Direct Effects of Cattle on Grassland Birds in Canada

Bleho, Barbara I.; Koper, Nicola; Machtans, Craig S.

doi:10.1111/cobi.12259

Cited by 36 publications

(25 citation statements)

References 49 publications

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“…Although benefits to breeding grassland birds have been suggested (McGauley 2004, OMAFRA 2012, empirical evidence of the effects of rotational grazing on Bobolink breeding success is limited. Bleho et al (2014) found that the risk of nest destruction from cattle was similar between continuous and rotational grazing for songbirds, ducks, and shorebirds in Canada. However, rotational grazing may provide management opportunities that benefit breeding grassland birds because cattle grazing is spatially and temporally controlled across paddocks.…”

Section: Introductionmentioning

confidence: 97%

“…Cattle can negatively affect nests by removing vegetation that provides cover for nests (potentially increasing predation) and by trampling (i.e., stepping or lying down on nests; Temple et al 1999, Renfrew et al 2005, Perlut and Strong 2011, MacDonald and Nol 2017. The proportion of nests affected by cattle is based on a combination of stocking density (i.e., the number of cattle per unit area) and the number of days a paddock is grazed (i.e., stocking rate, calculated as: number of cattle × days grazed/area grazed; Jensen et al 1990, Paine et al 1996, Bleho et al 2014, MacDonald and Nol 2017. In North Dakota, Kerns et al (2010) found that rotational grazing by cattle was not associated with Bobolink nest survival; 1 of 91 nests was trampled under typical stocking rates for the region.…”

Section: Introductionmentioning

confidence: 99%

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Rotational grazing of beef cattle to support Bobolink breeding success

Campomizzi¹,

Lebrun‐Southcott²,

Vliet³

et al. 2019

ACE

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Conservation actions for the federally and provincially threatened Bobolink (Dolichonyx oryzivorus) in Ontario, Canada are ongoing in agricultural landscapes, including pastures. However, conditions conducive to Bobolink fledging young from breeding territories in rotationally grazed beef cattle (Bos taurus) pastures are not well understood. We tested two management strategies designed to provide habitat where Bobolink could fledge young in rotationally grazed pastures. We conducted (1) a refuge paddock experiment using a crossover design, comparing fledging success when paddocks were ungrazed in one year to when they were grazed in another year; and (2) a light spring grazing experiment. Additionally, we explored associations between fledging of young from territories with cattle stocking rate and date that cattle first entered paddocks. We used spot mapping and nest monitoring to determine if young fledged in 83 Bobolink territories in 2016 and 72 territories in 2017 on six farms in the Ottawa Valley, Ontario. In the refuge paddock experiment, 54% (N = 28) of Bobolink territories fledged young in eight ungrazed paddocks compared to 16% (N = 25) when these paddocks were grazed in another breeding season. In the light spring grazing experiment, 67% (N = 12) of territories fledged young from four paddocks that were grazed with a low stocking rate between 21 May and 03 June 2017 and not again until after 02 July. Additionally, predictions from a logistic regression model indicated that the probability of young fledging from a territory (N = 118) decreased from 0.53 to 0.04 when mid-season stocking rates increased from 0 to 174 cattle-days/ha. Our results illustrate that paddocks on rotationally grazed beef cattle farms that are ungrazed until the Bobolink breeding season is finished or grazed lightly for a brief duration soon after territories are established can provide areas that enable Bobolink to fledge young. Rotation des pâturages de b!ufs pour soutenir le succès de nidification du Goglu des prés RÉSUMÉ. Des activités de conservation visant le Goglu des prés (Dolichonyx oryzivorus), espèce menacée au niveaux fédéral et provincial en Ontario, Canada, ont cours dans les paysages agricoles, y compris les pâturages. Toutefois, on ne comprend pas bien les conditions qui favorisent l'envol des jeunes goglus de territoires de nidification situés dans des pâturages de b!ufs (Bos taurus) sous rotation. Nous avons testé deux stratégies de gestion visant à fournir de l'habitat dans lequel les goglus pouvaient mener leurs jeunes à l'envol dans des pâturages sous rotation. Nous avons effectué (1) une expérience d'enclos-refuge au moyen d'un plan d'étude croisé, comparant le succès de jeunes à l'envol lorsque des enclos ne servaient pas de pâturage une année à celui lorsque les enclos servaient de pâturage une autre année; et (2) une expérience de pâturage printanier léger. De plus, nous avons exploré les relations entre l'envol de jeunes et la densité de bétail, et la date à laquelle le bétail entrait dans l'enclos. Nous ...

