Nesting tree characteristics of heronry birds of urban ecosystems in peninsular India: implications for habitat management

Abstract

Wetland ecosystems, particularly the mangrove forest, are the primary wild habitat of heronry birds. However, urban ecosystems have become a favorite breeding habitat of these birds. To provide inputs into the habitat management for conservation of these birds, we investigated the quantitative and qualitative characteristics of nesting trees of heronry birds in the urban environment of the North Kerala region of peninsular India. Census on nesting trees was done in 3 major microhabitats of the urban ecosystem: avenues of national highways and towns, nonresidential plots, and residential areas apart from the mangrove islets in the peri-urban locality. The study found that 174 trees of 22 species hosted 1,928 heronry bird nests in the urban habitats; mangrove forests, although plentiful in the study area, hosted only about 20% of the total nests encountered in the study. Rain trees Samanea saman (43.7%) were the most available nesting tree. The greatest number of nests and nesting trees were encountered on the roads of urban areas, followed by nonresidential areas and residential areas. The differences in the observed frequencies of nesting trees in 3 microhabitats and in 3 types of roads (national highways > state highways > small pocket road) were significant. Canopy spread, girth size, and quality of the trees predicted the tree selection of the heronry birds in urban environments. Therefore, we recommend proper management and notification of the identified nesting trees as protected sites for the conservation of herorny birds.

Heronry distribution and site preference dynamics of tree-nesting colonial waterbirds in Tamil Nadu

“…Trees located along roadsides (national highways/state highways), near residential areas and in non-residential areas (inside campuses) have been recorded as excellent nesting habitats for colonial nesting waterbirds (Subramanya, 1996;Sashikumar & Jayarajan, 2007;Roshnath & Sinu, 2017). The present study corroborates this.…”

“…The habitat selection and population dynamics of colonial nesting waterbirds are influenced by various factors, among which nesting tree quality is one of the predominant criteria (Baxter & Fairweather, 1998;Roshnath & Sinu, 2017). Vachellia nilotica was found in most of the wetlands planted by the forest department in the early 1960s to meet the demand for fuelwood (Wilson, 1979).…”

Diversity of feeding habitats and diet composition in the turtle doves Streptopelia turtur to buffer loss and modification of natural habitats during breeding season

“…These habitats play a very important role in the survival of the species. In fact, crops offer an important food resources, while the landscape fixed elements, such as trees, provide a capital support for nesting (Rocha and Quillfeldt, 2015, Hanane, 2016, Roshnath and Sinu, 2017). In wintering grounds, seeds are the main nutrients for turtle doves (Guy, 1991).…”

Diversity, Habitat Utilization and Nesting Characteristics of Waterbirds in and around Maduru Oya Reservoir in Maduru Oya National Park, Sri Lanka

“…Trees around the reservoir were identified as the most utilized habitat type for both breeding and resting purposes. Colonial waterbirds of Orders Ciconiiformis and Pelicaniformis nest together in large aggregations called mixed breeding colonies of up to thousands of nests [33]. Nesting areas must provide protection from predators, nesting materials, as well as sufficient quantity and quality of foraging habitat and large waterbirds prefer the trees with higher DBH for building their nests [47] [48].…”

“…Random quadrats (10 × 10 m) were laid for the sampling of nesting trees. The canopy of each nesting tree was visually divided into three approximately equal parts as upper canopy layer, middle canopy layer and lower canopy layer [33] (Figure 3(a)). Number of nests belonging to each waterbird species in each layer of the canopy was counted.…”