The Ecological Conditions That Favor Tool Use and Innovation in Wild Bottlenose Dolphins (Tursiops sp.)

Abstract

Dolphins are well known for their exquisite echolocation abilities, which enable them to detect and discriminate prey species and even locate buried prey. While these skills are widely used during foraging, some dolphins use tools to locate and extract prey. In the only known case of tool use in free-ranging cetaceans, a subset of bottlenose dolphins (Tursiops sp.) in Shark Bay, Western Australia habitually employs marine basket sponge tools to locate and ferret prey from the seafloor. While it is clear that sponges protect dolphins' rostra while searching for prey, it is still not known why dolphins probe the substrate at all instead of merely echolocating for buried prey as documented at other sites. By ‘sponge foraging’ ourselves, we show that these dolphins target prey that both lack swimbladders and burrow in a rubble-littered substrate. Delphinid echolocation and vision are critical for hunting but less effective on such prey. Consequently, if dolphins are to access this burrowing, swimbladderless prey, they must probe the seafloor and in turn benefit from using protective sponges. We suggest that these tools have allowed sponge foraging dolphins to exploit an empty niche inaccessible to their non-tool-using counterparts. Our study identifies the underlying ecological basis of dolphin tool use and strengthens our understanding of the conditions that favor tool use and innovation in the wild.

Social networks reveal cultural behaviour in tool-using dolphins

“…procure and wear basket sponges on their beaks while lightly scouring the seafloor for prey in deep (8-13 m) channels ( Fig. 1) [9][10][11][12] . Sponging is the bestdocumented case of tool use by wild cetaceans and is unique among wildlife in that only a small subset of the population uses tools.…”

“…This exceptional case of tool-use heterogeneity allows us to test for preferential affiliation based on tool-use. To date, 55 dolphins have been documented habitually using sponges in the eastern gulf of Shark Bay 12 , although sponging also occurs in the western gulf 13 . Only calves of spongers become spongers (24 offspring to date), but 8 offspring of spongers never adopted sponging.…”

“…The main critique of the exclusion method is that it tries to prove the null and produces false negatives because ecological factors often contribute to cultural behaviour 16,20 . Regardless, this method is not appropriate for identifying sponge tool-use as cultural behaviour, as environmental factors cannot be excluded; the deep channels where sponging occurs have high basket sponge density 21 and prey that are difficult to detect without sponge tools 12 . Many, but not all, animals that use these channels specialize in sponging and spongers spend more time using tools than any non-human animal 10 .…”

The High Cost of Motherhood: End-Lactation Syndrome in Southern Sea Otters (Enhydra Lutris Nereis) on the Central California Coast, Usa

“…Like many tool using species, ecological factors (such as the physical characteristics of prey) play a critical role in explaining complex behaviors (Collins andMcGrew 1987, Patterson andMann 2011). Future studies would benefit from quantifying the cost and benefits of learning to use tools, as well as further exploration to how individuals learn to use tools.…”

Trazando los orígenes del comportamiento simbólico a través del registro arqueológico paleolítico<br /><em>Tracking the origins of symbolic behavior through the Paleolithic archaeological record</em>

“…En el caso de los útiles, hoy en día, sabemos que distintos primates utilizaron herramientas (Schick y otros, 1999;Van Schaik, Deaner y Merrill, 1999;Mercader, Panger y Boesch, 2002), especialmente monos capuchinos (Fragaszy y otros, 2004;Ferreira, Emidio y Jerusalinsky, 2010;Proffitt y otros, 2016) y macacos (Gumert, Kluck y Malaivijitnond, 2009;Haslam y otros, 2013), además de otros animales como peces, osos y elefantes (Hart y otros, 2001;Deecke, 2012;Patterson y Mann, 2011) para algunas de sus funciones básicas, como la alimentación o la higiene personal y, por lo tanto, la humanidad no es la única que emplea o ha empleado herramientas.…”