Mountain goat response to helicopter overflights in Alaska

Abstract

The number of helicopter flights used to gain access to backcountry has increased in recent years. Biologists, land managers, and the public have expressed concern about disturbance impacts to mountain goats (Oreamnos americanus) resulting from helicopter activity. We recorded behavioral responses of 122 groups of mountain goats from 347 helicopter overflights at 4 geographic areas in Alaska and analyzed responses in relation to distance and angle from helicopters to mountain goats, reproductive class, season, and area of study. We used multinomial logistic regression modeling combined with a bootstrap randomization procedure to identify factors associated with increased probability of mountain goats being in 1 of the 4 behavioral response categories during helicopter overflights. The probability of a goat group being disturbed was inversely related to distance of the helicopter from the group. Odds of disturbance increased by a factor of 1.25 for every 100‐m reduction in approach distance. Approach distances resulting in >90% probability of maintenance were significantly larger where mountain goats had received less prior exposure to helicopters. When mountain goats were disturbed during overflights, a second analysis (i.e., gamma regression model with inverse link function) estimated elapsed time until mountain goats returned to maintenance behavior. The length of time that a goat remained in a disturbed state following overflight did not depend upon any of the covariates; mountain goats remained in a disturbed state for an average of 30.7 seconds (95% C***I, 25.7–35.9 seconds). The results offer land managers an opportunity to evaluate risk for permitting helicopter activity.

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“…Goldstein et al (2005) defined the awareness behaviour as the state where the goat stays with its head leaned toward some kind of stimulus. Quenette (1990) reported that animals standing aware are a sign of surveillance and that they stop what they are doing during their ongoing activity, raising their head and visually scanning the environment.…”

Screening Radiolocation Datasets for Movement Strategies With Time Series Segmentation

“…increasing their movements and vigilant behaviour, decreasing foraging efficiency by shifting habitat and altering grouping patterns (Delaney et al 1999, Linklater & Cameron 2002, Patenaude et al 2002, Frid 2003, Southwell 2005, Tracey & Fleming 2007. Under certain conditions animals can become habituated to the disturbance (Miller & Gunn 1980, Stockwell et al1991, Hughes et al 2008) but the disturbance effects normally increase with increasing intensity of the harassment (Bayne et al 2000, Goldstein et al 2005. The proximity and the direction of the aircraft in relation to the animals influence the effect of the disturbance, with more severe reactions by the animals to direct approaches and short distances to the aircraft (Stockwell et al 1991, Frid 2003.…”

“…The effects of helicopter disturbance on large mammals have been documented for ungulates, mostly from observing the animals during over-flights by helicopters in recreational or exploration traffic (Stockwell et al1991, Coˆte1 996) and during aerial surveys (Bleich et al 1990, 1994, Linklater & Cameron 2002. The experimental overflights show that ungulates react more severely to threatening approaches (more direct approaches or at a shorter distance; Frid 2003, Goldstein et al 2005, Tracey & Flemming 2007 but little is documented on the behaviour in large mammals in response to a helicopter directly approaching a single focal animal during research projects. The effects of direct helicopter approaches on large carnivores have not yet been reported even though routine helicopter approaches are used in many large carnivore projects.…”

Responses of mountain goats to heliskiing activity: Movements and resource selection.

“…In some areas o f mountain goat range, including B.C., this disturbance is largely related to the expanding helicopter-supported recreation industry (Denton 2000, W ilson and Shackleton 2001, Festa-Bianchet and Cote 2008. Several studies have shown helicopter disturbance to cause short-term stress responses in mountain goats including fleeing, decreased foraging, and increased vigilance (Foster and Rahs 1983, Cote 1996, Goldstein et al 2005. These short-term impacts on behaviour could translate to consequences to movement rates, range use and ultimately survival and population productivity (W ilson andShackleton 2001, Festa-Bianchet andCote 2008).…”

“…Because there is often a lack o f standardization in their m easurem ent across the literature, for the purposes o f my thesis, short-term responses refer to the reactions o f animals to helicopters that occur directly following helicopter approaches and are verified by observer-based studies. The temporal scale o f reactions observed in these studies range from 15 minutes following disturbance (Goldstein et al 2005) to several hours following disturbance (Cote 1996). M edium-term responses are the responses to helicopter activity that are evident when observing the daily to seasonal behaviour patterns and habitat use o f animals that have been exposed to helicopter activity (e.g., changes in m ovem ent behaviour, temporary displacement).…”