Humans alter habitat selection of birds on ocean‐exposed sandy beaches

Abstract

Aim Resource‐selection functions (RSFs) can quantify and predict the density of animal populations across heterogeneous landscapes and are important conservation tools in areas subject to human disturbance. Sandy beach ecosystems have comparatively low habitat heterogeneity and structural relief in the intertidal zone, but intense human use. We aimed to develop predictive RSFs for birds on ocean‐exposed sandy beaches at two spatial scales, 25 ha (local scale) and 250 ha (landscape scale), and to test whether habitat selection of birds that commonly use the surf–beach–dune interface is influenced by the rates of human activities. Location Moreton and North Stradbroke Island, eastern Australia. Methods Avifauna and human activities were mapped on three sandy beaches covering 79 km of coastline for 15 months. Habitat characteristics of the surf–beach–dune interface were derived from remote sensing and ground surveys. RSFs were developed for 12 species of birds at two spatial scales: 25 ha (local scale) and 250 ha (landscape scale). Results At local (25 ha) and landscape scales (250 ha), dune dimensions and the extent and type of vegetation structure were important predictors of bird density. Adding the frequency of human activities improved the predictive power of RSFs, suggesting that habitat selection of birds on beaches is modified by human use of these environments. Human activities occurred mostly in the mid‐ to lower intertidal zone of the beach, overlapping closely with the preferred habitats of Silver Gulls (Larus novaehollandiae), Pied Oystercatchers (Haematopus longirostris), Red‐capped Plovers (Charadrius ruficapillus) and endangered Little Terns (Sternula albifrons). Main conclusions In addition to demonstrating the appropriateness of RSFs to the surf–beach–dune interface, our results stress the need for systematic conservation planning for these ecosystems, where ecological values have traditionally been subsidiary to the maintenance of sand budgets and erosion control.

Donor-Control of Scavenging Food Webs at the Land-Ocean Interface

“…We found that terrestrial avian scavengers had consumed nearly all of the fish carrion deposited on the beach within a week. Two factors appear most likely to contribute to this rapid and efficient scavenging on sandy beaches: a) raptors and other avian scavengers are abundant along the shoreline [69,70], and appear to have a specific search behaviour where individuals fly parallel to the base of the dunes where most carrion naturally strands (Schlacher, pers. obs.…”

Multiscale Burrow Site Selection of Gopher Tortoises (Gopherus polyphemus) in Coastal Sand Dune Habitat

“…Anthropogenic factors may be influential in highly disturbed areas. However, seldom have the interactions of all three of these factors been studied simultaneously, although several studies have attempted to discriminate their relative importance (Burger and Gochfeld, 1991;Gallant et al, 2009;Mahan and Yahner, 1996;Meager, Schlacher, and Nielsen, 2012;Peters and Otis, 2007). Work on river otters (Lontra canadensis), for example, suggested that environmental factors were more influential than anthropogenic factors in describing habitat selection patterns, but anthropogenic disturbances could indirectly affect habitat selection of otters by causing the loss of important habitat features (e.g.…”

Setback Distances as a Conservation Tool in Wildlife-Human Interactions: Testing Their Efficacy for Birds Affected by Vehicles on Open-Coast Sandy Beaches

“…The sites were selected based on four attributes particularly relevant for the study of interactions between vehicles and birds: 1) the eastern shores of both islands feature long stretches of exposed sandy beaches [32], 2) dunes and beaches of both islands are important feeding, roosting, and breeding sites for coastal birds [17,33,34], 3) motorised traffic is very intense on the beaches [35], and 4) this heavy traffic, most of it recreational, causes substantial disturbance to birds [20], resulting in conservation concerns about the impacts of traffic on birds and other wildlife [36,37]. …”

“…Our procedure of ranking disturbance response on an ordinal scale resembles methods used in similar bird-human interaction studies [40,41]. We also recorded the following contextual variables: number of individuals in the flock, beach width (m), wind speed (km h -1 ), temperature (°C), and state of the tide (hours since low water); these variables could potentially influence bird behaviour [17,20,32]. Focal observations lasted for 30 minutes or until an encounter with a vehicle, whichever came first.…”

“…Beaches and dunes are particularly attractive as sites for recreation, but also form unique habitats that contain species and assemblages vulnerable to vehicles: this juxtaposition of spatially concentrated, and often intense, motorised recreation with bio-diverse and malleable habitats results in magnified vehicle effects along many sandy shorelines [8,9]. Impacts of vehicles driven on beaches and dunes are reported from all levels of ecological organisation, including substantial habitat modifications [10–12], significant reductions in biodiversity and lower abundance of plants and invertebrates [13–15], and mortalities or significant disturbance of vertebrates [16,17]. Other processes demonstrated in terrestrial settings, such as the transportation of weeds, also presumably apply to beaches and dunes [18].…”