1
|
Ward-Fear G, Bruny M, Rangers TB, Forward C, Cooksey I, Shine R. Taste aversion training can educate free-ranging crocodiles against toxic invaders. Proc Biol Sci 2024; 291:20232507. [PMID: 39137886 DOI: 10.1098/rspb.2023.2507] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2023] [Accepted: 05/31/2024] [Indexed: 08/15/2024] Open
Abstract
Apex predators play critical ecological roles, making their conservation a high priority. In tropical Australia, some populations of freshwater crocodiles (Crocodylus johnstoni) have plummeted by greater than 70% due to lethal ingestion of toxic invasive cane toads (Rhinella marina). Laboratory-based research has identified conditioned taste aversion (CTA) as a way to discourage consumption of toads. To translate those ideas into landscape-scale management, we deployed 2395 baits (toad carcasses with toxin removed and containing a nausea-inducing chemical) across four gorge systems in north-western Australia and monitored bait uptake with remote cameras. Crocodile abundance was quantified with surveys. Free-ranging crocodiles rapidly learned to avoid toad baits but continued to consume control (chicken) baits. Toad invasion at our sites was followed by high rates of crocodile mortality (especially for small individuals) at a control site but not at nearby treatment sites. In areas with high connectivity to other waterbodies, repeated baiting over successive years had continuing positive impacts on crocodile survival. In summary, we succeeded in buffering the often-catastrophic impact of invasive cane toads on apex predators.
Collapse
Affiliation(s)
- Georgia Ward-Fear
- School of Natural Sciences, Macquarie University, Sydney, New South Wales 2109, Australia
| | - Miles Bruny
- Department of Biodiversity, Conservation and Attractions, Wanneroo, Western Australia 6065, Australia
| | - The Bunuba Rangers
- Bunuba Dawangarri Aboriginal Corporation, Fitzroy Crossing, Western Australia 6765, Australia
| | - Clare Forward
- Department of Biodiversity, Conservation and Attractions, Wanneroo, Western Australia 6065, Australia
| | - Ian Cooksey
- Department of Biodiversity, Conservation and Attractions, Wanneroo, Western Australia 6065, Australia
| | - Richard Shine
- School of Natural Sciences, Macquarie University, Sydney, New South Wales 2109, Australia
| |
Collapse
|
2
|
De Meester G, Van Linden L, Torfs J, Pafilis P, Šunje E, Steenssens D, Zulčić T, Sassalos A, Van Damme R. Learning with lacertids: Studying the link between ecology and cognition within a comparative framework. Evolution 2022; 76:2531-2552. [PMID: 36111365 DOI: 10.1111/evo.14618] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2022] [Revised: 08/10/2022] [Accepted: 08/21/2022] [Indexed: 01/22/2023]
Abstract
Cognition is an essential tool for animals to deal with environmental challenges. Nonetheless, the ecological forces driving the evolution of cognition throughout the animal kingdom remain enigmatic. Large-scale comparative studies on multiple species and cognitive traits have been advanced as the best way to facilitate our understanding of cognitive evolution, but such studies are rare. Here, we tested 13 species of lacertid lizards (Reptilia: Lacertidae) using a battery of cognitive tests measuring inhibitory control, problem-solving, and spatial and reversal learning. Next, we tested the relationship between species' performance and (a) resource availability (temperature and precipitation), habitat complexity (Normalized Difference Vegetation Index), and habitat variability (seasonality) in their natural habitat and (b) their life history (size at hatching and maturity, clutch size, and frequency). Although species differed markedly in their cognitive abilities, such variation was mostly unrelated to their ecology and life history. Yet, species living in more variable environments exhibited lower behavioral flexibility, likely due to energetic constrains in such habitats. Our standardized protocols provide opportunities for collaborative research, allowing increased sample sizes and replication, essential for moving forward in the field of comparative cognition. Follow-up studies could include more detailed measures of habitat structure and look at other potential selective drivers such as predation.
