Monday, February 29, 2016

Yellow-bellied Sapsuckers & Tree Damage

The yellow-bellied sapsucker (Sphyrapicus varius), also referred to as the red-throated, squealing, and whining sapsucker (McAtee 1911), is a species of woodpecker found across eastern North America. This migratory species breeds in the hardwood and coniferous forests of Canada, the upper Midwest, and the northeastern United States. In winter, yellow-bellied sapsuckers reside in the southeastern United States, Mexico and Central America, and the Caribbean.

Yellow-bellied Sapsucker (from Audubon)

Sapsuckers are known for their distinct feeding behavior: Excavating rows of holes in trees to feed on sap, cambium, and the insects attracted to these wells. Twenty to 100% of a sapsucker’s diet might be the sap itself, depending on the season (Varner et al 2006), and analysis of stomach contents suggest that the cambium itself may make up around 17% the sapsuckers diet (McAtee 1911). Observational data also shows that sapsuckers also rely heavily on these wells for insects for both adults and their young. After their young fledge the nest, adult sapsuckers will spend about 1 to 2 weeks teaching their young the art of sapsucking (Ehrlich et al 1988, p348).

While the sapsuckers’ work serves to feed them and their offspring, a “suite of animals” usurps these wells to feed on the sap themselves (Eberhardt 2000), including small mammals and other bird species (Varner et al. 2006). Ehrlich et al. (1988) notes that sapsuckers often guard their wells from both mammalian and avian thieves, particularly the ruby-throated hummingbird.

Moreover, there is method to the placement of these sap wells. According to Varner et al. (2006), yellow-bellied sapsuckers in their winter range tend to create wells on the north aspect of tree trunks of larger diameter trees. In addition, some research suggests that sapsuckers choose older, diseased trees within which to excavate wells, perhaps because of the increased amino acid content in the sap of weakened trees (Eberhardt 2000).

Sapsuckers have been documented to feed from at least 252 species of native trees and vines, and 31 species of non-native trees (Atwell 1911, p53). Mortality attributed to sapsucker damage has been documented among more than 10% of these species (Atwell 1911). In their breeding range, where sapsuckers feed on trees from April until October, tree mortality associated with sapsucker damage may only be 1 to 3% for some species (e.g., hemlock, red spruce), but can reach up to 40 to 67% for thin barked trees (e.g., red maple, paper birch, and gray birch) (Rushmore 1969). According to Atwell (1911), only tree species in the Mulberry family (Moraceae), such as mulberries and Osage orange, have no documented yellow-bellied sapsucker feeding activity.

The feeding behavior of sapsuckers can girdle and kill trees. The sapsuckers drill through the outer bark of the tree, past the bast (i.e., inner bark), into the cambium, sometimes penetrating the wood (McAtee 1911). This means, that a sapsucker – to access the sap of the tree – is actually puncturing the vascular tissues of the tree. The sapsucker is puncturing those straw-like vessels that move food and water, stopping some parts of the tree from receiving adequate water and nutrients.

Sapsucker damage can also provide entrĂ©e for pathogens and insects, making trees more susceptible to fungus in particular. For example, when the fungus Peridermium cerebrum infects a tree through sapsucker holes, it results in large knots protruding from the bark (McAtee 1911). In contrast, some trees will attempt to heal the wounds and grow thicker at the site of the sapsucker damage, resulting in “shelf-like” layers of woody growth (McAtee 1911, p19). This shelving is particularly pronounced in shagbark hickory (Carya ovata) (pers. obs., 10 Feb 2016).

Sometimes the damage done by sapsuckers can extend into the wood itself, leaving the wood “distorted and discolored in such a way as to destroy its commercial value” (McAtee 1911, p19). Anecdotal evidence has suggested that sapsuckers can affect commercial enterprises in other ways, including damage to apple and peach orchards, maples used for syrup production, and timber producing pines (McAtee 1911).

While the most noticeable sapsucker damage is on trees, woody vines may also sustain damage, including grape species (Vitus), Virginia creeper, and trumpet creeper. The news isn’t all bad: Poison Ivy is also affected.

Eberhardt, L. S. 2000. Use and selection of sap trees by yellow-bellied sapsuckers. The Auk 117(1): 41-51.

Ehrlich, P., D. Dobkin, and D. Wheye. 1988. The Birder's Handbook. New York: Simon & Schuster.

McAtee, W. L. 1911. Woodpeckers in relation to trees and wood products. Washington D.C.: U.S. Department of Agriculture, Biological Survey no. 39: September 26, 1911.

Rushmore, F. 1969. Sapsucker: Damage Varies with Tree Species and Seasons. USDA Northeastern Forest Experiment Station, Upper Darby, PA. USDA Forest Service Research Paper NE-136.

Varner, J. M., J. S. Kush, and R. S. Meldahl. 2006. Characteristics of sap trees used by overwintering Sphyrapicus varius (Yellow-Bellied Sapsuckers) in an old-growth pine forest. Southeastern Naturalist 5(1): 127-134.

