animal separately to account for individual variation in response and exclude data accordingly.

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“…The vegetation community is a mosaic of Tamaulipan thornscrub, live oak forests ( Quercus virginiana ), and open grasslands (Moczygemba et al . 2012; Foley et al . 2017).…”

Section: Methodsmentioning

confidence: 99%

“…These included studies conducted in 2006–2008 (Moczygemba et al . 2012), 2015–2016 (Foley et al . 2017), and 2019–2020 (Sliwa 2021).…”

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Effects of helicopter net gunning on the survival and movement behaviour of nilgai antelope

et al. 2023

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Relationships between plant species richness and grazing intensity in a semiarid ecosystem

Fulbright,

Ortega‐Santos,

Hines

et al. 2023

Ecology and Evolution

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Plant species richness is an important property of ecosystems that is altered by grazing. In a semiarid environment, we tested the hypotheses that (1) small‐scale herbaceous plant species richness declines linearly with increasing grazing intensity by large ungulates, (2) precipitation and percent sand interact with grazing intensity, and (3) response of herbaceous plant species richness to increasing intensity of ungulate grazing varies with patch productivity. During January–March 2012, we randomly allocated 50, 1.5‐m × 1.5‐m grazing exclosures within each of six 2500 ha study sites across South Texas, USA. We counted the number of herbaceous plant species and harvested vegetation in 0.25‐m2 plots within exclosures (ungrazed control plots) and in the grazed area outside the exclosures (grazed treatment plots) during October–November 2012–2019. We estimated percent use (grazing intensity) based on the difference in herbaceous plant standing crop between control plots and treatment plots. We selected the negative binomial regression model that best explained the relationship between grazing intensity and herbaceous plant species richness using the Schwarz‐Bayesian information criterion. After accounting for the positive effect of precipitation and percent sand on herbaceous plant species richness, species richness/0.25 m2 increased slightly from 0% to 30% grazing intensity and then declined with increasing grazing intensity. Linear and quadratic responses of herbaceous plant species richness to increasing grazing intensity were greater for the least productive patches (<15.7 g/0.25 m2) than for productive patches (≥15.7 g/0.25 m2). Our results followed the pattern predicted by the intermediate disturbance hypothesis model for the effect of grazing intensity on small‐scale herbaceous plant species richness.

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Understanding an ecological tug of war: Disentangling competition between native and domesticated ungulates

Spencer,

DeYoung,

Foley

et al. 2024

Ecosphere

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Competition is a complex ecological process involving individual and community interactions at ecological and evolutionary time scales. Individuals within and between species can compete through two mechanisms: exploitative and interference competition. These mechanisms often co‐occur, making it difficult to develop a mechanistic understanding of competition. We used movement data from 19 GPS‐collared white‐tailed deer (Odocoileus virginianus) associated with an experimental cattle (Bos taurus) stocking event to disentangle exploitative from interference competition between deer and cattle. We assumed any effect of exploitative competition on reduced forage availability for deer would not occur immediately, whereas interference competition would occur immediately after cattle stocking, and antagonistic interactions between deer and cattle would alter deer behavior and degrade habitat quality. We evaluated the effects of the experimental stocking event on deer for 30‐day intervals before and after the cattle stocking event as this period was assumed to be too short for cattle to reduce deer forage resources through exploitative competition. We assessed the effects of interference competition using the movement metrics of home range size, speed, and resource selection. We used home range size as a proxy for habitat quality, assuming cattle would degrade deer habitat through means other than loss of forage. We used speed and resource selection as indicators of deer behavior. We experimentally stocked cattle at densities ranging from 0 to 15.7 animal units/km2 to previously destocked pastures. Stocking densities did not influence home range sizes ( = 17.033, 85% CI: −189.471 to 235.322) of deer. However, as stocking density increased, deer decreased speed ( = −0.014, 85% CI: −0.020 to −0.008) and increased selection for woody cover ( = 0.047, 85% CI: 0.031 to 0.063) and sandier soils ( = 0.062, 85% CI: 0.033 to 0.090). Our results suggest cattle density altered deer behavior and their realized niche within our system. Our results demonstrated mechanisms by which competition with livestock could influence native wildlife populations, which can be used to inform management of multiuse working landscapes.

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Forb Standing Crop Response to Grazing and Precipitation

Cited by 9 publications

References 51 publications

Effects of helicopter net gunning on the survival and movement behaviour of nilgai antelope

Effects of helicopter net gunning on the survival and movement behaviour of nilgai antelope

Relationships between plant species richness and grazing intensity in a semiarid ecosystem

Understanding an ecological tug of war: Disentangling competition between native and domesticated ungulates

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