- Countryside Proprietary Homepage Countryside Proprietary, a Northern Virginia homeowner’s association, owns and maintains Horespen Run Nature Preserve.
- Horepen Run Bird Atlas Follow this link for a list of all of the birds found in Horespen Run Nature Preserve.
- Horsepen Run mentioned by Loudoun Wildlife Conservancy The Loudoun Wildlife Conservancy takes great interest in Horespen Run Nature Preserve and the many plants and animals that live here.
- Virginia Herpetological Society This site contains information about the location, appearance, and habits of each amphibian and reptile known to live in Virginia. The site includes forms for reporting observations of reptiles and amphibians. The site gives special attention to reported box turtle sightings.
- Virginia Native Plant Society This society is devoted to educating people about plants native to Virginia and preserving those plants for the benefit of future generations. Especially useful is the site’s list of reference websites, found under the Resources tab.
- The American Chestnut Foundation This organization works to bring back the nearly-disappeared American Chestnut, once an important part of our local economy. Look hard and you just might find a chestnut in Horsepen Run Nature Preserve.
- Save the Frogs! We love our amphibians at Horsepen Run Nature Preserve, and the folks at Save the Frogs! love amphibians around the world. Hop over to this site for information about how you can help Save the Frogs?