January Species Spotlight: North American Porcupine and Hydrilla

January 31, 2023

North American Porcupine, Erezithon dorsatum

The North American porcupine is one of New York State’s oddest looking mammals and one of the largest rodents on the continent. These prickly creatures can be found across a wide swath of North America, from Alaska to Mexico and California to Maine. They are found in an incredibly diverse array of habitats, from mixed forests of the Northeast to the tundra of Alaska and Canada, and arid desert shrubland of the American Southwest.

Porcupines are one of the largest rodents in America, second only to the Beaver. Adult porcupines measure ~25-40 inches in length and weigh around 10-20 lbs but have been known to reach up to 40 lbs! The upper portions of the porcupine’s body and tail are covered in an approximate 30,000 quills which each measure about 2-3 inches in length. Although they do not shoot quills at their predators (a common misconception), when threatened they will erect their quills (not unlike an angry cat) and use their muscular tail to lash out. The quills themselves are easily detached and may lodge into the skin of the predator. Natural muscle movement will gradually drawn the quills deeper at a rate of ~1mm per hour. Proof that, although adorable, porcupines are not to be trifled with!

The porcupine diet changes seasonally. In the spring and summer they subsist mostly on fresh vegetation like leaves, grasses and berries, but in the winter they rely on a diet of evergreen needles and the inner bark of trees. Their continuously growing teeth are perfectly suited for stripping the bark from trees in the winter. Porcupines rely on a specialized combination of gut microflora to digest cellulose and their gut takes up an impressive 75% of their body cavity! While porcupines may eat a wide variety of trees during the winter, they tend to consume the inner bark of only 1-2 tree species, researchers suggest that this may fine tune their gut microbiome, making digestion more efficient. Often, a porcupine will continue to target the same trees repeatedly, a habit which can result in permanent damage or death to the tree. It is this behavior that has branded them “nuisance wildlife” in many parts of the country, but often the damage inflicted by porcupines is significantly less than the damage inflicted by invasive diseases, fungi and insects. 

Given their winter diet, it should come as no surprise that porcupines are particularly skilled at climbing. Their roughened foot pads and curved claws mean that they are as at home in the trees as they are on the ground. They den in a variety of places like hollow trees, caves, under ledges and rocky crevices and even in abandoned buildings.

Mating occurs during the fall and early winter, and involves an elaborate courting ritual that includes dancing, singing and other less adorable practices. If successful, the female will gestate her young for 205-217 days, most often giving birth to a single porcupette in the spring or summer.

Keep an eye out for porcupines this winter and for more information, check out the resources below!

 

Hydrilla; Hydrilla verticillata

Hydrilla, colloquially referred to as water-thyme, is one of the most worrisome invasive plants in the country and was first discovered in the state in 2008 in Orange County. Native to Southeast Asia, hydrilla was commonly used as a decorative plant in home aquariums until its addition to the list of Federal and State Noxious Weeds prohibited its possession, trade or sale in New York state.

In the warmer months, this perennial aquatic herb grows at an incredible rate – up to an inch a day. Hydrilla will initially grow along the bottom of lakes, streams and rivers, as the weather warms it will anchor itself in the soil via the development of a tuber and stretch toward the surface creating a wall of vegetation. Once it reaches the surface, its prolific growth quickly results in the development of dense mats that displace and shade out native plants. Dense hydrilla growth has measurable negative impacts on fish spawning habitats and reduces naturally occurring food sources that are important for migratory waterfowl. Hydrilla also decreases the overall oxygen content of the water, leading to potential fish kills. These dense mats can also obstruct water flow through reservoirs,irrigation canals, water treatment plants and more.

In addition to the many negative ecological impacts of hydrilla, it also has the potential to impact local economies and tourism. Dense mats of the plant can make recreational boating, sportfishing and swimming impossible – and the reduction in native vegetation often results in diminished sizes of local sport fish like largemouth bass.

Hydrilla produces seeds, but may also bud from portions of the plant that overwinter, green buds called turions and from tubers which develop at the end of the roots. Portions of the plant are easily broken off and can be transported to new locations by boats and trailers, fishing equipment and natural currents!

Click here to learn more about hydrilla and how you can help prevent its spread by following a few simple steps and by reporting any suspected infestations by recording your location, taking a photo and uploading to IMapInvasives!

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Sources

Native; North American Porcupine

https://nationalzoo.si.edu/animals/north-american-porcupine

https://www.esf.edu/aec/adks/mammals/porcupine.htm

https://animaldiversity.org/accounts/Erethizon_dorsatum/

Invasive; Hydrilla

https://www.dec.ny.gov/animals/104790.html

https://nystateparks.blog/2018/07/08/invasive-species-spotlight-hydrilla/

https://nyis.info/invasive_species/hydrilla/