Alert distance as an alternative measure of bird tolerance to human disturbance: implications for park design

Abstract

Animal tolerance to human approaches may be used to establish buffers for wildlife that can minimize the probability that animals will be disturbed by human activity. Alert distance (the distance between an animal and an approaching human at which point the animal begins to exhibit alert behaviours to the human) has been proposed as an indicator of tolerance mainly for waterbirds; however, little is known about its utility for other bird species. The factors that influenced alert distances of four bird species to pedestrian approaches in five large wooded fragments in the city of Madrid (Spain) were analysed. Location of human activity affected only Passer domesticus alert distances, which increased in the proximity of pathways. Habitat structure modified alert distances of all the species (Passer domesticus, Turdus merula, Columba palumbus, and Pica pica), increasing bird tolerance with greater availability of escape cover (shrub and coniferous cover, and shrub height). Alert distances varied among species, with large species being less tolerant of human disturbance than small ones. Alert distance appears to be a more conservative indicator of tolerance than flight distances, because it includes a buffer zone (the difference between alert and flight distance) in which birds may adapt their reaction to the behaviour of visitors. Alert distance may be used in the determination of minimum approaching areas, allowing people to enjoy their visit to parks, and birds to use patches for foraging and breeding without being displaced.

Untested assumptions about within-species sample size and missing data in interspecific studies

“…Here, we provided the first evidence that such sampling bias caused by shy-bold behaviors could occur in interspecific datasets. Flight distance is an inverse estimate of risk taking (Fernández--Juricic et al 2001Blumstein 2003). The same species consistently show the same escape behavior in the presence of a potential predator, and thus it makes biological sense to discriminate between risk prone and risk aversive species (Møller 2008a, b, c).…”

“…Data on flight initiation distances were collected to reflect risk taking, as risk taking birds allow an observer to approach them at a closer distance without fleeing than risk aversive birds (Burger and Gochfeld 1991a, b;Fernández-Juricic et al 2001Blumstein 2003). One of us (APM) used a modified technique developed by Fernández-Juricic, Blumstein and their co-workers to score risk taking behaviour in birds observed in France and Denmark during February-September 2006.…”

Defining spatial priorities for capercaillieTetrao urogalluslekking landscape conservation in south‐central Finland

“…AD has been recommended as the most appropriate measure on which to base buffer zones (Rodgers & Smith 1997, Fernández-Juricic et al 2001, 2005 but in several of our study species it is difficult or impossible to measure, either because of the distances involved or because birds on nests are hidden from view (see also González et al 2006). This probably explains why respondents less frequently provided opinions on 'static' disturbance distances for several species and must temper interpretation of the expert survey results.…”

“…For example, application of average measures of FID to prescribe buffer zones is unlikely to prevent all birds from being disturbed (Götmark et al 1989, Fernández-Juricic et al 2005) and most studies of behavioural reactions to a disturbance source record only FID, but buffer zones based directly on FID does not allow for any adaptation of wildlife to occur before disturbance affects animals' presence, and so AD probably has greater utility (Rodgers & Smith 1997, Fernández-Juricic et al 2001, 2005.…”

Alternative Approaches to Urban Natural Areas Restoration: Integrating Social and Ecological Goals

“…Some activities such as restoration stewardship may help support ecological goals, other activities such as walking along trails are largely benign, and activities such as collecting and dog-walking may threaten ecological goals if done at the wrong place or time (Fernandez-Jurucic et al 2001 ;Platt and Lill 2006 ) . All of these activities, however, may be legitimate and desirable social goals that people look to in urban nature and providing opportunities for them can help promote learning and build support for restoration programs (Miller 2006 ;Ryan et al 2001 ) .…”