Figure 2. Habitat use of 132 adult female bottlenose dolphins in Shark Bay in 286 km² study area.

Image shows sightings of spongers (white circles, N = 16 spongers, 900 sightings, 52.9±12.6 per sponger) with non-spongers (red circles, N = 116 non-spongers, 9,742 sightings, 84.7±11.3 per female) in our main study area using only one sighting per day per female. In both maps, spongers are placed on top of the other females. Three zones are represented: channels (hatched lines), deep water (cross-hatched) and shallow moderate depth (open). Spongers were sighted 84.1±2.8% of the time in channels. Non-spongers were sighted 17.0±2.2% of the time in channels. If the primary area (>50% of sightings) is used to define adult female density by zone, then 32 females use channels as their primary area (female density = 0.34 females per km²), including all spongers and 16 non-spongers; 48 females use deep water as their primary area (0.60 females per km²) and 44 females use shallow-moderate depths as their primary area (0.40 females per km²). Seven females could not be assigned to a primary area. The map shows where spongers were sighted, but sponge foraging only occurred in channel habitats and, on rare occasion, in the deep (>7 m) northwest portion of the study area.