Disturbance of a rare seabird by ship-based tourism in a marine protected area

Abstract

Managers of marine protected areas (MPAs) must often seek ways to allow for visitation while minimizing impacts to the resources they are intended to protect. Using shipboard observers, we quantified the “zone of disturbance” for Kittlitz’s and marbled murrelets (Brachyramphus brevirostris and B. marmoratus) exposed to large cruise ships traveling through Glacier Bay National Park, one of the largest MPAs in North America. In the upper reaches of Glacier Bay, where Kittlitz’s murrelets predominated, binary logistic regression models predicted that 61% of all murrelets within 850 m perpendicular distance of a cruise ship were disturbed (defined as flushing or diving), whereas in the lower reaches, where marbled murrelets predominated, this percentage increased to 72%. Using survival analysis, murrelets in both reaches were found to react at greater distances when ships approached indirectly, presumably because of the ship’s larger profile, suggesting murrelets responded to visual rather than audio cues. No management-relevant covariates (e.g., ship velocity, route distance from shore) were found to be important predictors of disturbance, as distance from ship to murrelet accounted for > 90% of the explained variation in murrelet response. Utilizing previously published murrelet density estimates from Glacier Bay, and applying an average empirical disturbance probability (68%) out to 850 m from a cruise ship’s typical route, we estimated that a minimum of 9.8–19.6% of all murrelets in Glacier Bay are disturbed per ship entry. Whether these disturbance levels are inconsistent with Park management objectives, which include conserving wildlife as well as providing opportunities for visitation, depends in large part on whether disturbance events caused by cruise ships have impacts on murrelet fitness, which remains uncertain.

Protected area use by two sympatric marine predators repopulating their historical range

“…remote areas, low human visitation, limited commercial activity). When marine carnivores are on land they can be disturbed by visual, aural and olfactory cues whether approached from land or sea (H. , Cowling et al 2015, Marcella et al 2017 or from the air by piloted and remotely operated aircraft (Born et al 1999, Bevan et al 2018, McIntosh et al 2018a), which at worst may have lethal consequence (Back et al 2018). An effective way to reduce disturbance to marine carnivores on land is to restrict access and modify behaviour of humans, for example 2.…”

What to expect from alternative management strategies to conserve seabirds? Hints from a dynamic modelling framework applied to an endangered population

“…Disturbance caused by tourism and oil spills had minor effects on the population trends, probably because visits occur mostly in July and August when chicks are no longer in the nest (Silva, 2015; Fernandes, 2016) and the low probability of oil spills considered for the simulated period. However, tourism in natural areas continues to increase with negative consequences (Marcella et al ., 2017), and a single oil spill event might have dramatic consequences for this relict population (Velando et al ., 2005; Munilla et al ., 2011).…”

Spatiotemporal variation in disturbance impacts derived from simultaneous tracking of aircraft and shorebirds

“…In the field, a range finder can be used to measure distances between disturbance sources and animals (e.g. Marcella et al., 2017), but studies have rarely obtained sufficient sample sizes to reliably estimate flight probability curves. In addition, by using biologging techniques, it is possible to follow animals over longer time periods and study longer term impacts of disturbance, such as additional displacement (Brambilla & Brivio, 2018; Linssen et al., 2019).…”

“…Distance–response relationships describe the flight probability and the flight costs of an animal as a function of the minimal distance at which a disturbance source passes by, and would be suitable for assessing such disturbance impacts. However, they have only been quantified for a limited number of species and disturbance sources, including for disturbance of geese and Dall's sheep by aircraft (Frid, 2003; Marcella, Gende, Roby, & Allignol, 2017; Preisler, Ager, & Wisdom, 2006; Ward, Stehn, Erickson, & Derksen, 1999).…”