Habitat use of waterfowl assemblages in Viikki reserve : a comparison of grazed and ungarzed shorelines

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Title: Habitat use of waterfowl assemblages in Viikki reserve : a comparison of grazed and ungarzed shorelines
Author: Samooty, Ladan
Other contributor: Helsingin yliopisto, Maatalous-metsätieteellinen tiedekunta, Metsätieteiden laitos
University of Helsinki, Faculty of Agriculture and Forestry, Department of Forest Sciences
Helsingfors universitet, Agrikultur- och forstvetenskapliga fakulteten, Institutionen för skogsvetenskaper
Publisher: Helsingfors universitet
Date: 2013
Language: eng
URI: http://urn.fi/URN:NBN:fi:hulib-201507212065
Thesis level: master's thesis
Discipline: Skoglig ekologi och resurshushållning
Forest Ecology and Management (Community ecology / Ecosystem management)
Metsien ekologia ja käyttö
Abstract: Domestic cattle grazing as a disturbance factor to the vegetation structure is investigated. It is concluded that the process of heterospecific attraction plays as important a role as vegetation structure in predicting waterfowl assemblage patterns. The study site, an estuarine wetland in an urban zone in Helsinki, is studied during one staging period. Two sets of shorelines are focused on, grazed and ungrazed. Avian assemblages are compared in both types of shorelines based on variables of community structure and habitat resource use. The two most influential variables are aquatic invertebrate biomass index as food supply, and bare shoreline proportion as habitat structure indicator. The process of competition as regulating factor in forming avian aggregations is ruled out by confirming that sufficient amounts of habitat resources, food and space are available. The co-occurrence patterns of foraging guilds are analyzed. Heterogeneous vegetation structure, combined with social attraction, influences avian distribution patterns. Niche partitioning is absent across the whole landscape as invertebrate food resource is not a limiting factor. Microhabitat use within plots is evenly distributed. The constantly popular microhabitats are sections of the grazed shorelines where resource partitioning is absent. Avian habitat preferences are shaped by extent of available bare shoreline and the presence of other waterfowl. The latter effect is confirmed both as conspecific and heterospecific attraction. It is the first time this wetland, which is also a designated Natura 2000 and Ramsar site, is being investigated for wildlife community dynamics. The site does not suffer from major environmental threats and has potential for more waterfowl consumers. In view of its international significance, this and similar research can aid urban planners in Reserve management to enhance avian diversity towards attracting species of more conservation concern.
Subject: assemblage
avian behavior
habitat structure
foraging guild
habitat preference
heterospecific attraction
interspecific dynamics
invertebrate food
vegetation structure

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