Increased searching and handling effort in tall swards lead to a Type IV functional response in small grazing herbivores
Understanding the functional response of species is important in comprehending the species’ population dynamics and the functioning of multi-species assemblages. A Type II functional response, where instantaneous intake rate increases asymptotically with sward biomass, is thought to be common in gra...
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Online Access: | http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3114065 http://www.ncbi.nlm.nih.gov/pubmed/21221651 https://doi.org/10.1007/s00442-010-1894-8 |
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ftpubmed:oai:pubmedcentral.nih.gov:3114065 2023-05-15T15:46:20+02:00 Increased searching and handling effort in tall swards lead to a Type IV functional response in small grazing herbivores Heuermann, Nicol van Langevelde, Frank van Wieren, Sipke E. Prins, Herbert H. T. 2011-01-11 http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3114065 http://www.ncbi.nlm.nih.gov/pubmed/21221651 https://doi.org/10.1007/s00442-010-1894-8 en eng Springer-Verlag http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3114065 http://www.ncbi.nlm.nih.gov/pubmed/21221651 http://dx.doi.org/10.1007/s00442-010-1894-8 © The Author(s) 2011 Plant-Animal interactions - Original Paper Text 2011 ftpubmed https://doi.org/10.1007/s00442-010-1894-8 2013-09-03T15:54:34Z Understanding the functional response of species is important in comprehending the species’ population dynamics and the functioning of multi-species assemblages. A Type II functional response, where instantaneous intake rate increases asymptotically with sward biomass, is thought to be common in grazers. However, at tall, dense swards, food intake might decline due to mechanical limitations or if animals selectively forage on the most nutritious parts of a sward, leading to a Type IV functional response, especially for smaller herbivores. We tested the predictions that bite mass, cropping time, swallowing time and searching time increase, and bite rate decreases with increasing grass biomass for different-sized Canada geese (Branta canadensis) foraging on grass swards. Bite mass indeed showed an increasing asymptotic relationship with grass biomass. At high biomass, difficulties in handling long leaves and in locating bites were responsible for increasing cropping, swallowing, and searching times. Constant bite mass and decreasing bite rate caused the intake rate to decrease at high sward biomass after reaching an optimum, leading to a Type IV functional response. Grazer body mass affected maximum bite mass and intake rate, but did not change the shape of the functional response. As grass nutrient contents are usually highest in short swards, this Type IV functional response in geese leads to an intake rate that is maximised in these swards. The lower grass biomass at which intake rate was maximised allows resource partitioning between different-sized grazers. We argue that this Type IV functional response is of more importance than previously thought. Text Branta canadensis PubMed Central (PMC) Canada Oecologia 166 3 659 669 |
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English |
topic |
Plant-Animal interactions - Original Paper |
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Plant-Animal interactions - Original Paper Heuermann, Nicol van Langevelde, Frank van Wieren, Sipke E. Prins, Herbert H. T. Increased searching and handling effort in tall swards lead to a Type IV functional response in small grazing herbivores |
topic_facet |
Plant-Animal interactions - Original Paper |
description |
Understanding the functional response of species is important in comprehending the species’ population dynamics and the functioning of multi-species assemblages. A Type II functional response, where instantaneous intake rate increases asymptotically with sward biomass, is thought to be common in grazers. However, at tall, dense swards, food intake might decline due to mechanical limitations or if animals selectively forage on the most nutritious parts of a sward, leading to a Type IV functional response, especially for smaller herbivores. We tested the predictions that bite mass, cropping time, swallowing time and searching time increase, and bite rate decreases with increasing grass biomass for different-sized Canada geese (Branta canadensis) foraging on grass swards. Bite mass indeed showed an increasing asymptotic relationship with grass biomass. At high biomass, difficulties in handling long leaves and in locating bites were responsible for increasing cropping, swallowing, and searching times. Constant bite mass and decreasing bite rate caused the intake rate to decrease at high sward biomass after reaching an optimum, leading to a Type IV functional response. Grazer body mass affected maximum bite mass and intake rate, but did not change the shape of the functional response. As grass nutrient contents are usually highest in short swards, this Type IV functional response in geese leads to an intake rate that is maximised in these swards. The lower grass biomass at which intake rate was maximised allows resource partitioning between different-sized grazers. We argue that this Type IV functional response is of more importance than previously thought. |
format |
Text |
author |
Heuermann, Nicol van Langevelde, Frank van Wieren, Sipke E. Prins, Herbert H. T. |
author_facet |
Heuermann, Nicol van Langevelde, Frank van Wieren, Sipke E. Prins, Herbert H. T. |
author_sort |
Heuermann, Nicol |
title |
Increased searching and handling effort in tall swards lead to a Type IV functional response in small grazing herbivores |
title_short |
Increased searching and handling effort in tall swards lead to a Type IV functional response in small grazing herbivores |
title_full |
Increased searching and handling effort in tall swards lead to a Type IV functional response in small grazing herbivores |
title_fullStr |
Increased searching and handling effort in tall swards lead to a Type IV functional response in small grazing herbivores |
title_full_unstemmed |
Increased searching and handling effort in tall swards lead to a Type IV functional response in small grazing herbivores |
title_sort |
increased searching and handling effort in tall swards lead to a type iv functional response in small grazing herbivores |
publisher |
Springer-Verlag |
publishDate |
2011 |
url |
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3114065 http://www.ncbi.nlm.nih.gov/pubmed/21221651 https://doi.org/10.1007/s00442-010-1894-8 |
geographic |
Canada |
geographic_facet |
Canada |
genre |
Branta canadensis |
genre_facet |
Branta canadensis |
op_relation |
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3114065 http://www.ncbi.nlm.nih.gov/pubmed/21221651 http://dx.doi.org/10.1007/s00442-010-1894-8 |
op_rights |
© The Author(s) 2011 |
op_doi |
https://doi.org/10.1007/s00442-010-1894-8 |
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Oecologia |
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166 |
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3 |
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659 |
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669 |
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1766381033554444288 |