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Ecology, management and conservation in natural and modified habitats
RESEARCH ARTICLE

Defining separation zones for coastal birds at a wetland of global importance

Chevonne Reynolds https://orcid.org/0000-0002-2345-7017 A B G , Dominic A. W. Henry C D , Donovan R. C. Tye E and Nicholas D. Tye F
+ Author Affiliations
- Author Affiliations

A School of Animal, Plant and Environmental Sciences, University of the Witwatersrand, Private Bag 3, Wits 2050, Johannesburg, South Africa.

B FitzPatrick Institute of African Ornithology, DST-NRF Centre of Excellence, University of Cape Town, Rondebosch 7700, Cape Town, South Africa.

C Endangered Wildlife Trust, Johannesburg 1685, South Africa.

D Statistics in Ecology, Environment and Conservation, Department of Statistical Sciences, University of Cape Town, Rondebosch 7700, South Africa.

E Organisation for Tropical Studies, PO Box 33, Skukuza 1350, South Africa.

F C4 EcoSolutions, Tokai 7966, Cape Town, South Africa.

G Corresponding author. Email: chevonne.reynolds@gmail.com

Wildlife Research 48(2) 134-141 https://doi.org/10.1071/WR20098
Submitted: 12 June 2020  Accepted: 17 July 2020   Published: 3 September 2020

Abstract

Context: The disruption of normal activities by humans (i.e. ‘anthropogenic disturbance’) can have important behavioural, physiological and population effects on coastal birds. These negative effects include increased vigilance, increased energy expenditure and reduced nesting success. To overcome this, separation distances (e.g. buffers and setbacks) are often used to separate threatening stimuli, such as humans, from wildlife. However, in most instances the determination of separation distances are based on little empirical information. This is particularly true for Africa, which supports huge populations of Palearctic migrant shorebirds.

Aim: To determine suitable separation distances that will reduce anthropogenic disturbance to the coastal bird community at West Coast National Park, South Africa.

Methods: The distance at which a behavioural response (i.e. flight initiation distance, FID) occurred among 15 common coastal bird species when presented with an approaching human was measured. Linear mixed-effects models were used to determine the relationship between FID and body size, migratory status, intraspecific flock size, flock species richness, foraging behaviour and several environmental covariates.

Key results: Body mass was significantly and positively correlated with FID, indicating that larger birds are more sensitive to the anthropogenic stimulus. Furthermore, it was shown that migratory birds had longer FIDs, suggesting that they are less risk tolerant compared with resident birds. The distance at which the approach was initiated (i.e. the start distance, SD) was also significantly and positively correlated with FID, supporting the hypothesis that birds will flush early to avoid the potential negative consequences of fleeing too late. Finally, there was a novel significant effect of increasing wind speed on increasing FID, suggesting a thermoregulatory trade-off. There was no effect of foraging behaviour, flock size or flock composition on FID.

Conclusion: Based on these data, buffer distances for tidal habitats at West Coast National Park should be set at ~170 m.

Implications: Improved understanding of FID, and the morphological and behavioural predictors thereof, will enable West Coast National Park and other protected areas to designate separation distances or buffer zones that reduce the negative effects of anthropogenic disturbance on shorebird communities.

Additional keywords: coastal habitat, disturbance, flight initiation distance, shorebirds, starting distance, wetlands.


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