Monday, February 15, 2016

Coyotes in North Carolina

Reports of coyotes (Canus latrans) in North Carolina first emerged in the 1930s, often associated with imported specimens intended to help hunters practice for better game, i.e., red fox. Not until 1947, on Cherokee land in Swain County, did a forest ranger make the first recorded wild sighting of a coyote. In the mid-1980s the range of coyotes in North Carolina was primarily confined to some counties on the western boundary of the Piedmont. Yet today, coyotes occur in all 100 counties of the state. Their populations remain highest in the Western counties, but in the last ten to twenty years sizeable populations have grown in the Coastal Plain.

It isn’t difficult to account for recent increase in coyotes in North Carolina. The species is extremely mobile, with individuals dispersing up to 50 miles. Plus, coyotes can adapt to a wide-range of culinary delights. As a carnivore, most of a coyote’s diet is made up of small mammals, but they will also consume snakes, birds and large insects. If live food is scarce, coyotes will eat carrion. If carrion is scare, as it is in autumn and winter, they will eat berries and herbs. Fox hunters, houndsmen, and wildlife officials have unwittingly contributed to the rise of the coyote by releasing adults for training and accidentally introducing very cute coyote pups to gamelands instead of similar looking red fox pups. Moreover, the coyote’s natural predators in North Carolina have either been hunted to extinction (the gray wolf) or nearly so (the red wolf and mountain lion).

Coyotes from

Besides being adaptable, coyotes are also prolific. They reach sexual maturity around the age of one year, and by age two they select a mate for life. Coyotes will begin courtship rituals between January and March, and after a gestation of only 63 days a female will give birth to between one and twelve young (average litter: 6 pups). The pups wean from their mother six to eight weeks after being born, but continue to get food from their father and hunting lessons from their mother until the young disperse after one year.

The clever and cunning antics of coyotes often increase their success. They watch the sky for ravens, letting the birds guide them to carrion. They hunt as a pair, with one partner jumping wildly at a rabbit forcing it right into the mouth of its mate. Coyotes also adjust their behavior to gain from humans: begging in parking lots in Death Valley or attacking pets in the suburbs.

Although coyotes terrorize local neighborhoods, sometimes eat small dogs and chickens, and may carry rabies, they do confer one benefit: coyotes eat feral cats, and thus they could improve depleted song bird populations. Unfortunately, this benefit only further demonstrates the trouble we humans have respecting Mother Nature’s balance…and it doesn’t work out so well for those poor cats either.

Did you know?
·         Coyotes range from three to four feet long, and weight between 20 and 50 pounds.
·         Coyotes can communicate with over ten different sounds.
·         50% to 70% of coyotes die before attaining adulthood

·         Coyotes live between 10 and 14 years in the wild


Hampton, J. 1 Aug 2010. “Studies try to get handle on coyotes in N.C.” The Virginian-Pilot. Available at:

Hill, E. P., P. Sumner, and J. B. Wooding. 1987. Human influences on range expansion of coyotes in the southeast. Wildlife Society Bulletin 15:521-524.

Ware, J. 12 Nov 2007. “Coyotes make selves at home in our backyards.” StarNews Online. Available at: [accessed 02 Feb 2011]

Wilsdon, C. 1997. “Gaining Ground." National Geographic World. Feb 1997.

Saturday, February 6, 2016

Four-toed Salamander (Hemidactylium scutatum)

The four-toed salamander (Hemidactylium scutatum) is listed as a species of special concern in North Carolina. Although some populations have been found in the Coastal Plain and Mountains, the four-toed salamander predominantly occurs in the Piedmont where it prefers marshes, swamps and ephemeral ponds surrounded by forest.

After mating in the fall, some female four-toed salamanders cooperate with each other during the spring nesting season, preferring to lay eggs together on moss-covered logs and roots draped over still water. This communal nest allows one female to leave for a short period, while the other stays behind to tend to the eggs. While it may look like the females are guarding the eggs from predators, researchers have suggested that the females actually protect the eggs from being destroyed by fungus. Reid Harris and Douglas Gill have suggested that female four-toed salamanders may actually eat eggs on which fungus is detected. 

Four-toed salamander by J. D. Willson (

After one and half to two months of protection, in the warmth of early summer, the larvae finally emerge from the eggs and drop into the still water where they transform into small adults in about 6 weeks. It will take at least one and half more years for the young four-toed salamanders to reach sexual maturity. 

As adults, the four-toed salamander ranged from two to 3.5 inches. The back tends to be a mottled reddish brown with small black spots, with the tail getting progressively redder. The tail, when grabbed, can be disconnected and will continue to writher and wiggle to lure predators away from the fleeing salamander. The belly of the four-toed salamander is white with black spots, and as its name suggest, the four-toed salamander only has four toes on each hind foot. Adults can typically be found under rocks and leaf litter.