Foraging niche segregation in Malaysian babblers (Family: Timaliidae)

Abstract

Tropical rainforests are considered as hotspots for bird diversity, yet little is known about the system that upholds the coexistence of species. Differences in body size that are associated with foraging strategies and spatial distribution are believed to promote the coexistence of closely related species by reducing competition. However, the fact that many babbler species do not differ significantly in their morphology has challenged this view. We studied the foraging ecology of nine sympatric babbler species (i.e., Pellorneum capistratum, P. bicolor, P. malaccense, Malacopteron cinereum, M. magnum, Stachyris nigriceps, S. nigricollis, S. maculata, and Cyanoderma erythropterum) in the Krau Wildlife Reserve in Peninsular Malaysia. We investigated; i) how these babblers forage in the wild and use vegetation to obtain food, and ii) how these trophically similar species differ in spatial distribution and foraging tactics. Results indicated that most babblers foraged predominantly on aerial leaf litter and used gleaning manoeuvre in intermediate-density foliage but exhibited wide ranges of vertical strata usage, thus reducing interspecific competition. The principal component analysis indicated that two components, i.e., foraging height and substrate are important as mechanisms to allow the coexistence of sympatric babblers. The present findings revealed that these bird species have unique foraging niches that are distinct from each other, and this may apply to other insectivorous birds inhabiting tropical forests. This suggests that niche separation does occur among coexisting birds, thus following Gause’ law of competitive exclusion, which states two species occupying the same niche will not stably coexist.

Niche partitioning of sympatric penguins by leapfrog foraging appears to be resilient to climate change

“…Vertical niche partitioning has been found in a range of diving (Cimino et al., ; Kokubun et al., , ; Mori & Boyd, ) and arboreal (MacArthur, ; Mansor & Ramli, ; Slagsvold, ) species where they occur in sympatry. We found that, while dive depths overlapped considerably, chinstraps dived to significantly deeper depths than Adélies.…”

“…Competition within and between species exerts strong influences over population dynamics, community structure and species distributions (Hardin, 1960;MacArthur, 1968). The potential for competition is particularly intense in communities where closely related species breed sympatrically at high densities and share limited food resources (MacArthur, 1968).…”

“…Competition within and between species exerts strong influences over population dynamics, community structure and species distributions (Hardin, 1960;MacArthur, 1968). The potential for competition is particularly intense in communities where closely related species breed sympatrically at high densities and share limited food resources (MacArthur, 1968). Interspecific competition may be reduced by differentiating niche space along multidimensional axes such as diet (Croxall, Prince, & Reid, 1997), foraging distribution (MacArthur, 1958;Wilson, 2010) and allochrony (i.e., differences in the timing of activity among species).…”

Short Communication: Roosting behavior of Wintering Barn Swallow (Hirundo rustica) in Peninsular Malaysia

“…Observations were performed by only one observer to reduce bias at selected service wires in the town using a modified scan sampling method at 5-minute intervals following Altmann (1974), Martin and Bateson (1993), and Samson and Ramakrishnan (2016). Only the initial behaviors (i.e., the first sighting of an individual bird) were recorded to avoid problems related to non-independent data (Mansor and Ramli 2017;Mansor et al 2018a). Subsequent observations of foraging in the same bird were assumed to be correlated and were thus ignored (MacNally 1994).…”

Occupancy patterns and upper range limits of lowland Bornean birds along an elevational gradient

“…Our lack of detailed ecological knowledge of most species makes even hypothesizing likely networks of competitors difficult (Jankowski et al, 2012), beyond the relatively coarse metric of foraging guild or at the limited scale of genus. Diffuse competition may often result in niche differentiation based on foraging manoeuvres and strata rather than area occupancy, even among morphologically similar species with similar diets, as has been found for babblers (Timaliidae) in Malaysia (Mansor & Ramli, 2017;Styring, Ragai, Zakaria, & Sheldon, 2016). Competition may also be difficult to detect because elevational range overlap of strongly competing species may be effectively eliminated.…”