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Section: Introductionmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

Rotational grazing of beef cattle to support Bobolink breeding success

Campomizzi¹,

Lebrun‐Southcott²,

Vliet³

et al. 2019

ACE

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“…High stocking densities on lowland grasslands also cause direct mortality of birds due to increased trampling of egg clutches and broods in nests (Vickery et al, 2001) although there is doubt whether similar effects are caused by free-range grazing herbivores, at lower stocking densities, in sub-montane ecosystems. It appears that grazers also have indirect effects on bird populations via a reduction in the availability of vegetation structures suitable for nest construction and concealment from predators, rather than direct mortality through nest trampling (Bleho et al, 2014).…”

Section: Introductionmentioning

confidence: 99%

The response of spider (Araneae) assemblages to structural heterogeneity and prey abundance in sub-montane vegetation modified by conservation grazing

Dennis

Skartveit

Kunaver

et al. 2015

Global Ecology and Conservation

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Submitted on 29 August 2014; MS #GECCO-D-14-00081R1; accepted for publication, 19 March 2015; Proofs checked and returned.The effect of experimental livestock grazing regimens (4 treatments x 6 replicates) on spiders via habitat structure and prey abundance was investigated on sub-montane habitats in the Southern Highlands of Scotland. The study, 2002-04 included a baseline survey under the prior, commercial sheep grazing regimen and two assessments of spider assemblages post-treatment: commercial stocking density of sheep; 1/3 stocking density with sheep; 1/3 stocking density cattle with sheep; and no grazing. Spiders were sampled with a suction sampler, five sucks at each of 25 sample units by 24 plots (600 samples in 2003 and 2004, ca. 300 in 2002). Spider abundance and species richness increased under reduced stocking density, mixed herbivore and ungrazed treatments indirectly via changes in vegetation structure and prey abundance. The results refuted a meta-analysis that concluded species richness of spiders is unaffected by grazing. Grazing regimens caused turnover in species composition more than the net difference in species richness suggested, implying that no single, optimal grazing regimen will support as many species as a patchwork under varied grazing management. Conservation grazing benefits spiders and will have significant benefits for food webs in sub-montane ecosystems but the period to equilibrium after changes to grazing requires further investigation.publishersversionPeer reviewe

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“…Other studies have found small direct effects of nest destruction by cattle, but these effects were deemed unimportant in Canada (e.g. Bleho et al 2014). Simulations, as applied here, allowed us to directly assess projected population-level effects to fully understand relative implications of management.…”

Section: Discussionmentioning

confidence: 97%

Risk from cattle trampling to nests of an endangered passerine evaluated using artificial nest experiments and simulations

Rolek¹,

Schrott²,

Poulton³

et al. 2016

ACE

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Grasslands are often grazed by cattle and many grassland birds nest on the ground, potentially exposing nests to trampling. We tested for trampling risk introduced by cattle to nests of endangered Florida Grasshopper Sparrows (Ammodramus savannarum floridanus) using experimentally paired grids of artificial nests (i.e., clay targets) similar in size to nests of Florida Grasshopper Sparrows and counted the number of clay targets that were broken in paired grazed and ungrazed enclosures. Clay targets in grazed grids were trampled 3.9% more often than their respective ungrazed grids, and measurements of cattle presence or density were correlated with the number of broken clay targets, suggesting that excluding cattle during breeding is an important management recommendation for the Florida Grasshopper Sparrow. Trampling rates within grazed enclosures were spatially homogeneous with respect to cattle infrastructure such as supplemental feeding troughs and fences, and forests and stocking density were poor predictors of trampling rates when excluding ungrazed grids. We used population viability analysis to compare quasi-extinction rates, intrinsic growth rates, and median abundance in grazed and ungrazed Florida Grasshopper Sparrow aggregations to further understand the biological significance of management aimed at reducing trampling rates during the breeding season. Simulations indicated that trampling from grazing increased quasi-extinction rates by 41% while reducing intrinsic growth rates by 0.048, and reducing median abundance by an average of 214 singing males after 50 years. Management should avoid grazing enclosures occupied by Florida Grasshopper Sparrows during the nesting season to minimize trampling rates. Our methods that combine trampling experiments with population viability analysis provide a framework for testing effects from trampling on other grassland ground-nesting birds, and can directly inform conservation and management of the Florida Grasshopper Sparrow. Évaluation du risque de piétinement par le bétail de nids de passereaux menacés à partir d'expériences avec des nids artificiels et de simulations RÉSUMÉ. Les prairies sont souvent broutées par le bétail et de nombreux oiseaux de prairie nichent au sol, exposant ainsi potentiellement leur nid au piétinement. Nous avons testé le risque de piétinement causé par le bétail des nids du Bruant sauterelle de Floride (Ammodramus savannarum floridanus), une espèce menacée, au moyen de grilles expérimentales appariées de nids artificiels (c.à-d. disques d'argile), semblables en taille aux nids des Bruants sauterelles de Floride. Nous avons compté le nombre de disques d'argile qui ont été détruits dans les enclos appariés broutés ou non broutés. Les disques d'argile situés dans les grilles broutées ont été piétinés 3,9 % plus souvent que ceux qui sont sis dans les grilles non broutées appariées, et les mesures de la présence du bétail ou de la densité étaient corrélées avec le nombre de disques détruits; ces résultats nous mènent à recommander fortement...

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Direct Effects of Cattle on Grassland Birds in Canada

Cited by 36 publications

References 49 publications

Rotational grazing of beef cattle to support Bobolink breeding success

Rotational grazing of beef cattle to support Bobolink breeding success

The response of spider (Araneae) assemblages to structural heterogeneity and prey abundance in sub-montane vegetation modified by conservation grazing

Risk from cattle trampling to nests of an endangered passerine evaluated using artificial nest experiments and simulations

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