Woodlots in agricultural landscapes maintain a high diversity of birds
Birds are suitable bioindicators that tell about the state of the environment. From a global perspective, the number of populations of several bird species in agricultural landscapes has significantly reduced. The cause is mainly the intensification of agriculture.
Photo: Agricultural landscape with scattered woody vegetation, author Jan Řezáč
Based on the most recent scientific studies, environmental factors at the landscape level have the most significant impact on the diversity and distribution of organisms. These factors are especially critical in a uniform agricultural landscape, where species exist within a patchwork of isolated habitats connected by migrating individuals.
Woody vegetation, such as groups of trees, solitary trees, draws, or forest edges, plays a critical role in providing nesting and feeding habitats for birds in agricultural landscapes. These plant communities also offer shelter from predators and opportunities for migration through open areas.
As a result, they are an essential part of the Territorial System of Ecological Stability (ÚSES) today. This system includes corridors that connect larger habitat areas (known as biocentres) and interaction elements, which are isolated fragments of woody vegetation stands.
Photo: Common bunting
Woodlots play a specific role in ecological systems. They are significant as they provide stability in the ecosystem, creating favourable conditions for various animal species such as birds, by offering shelter, food, and a place for reproduction.
In forest ecosystems, classic ornithological monitoring methods are commonly used to gather information about the composition of bird species. These methods include mapping nesting areas, as well as using point and line transects. In addition to these traditional methods, alternative approaches used in studying other vertebrate groups, such as acoustic monitoring using recorders and camera traps, can also be employed.
Monitoring birds using camera traps is a valuable method for studying bird communities. It has great potential for studying and monitoring rare species, investigating nest predation, and researching the behavioural patterns of individual species.
When using camera traps in ornithological research, it is important to consider how the results obtained through this method compare to those obtained through traditional ornithological monitoring. We need to determine whether camera traps can be used as a supplement to traditional methods or if they can be used independently for specific ornithological studies.
Photo: Agricultural landscape with scattered woody vegetation, author Jan Řezáč
The scientists from Mendel University in Brno conducted research on this topic and published their findings in the article titled „Mohou být fotopasti vhodnou metodou pro studium avifauny v remízcích jako specifických porostů dřevinné vegetace v kulturní krajině?“ (Could camera traps be a suitable tool for studying avifauna in woodlots as specific stands of woody vegetation in cultural landscape?). The article was published in the journal Zprávy lesnického výzkumu 2/2024.
The scientists have set the following goals: 1. To determine how the representation of bird species detected using different monitoring methods (such as camera traps and transects) differs. 2. To identify the types of bird predators and disturbers found in the area. 3. To determine which characteristics of the area have the greatest influence on bird communities.
The researchers selected 11 experimental plots in the South Moravia and Vysočina border area to compare bird monitoring methods using linear transects and camera traps. These plots are isolated and situated in the wooded, horizontally divided landscape of Lomnicka.
Photo: Blackbird
In the tree draws, scientists observed a total of 45 bird species from 7 orders and 22 families. Camera traps recorded a total of 2366 bird individuals, while line monitoring detected 461 bird individuals.
A total of 45 species of birds from seven orders and 22 families were recorded in the observed woodlots. The most numerous was the songbirds with a total of 31 species.
The number of bird species captured on camera traps ranged from 5 to 14 species per woodlot. The frequency of occurrence in individual captures varied from 1 to 1103 photographed individuals.
The number of bird species recorded using the line method of bird monitoring ranged from 9 to 18 species, and the abundance of individual bird species varied from 1 to 91 individuals.
The most abundant species was the common bunting, with 92 individuals recorded using the line method of bird monitoring. The blackbird was the most frequently recorded species, with 1103 records, using the camera trap method.
Photo: Woodlot in the agricultural landscape, author Jan Řezáč
Some species were recorded using the line monitoring method only, for example, the garden warbler, some using camera traps, for example, the spotted nutcracker, or the tawny owl and other bird species were recorded using both methods.
Using the camera trap method, more bird species were detected in narrower and longer stands, as opposed to higher and wider draws where more bird species were detected using a line transect.
Taller and wider woodlots attracted a greater variety of forest generalists and specialists, such as black woodpecker or Eurasian treecreeper, mostly detected using the line transect method.
In smaller woodlots with short trees and a dense shrub layer, there were species nesting in the shrubs or living in hiding, such as the red-backed shrike, garden warbler, or long-tailed tit. There were also species specialized for open landscapes, like the common bunting.
Photo: Spotted nutcracker
The two methods differ in that the line method is better for recording birds in treetops, while the phototrap method is more effective for capturing species that are often found on the ground or in the forest understory.
In tree stands with narrower, longer, and lower vegetation, the photo trap method recorded the highest number of bird disturbers and predators. However, the analyses did not confirm a clear link between the frequency of occurrence and the abundance of bird species in the area. The association between these particular areas and bird predators is likely due to the high activity of predators in these areas, either for foraging or migration.
In conclusion, the researchers emphasized the importance of choosing the right monitoring method for accurately assessing the impact of bird feeders on bird communities. They found that the camera trap method has limitations and tends to overestimate the presence of certain bird groups, particularly those that inhabit forest undergrowth. However, they also noted that this method can be useful for monitoring birds in areas with dense undergrowth vegetation.
The paper “Could camera traps be a suitable tool for studying avifauna in woodlots as specific stands of woody vegetation in cultural landscape?“ („Mohou být fotopasti vhodnou metodou pro studium avifauny v remízcích jako specifických porostů dřevinné vegetace v kulturní krajině?“) can be downloaded here.
Authors: Denisa Dvořáková, Jan Šipoš, Jiří Stehno, Josef Suchomel, Mendel University in Brno (Mendelova univerzita v Brně), e-mail: denisa.dvorakova@mendelu.cz
According to the original document prepared by Jan Řezáč, VÚLHM, v. v. i., e-mail: rezac@vulhm.cz