Collapse
Affiliation(s)
- Gilles De Meester
- Functional Morphology Lab, Department of Biology, University of Antwerp, Wilrijk, 2610, Belgium.,Section of Zoology and Marine Biology, Department of Biology, National and Kapodistrian University of Athens, Athens, 157 84, Greece
| | - Lisa Van Linden
- Functional Morphology Lab, Department of Biology, University of Antwerp, Wilrijk, 2610, Belgium
| | - Jonas Torfs
- Functional Morphology Lab, Department of Biology, University of Antwerp, Wilrijk, 2610, Belgium
| | - Panayiotis Pafilis
- Section of Zoology and Marine Biology, Department of Biology, National and Kapodistrian University of Athens, Athens, 157 84, Greece
| | - Emina Šunje
- Functional Morphology Lab, Department of Biology, University of Antwerp, Wilrijk, 2610, Belgium.,Department of Biology, Faculty of Natural Sciences, University of Sarajevo, Sarajevo, 71000, Bosnia and Herzegovina.,Herpetological Association in Bosnia and Herzegovina: BHHU: ATRA, Sarajevo, 71000, Bosnia and Herzegovina
| | - Dries Steenssens
- Functional Morphology Lab, Department of Biology, University of Antwerp, Wilrijk, 2610, Belgium
| | - Tea Zulčić
- Herpetological Association in Bosnia and Herzegovina: BHHU: ATRA, Sarajevo, 71000, Bosnia and Herzegovina
| | - Athanasios Sassalos
- Section of Zoology and Marine Biology, Department of Biology, National and Kapodistrian University of Athens, Athens, 157 84, Greece
| | - Raoul Van Damme
- Functional Morphology Lab, Department of Biology, University of Antwerp, Wilrijk, 2610, Belgium
| |
Collapse
|
3
|
Aiyer A, Shine R, Somaweera R, Bell T, Ward-Fear G. Shifts in the foraging tactics of crocodiles following invasion by toxic prey. Sci Rep 2022; 12:1267. [PMID: 35075144 PMCID: PMC8786828 DOI: 10.1038/s41598-021-03629-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2021] [Accepted: 11/15/2021] [Indexed: 11/09/2022] Open
Abstract
Biological invasions can modify the behaviour of vulnerable native species in subtle ways. For example, native predators may learn or evolve to reduce foraging in conditions (habitats, times of day) that expose them to a toxic invasive species. In tropical Australia, freshwater crocodiles (Crocodylus johnstoni) are often fatally poisoned when they ingest invasive cane toads (Rhinella marina). The risk may be greatest if toads are seized on land, where a predator cannot wash away the toxins before they are absorbed into its bloodstream. Hence, toad invasion might induce crocodiles to forage in aquatic habitats only, foregoing terrestrial hunting. To test this idea, we conducted standardised trials of bait presentation to free-ranging crocodiles in sites with and without invasive toads. As anticipated, crocodiles rapidly learned to avoid consuming toads, and shifted to almost exclusively aquatic foraging.
Collapse
Affiliation(s)
- Abhilasha Aiyer
- School of Life and Environmental Sciences, University of Sydney, Camperdown, NSW, 2006, Australia
| | - Richard Shine
- School of Biological Sciences, Macquarie University, North Ryde, NSW, 2109, Australia
| | - Ruchira Somaweera
- School of Biological Sciences, The University of Western Australia, Crawley, WA, 6009, Australia
| | - Tina Bell
- School of Life and Environmental Sciences, University of Sydney, Camperdown, NSW, 2006, Australia
| | - Georgia Ward-Fear
- School of Biological Sciences, Macquarie University, North Ryde, NSW, 2109, Australia.
| |
Collapse
|
4
|
Okamiya H, Inoue Y, Takai K, Crossland MR, Kishida O. Native frogs (
Rana pirica
) do not respond adaptively to alien toads (
Bufo japonicus formosus
) 100 years after introduction. Ecol Res 2021. [DOI: 10.1111/1440-1703.12259] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Affiliation(s)
- Hisanori Okamiya
- Department of Biological Sciences Graduate School of Sciences, Tokyo Metropolitan University Japan
| | - Yoshihiro Inoue
- Tomakomai Experimental Forest, Field Science Center for Northern Biosphere Hokkaido University Tomakomai Japan
| | - Kotaro Takai
- Tomakomai Experimental Forest, Field Science Center for Northern Biosphere Hokkaido University Tomakomai Japan
| | - Michael R. Crossland
- School of Life and Environmental Sciences The University of Sydney Sydney New South Wales Australia
| | - Osamu Kishida
- Tomakomai Experimental Forest, Field Science Center for Northern Biosphere Hokkaido University Tomakomai Japan
| |
Collapse
|