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The effect of semi natural grasslands on bird diversity and abundance in agricultural landscapes

Blasiusson, Sandra (2017) BIOK01 20171
Degree Projects in Biology
Popular Abstract
Semi natural grasslands increase bird diversity on crop fields

During recent decades populations of farmland bird species have declined dramatically across Europe. The main cause of this decline has been established to be agricultural intensification. This intensification has led to a decrease in heterogeneity, i.e. habitat variation, in the agricultural landscape through increased field sizes, which reduces the amount of field margins that provide an important habitat for foraging and nesting, and the conversion of non-crop habitats to crop fields.

64 % of Swedish common farmland bird species require non-crop habitats for foraging, refuge, nesting and perching/singing. In Sweden one of the main results of agricultural... (More)
Semi natural grasslands increase bird diversity on crop fields

During recent decades populations of farmland bird species have declined dramatically across Europe. The main cause of this decline has been established to be agricultural intensification. This intensification has led to a decrease in heterogeneity, i.e. habitat variation, in the agricultural landscape through increased field sizes, which reduces the amount of field margins that provide an important habitat for foraging and nesting, and the conversion of non-crop habitats to crop fields.

64 % of Swedish common farmland bird species require non-crop habitats for foraging, refuge, nesting and perching/singing. In Sweden one of the main results of agricultural intensification has been the loss of semi natural grasslands (SNG’s), i.e. permanent pastures, and other non-crop habitats. Grasslands in general have been suggested to be of importance to bird species diversity and abundance in a homogenous agricultural landscape. Thus, to further investigate the importance of SNG’s, we investigated the difference in bird species diversity and abundance in and around fields adjacent to SNG’s (SNG fields) and fields surrounded by other crop fields (control fields).

Species diversity differed between May and July
We found that there was a significant difference in species diversity depending on the presence of SNG’s. There were generally more species around the SNG fields than the control fields. When applying Shannon’s diversity index to the analysis however, the results differed between May and July which were the two periods in 2016 when data collection took place. Now we could only find significantly higher species diversity on SNG fields in May. However, there was also a significantly lower species diversity in July compared to May. This may be due to the breeding season of passerine birds, in July most of these species have stopped singing to attract mates and may therefore be more difficult to spot, or they may have moved to different types of habitats.

The abundance of birds was only affected by the presence of SNG’s for a few species where some responded negatively and others positively. Most notably were the skylark Alauda arvensis which responded negatively to the SNG’s, and, in comparison, the hooded crow Corvus cornix which had a strong positive response to the SNG’s. These responses can easily be attributed to the ecology of the species, skylarks generally avoid vertical structures such as trees and bushes that were often present on the SNG’s due to predation while the hooded crow is generally a tree nesting species and thus attracted to SNG’s were these can be present.

In conclusion we cannot attribute any general effect of SNG’s on abundance of birds, rather the ecology of a species will determine in which habitat it is most abundant. However our overall results further strengthen the claim that permanent grasslands have a positive effect on bird species diversity in agricultural landscapes. Reestablishment of such habitats could hence be used as a tool to reverse the declines of some farmland bird species.


Supervisor: Matthias Tschumi
Bachelor's Degree Project 15p in Biology, 2017
Department of Biology, Lund University (Less)
Please use this url to cite or link to this publication:
author
Blasiusson, Sandra
supervisor
organization
course
BIOK01 20171
year
type
M2 - Bachelor Degree
subject
language
English
id
8925872
date added to LUP
2017-09-18 12:11:14
date last changed
2017-09-19 09:03:37
@misc{8925872,
  author       = {Blasiusson, Sandra},
  language     = {eng},
  note         = {Student Paper},
  title        = {The effect of semi natural grasslands on bird diversity and abundance in agricultural landscapes},
  year         = {2017},
}