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Eastern Hellbenders
Where are they found, and can conservation save them?
Introduction
The Eastern Hellbender (cryptobranchus alleganiensis) is the only species of giant salamander outside of East Asia, native to crisp mountain streams in Appalachia. It is by far the largest amphibian in the United States, and has been around for tens of millions of years. Unfortunately, that might change. Hellbenders are dying off at an alarming rate, and due to degrading water quality and destruction of their habitats, hellbenders may become extinct before most people have ever heard of them. With this project, I wanted to first get an idea of where these salamanders are concentrated, because their elusiveness makes it difficult to track their conservation status. Next, I wanted to find out if there is a solid relationship between hellbender sightings and public protected lands, to see if that is the answer to restoring their habitats and rebounding their numbers.
Map 1: Hellbenders per Watershed
Using observation data from crowd-sourced wildlife data service iNaturalist and medium-sized drainage basin boundaries, this map shows which watersheds likely have the largest populations of hellbenders. Click on a watershed polygon to find out its name and how many hellbenders have been observed in its rivers and streams.
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This table shows every watershed with more than 2 hellbender sightings. The French Broad-Holston watershed clearly has the highest number by far, followed by the Allegheny, for which the hellbender is named in Latin.
Map 2: Hellbenders and Parks
To find out if hellbenders are more commonly found in streams belonging to protected lands, I plotted the observation data over a layer of all parks in the hellbender range. The green dots are hellbenders found on or within 1 mile of parks (to account for inaccurate coordinates), while the red dots are sightings outside of park lands.
131 out of 237 (a little over 55%) of all sightings in this data set were in or around a publicly managed park.
The cluster of sightings around the Great Smoky Mountains in the South seem to be mostly within park lands, whereas the northern cluster in Pennsylvania and New York is mostly outside of the parks.
Conclusion
What can we make of this data?
There are two main takeaways from this project: Hellbenders are likely heavily concentrated into a few specific watersheds, and they are disproportionately found on preserved park lands.
The French Broad-Holston and surrounding waters in the Southern Appalachian mountains, as well as the Allegheny drainage basin in Pennsylvania, seem to hold the vast majority of hellbender populations. The characteristics of streams in these watersheds can be studied to better understand what kind of habitats best suit hellbenders.
Although 55% is an underwhelming majority of hellbenders found in parks, it is notable considering the relatively sparse proportion of park land in the hellbender's wider range, which encompasses all of the greater Appalachian region. The actual reasons for this correlation could vary, from users of iNaturalist favoring parks to collect data, to ideal hellbender habitats coinciding with preserved lands, to the heightened biodiversity of protected lands in general. All things considered, it is safe to say that conserving land and the streams that run through it are a safe bet at protecting not just the hellbender, but any threatened species that call them home.