Aubrey Motsinger
Endangered species conservation has seen success in following a relatively consistent and straightforward process up to this point; breed individuals in captivity, restore their habitat, release them, and monitor the population as it recovers. But that might not be enough anymore. Some habitats have been degraded beyond restoration from climate change and urbanization while others were invaded by non-native species. So what can be done?
Roughly half of all species worldwide are on the move, including non-migratory ones. Such a redistribution of species not only impacts the environments taking them in but also those losing them. For instance, fish swimming to colder waters reduces food supply through the food chain, forcing predators to relocate with their prey or perish. The warming temperatures driving fish from their native locations are also affecting the life cycles of migratory species. With reliable seasonal cues, animals’ journeys have aligned with resource availability. However, the golden leaves and rain are now falling at different times and intensities, causing flora and fauna to mistime their interactions. The warming climate is also shifting habitats northward and to higher altitudes, necessitating permanent migrations for numerous species. This blanket statement mistakenly allows more area than is fit for a species by not considering their dispersal limits. Said limits include a species’ physical mobility and the terrain they must cross, likely lowering the suitability of any new habitats. Therefore, determining where species can live must consider whether they can reach those locations quickly enough, given the shrinking timelines. If the species is physically unable to reach the new habitat before it is no longer suitable, it was never actually a possibility. Fortunately, technological advances are making it easier to identify potential barriers that could hinder mobility. A new modeling tool–the MegaDSM–accounts for dispersal limits to then generate more accurate maps of species’ movements. These maps are then compared with others of a given area to recognize hazards to migration, like dried-up stream beds or housing developments. Conservationists can then work to clear the migration corridors and aid the animals’ travels.
An open pathway doesn’t automatically mean a traveled one. Some species lack migratory instincts and will likely never move. For others, corridors simply don’t exist. Those living on islands have nowhere to go as non-native species invade their habitats. The future of these species now lies in either completely removing the invasives or adapting to survive alongside them. Seeking to help, conservationists across the Pacific are employing a new and remarkably odd tactic; throwing things out of helicopters.
Hawai’i has witnessed many native species going extinct over the years, notably among its endemic honeycreeper populations. These birds once thrived with over 50 species but now only 17 remain and several face extinction. In a desperate effort to preserve the avian diversity important to both the island’s ecosystem and people, some honeycreepers have been brought into captivity. This has unfortunately trapped the birds indoors. Mosquitoes and the avian malaria they carry wait outside, capable of decimating bird populations within recently restored forests. These insects have only recently infiltrated the islands, but the native birds lack a natural immunity to the diseases they transmit and die after a single bite. Mosquitoes are contributing to a global rise in diseases as climates warm and make once inhospitable habitats available to them. Particularly on the island of Maui, they are chasing honeycreepers further up Haleakala and reducing the birds’ habitat. To combat the invasive insects, conservationists have begun employing a new tactic that has been effective elsewhere in the world; adding infertile male mosquitoes to the environment. This will reduce mosquito populations through regular, continued release, but the primary goal isn’t to completely rid the islands of mosquitoes. Rather, the purpose is to buy the birds enough time to adapt to their changing environment and develop an immunity to malaria.
Further west of Maui lies the island of Guam, which is suffering under an invasive species of its own. Numbering over 2 million, the brown tree snake population has wiped out most of the island’s native bird population. If they were to stow away on a plane heading to another island, they would similarly decimate those ecosystems and economies. To prevent this, dead mice are being laced with acetaminophen and dropped onto the treetops of the U.S. territory. This distribution method makes the drugged rodents less accessible to non-target species, although the 80mg dosage within wouldn’t be lethal if other animals ate them. This effort by the United States government has proven to be effective in reducing the population of brown tree snakes, but they will need permission from the local community before expanding the drop zones past military property.
Species purposefully introduced to an area still cause unconsidered harm to native ecosystems. Initially brought in by the Australian government to control pests among sugarcane plantations, cane toads instead became pests in the local environment. Particularly hurt by the toad’s invasion is the northern quoll. Unlike the endemic marsupial’s typical prey, cane toads produce poison when threatened. Northern quolls often die because the volume of poison produced is proportional to the amphibian’s size. However, if a northern quoll attacks a smaller toad, becomes sick afterward, but lives, the individual will avoid the amphibian in the future. Conservationists are using this to their advantage and conditioning the small marsupials to avoid the cane toads by dropping toad leg sausages laced with a nauseating drug from helicopters. When ingested, the sausages will produce a similar effect to that of eating a small cane toad. These amphibious deli deliveries target adult females with young. The marsupials learn hunting behavior socially, so adolescents will come to avoid the toads either through personal experience with the sausages or by watching their mothers–who themselves have eaten the sausages. Once enough individuals in one area develop an aversion toward cane toads, some will be dispersed among other habitats to help those individuals adapt more quickly and reduce the toad’s toll on the species.
We can’t un-change the climate, so we must help species change with it. New technology and creative techniques are crucial to the success of modern conservation efforts. And even if extinctions still occur, it would be more tragic if we didn’t try everything to stop them.
Citations
Borja, J. (2017, November 15). USDA poised to increase dropping of drugged mice to kill snakes. Pacific Daily News. https://www.guampdn.com/news/local/usda-poised-to-increase-dropping-of-drugged-mice-to-kill-snakes/html_195c4c7c-b229-5121-a769-eac6c5c5ae51.html
Dawson, C. (2022, September 8). In a warmer world, half of all species are on the move. Where are they going? USC Viterbi | School of Engineering. https://viterbischool.usc.edu/news/2022/09/in-a-warmer-world-half-of-all-species-are-on-the-move-where-are-they-going/
Geldard, R. (2023, October 5). Here’s how extreme weather is affecting animal migration. World Economic Forum. https://www.weforum.org/agenda/2023/10/climate-crisis-impacting-animal-migration/
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Halnon, E. (2021, May 19). Scientists are mapping animal migration to improve conservation. World Economic Forum. https://www.weforum.org/agenda/2021/05/scientists-are-mapping-animal-migration-to-improve-conservation/
Hausheer, J. E. (2022, September 18). Can helicopter-deployed toad sausages save Australia’s northern Quoll? (By The Nature Conservancy). Cool Green Science. https://blog.nature.org/2015/11/09/can-helicopter-deployed-toad-sausages-save-australias-northern-quoll/
How millions of mosquitoes could save Hawaii’s endangered birds (E. Kwong, Interviewer). (2024, June 17). In NPR. National Public Radio. https://www.npr.org/transcripts/1198910271
International Union for Conservation of Nature and Natural Resources [IUCN]. (n.d.). Wildlife in a changing climate. IUCN. Retrieved September 17, 2024, from https://iucn.org/story/202211/wildlife-changing-climate
Memmott, M. (2013, February 22). Dead mice are going to be dropped on Guam from helicopters (Really). NPR. https://www.npr.org/sections/thetwo-way/2013/02/22/172695707/dead-mice-are-going-to-be-dropped-on-guam-from-helicopters-really