The maned wolf is undeniably an interesting animal; it’s the largest canid of South America, looks like a fox while being called a wolf, but is in reality neither a fox nor a wolf, and is the only member of its genus. The maned wolf is found in central and eastern South America, and monogamous pairs occupy  a territory of approximately 10 square miles, and due to their size, they remain protected from other carnivores surrounding them. The only animals that have been found to prey on the maned wolf are the puma and domestic dogs. Despite their size and omnivorous status, the number of maned wolves is rapidly declining, with less than 5,000 believed to live outside of Brazil. The main cause for the rapid decline of this animal is human interaction (The Smithsonian’s National Zoo and Conservation Biology Institute n.d.).

The maned wolf. Picture credit: The Smithsonian’s National Zoo and Conservation Biology Institute, 2020.

The maned wolf’s natural range in Brazil overlaps more with agricultural land than protected land, meaning these animals are surrounded by human activity as they go about their daily lives. The close interaction with people, as well as the expansion of agricultural land, puts the maned wolf at risk for elevated stress levels which could contribute to decreasing population numbers. When studying hormone levels from fecal samples, it was found that thyroid hormone levels were elevated in agricultural areas indicating better nutrition, progesterone levels decreased as maned wolves moved away from protecting lands, indicating a dropping level of reproductive success, and glucocorticoid levels increased as wolves moved into areas with more human activity, indicating elevated and prolonged stress. Despite the ease of finding food, the increased human activity is primarily negatively affecting the maned wolf (Vynne et al. 2014).

The heart rate of maned wolves in captivity has also been a subject researchers have been interested in recently. The maned wolf’s heart rate can drop as low as 30 beats per minute, but in moments of extreme stress their heart rate can increase to over 330 beats per minute. Researchers have been observing their reactions and heart rates in response to various activities and loud noises in order to better understand what activities specifically stress these wolves out (The Smithsonian’s National Zoo and Conservation Biology Institute, 2020). As habitat loss continues, the maned wolf is being forced to interact with humans, and gaining a better understanding of how human activity is impacting this unique animal will hopefully contribute to the continued conservation efforts.

References:

The Smithsonian’s National Zoo and Conservation Biology Institute. No date. The maned wolf. Retrieved April 24 2022 from https://nationalzoo.si.edu/animals/maned-wolf.

The Smithsonian’s National Zoo and Conservation Biology Institute. 2020. A Heart to Heart with Maned Wolves . Retrieved April 24 2022 from  https://nationalzoo.si.edu/conservation/news/heart-heart-maned-wolves.

Vynne, C., R. K. Booth, S. K. Wasser. 2014. Physiological implications of landscape use by free-ranging maned wolves (Chrysocyon brachyurus) in Brazil. Journal of Mammalogy 95: 696-706.

The eastern indigo snake (Photo 1), Drymarchon couperi, is a large, nonvenomous snake native to southeastern coastal plain areas, most commonly in southeastern Georgia and peninsular Florida. The species was federally listed as threatened in 1978 and has been the focus of recent conservation efforts. These snakes are long-lived and reach sexual maturity relatively late at 3-4 years of age (Hyslop et al. 2012).

Photo 1: An eastern indigo snake in Florida; photo originally taken by Todd Pierson and made available via the Florida Museum: Florida Snake ID Guide. Link: https://www.floridamuseum.ufl.edu/florida-snake-id/snake/eastern-indigo-snake/

The eastern indigo snake has primarily been threatened by habitat fragmentation and degradation, as seen by the fact that the longleaf pine and wiregrass sandhills that these snakes reside in have faced an area decline of over 97% since European colonization (Hyslop et al. 2012). and Breininger et al. found that over 50% of known eastern indigo snake mortalities within their 2012 study were due to human activity along roadways. The eastern indigo snake’s size means it is rarely preyed upon, so roads and human activities are a common source of mortality for this species (Breininger et al. 2012).

Figure 1: The top figure shows the annual survivability of the eastern indigo snake in three different areas (conservation core, conservation near roadway, and suburb) and the bottom figure shows the probability of encountering an eastern indigo snake in the same three areas. Figure courtesy of Breininger et al., 2012.

Beyond the increase threat to the survival of this snake due to roadways, urbanization is causing the home range to become increasingly restricted. Their northern range had previously been limited in part due to their use of Gopher Tortoise burrows as a source of protection from weather events and predators or as a breeding and nesting site (Hyslop et al. 2012). In more recent years, increased urbanization has led to a decrease in habitat diversity and home range size. In response to habitat fragmentation, it is very common to see animals increase their home range size, however eastern indigo snakes have had the opposite reaction. The mean area used by this species has decreased and the reason behind the change is still unclear. The leading hypotheses are that the snakes in suburbs moved less because they were easily able to find prey, the snakes outside of the suburbs have purposefully decreased their range and altered behavior in order to avoid roadways, or that the eastern indigo’s ability to take over den sites and feed on a wide variety of prey has allowed the snake to occupy areas uninhabitable to other species (Breininger et al. 2011). The exact reasoning for the alterations in the eastern indigo snake’s behavior and home range may be unknown, but all current hypotheses have important conservation implications and work is continuing to be done to ensure the survival of this species.

References:

Breininger, D. R., M. J. Mazerolle, M. R. Bolt, M. L. Legare, J. H.Drese, and J. E. Hines, 2012. Habitat fragmentation effects on annual survival of the federally protected eastern indigo snake. Animal Conservation 15: 361-368.

Breininger, D. R., M. R. Bolt, M. L. Legare, J. H.Drese, and E. D. Stolen. 2011. Factors influencing home-range sizes of eastern indigo snakes in central Florida. Journal of Herpetology 45: 484-490.

Hyslop, N. L., D. J. Stevenson, J. N. Macy, L. D. Carlile, C. L. Jenkins, J. A. Hostetler, and M. K. Oli. 2012. Survival and population growth of a long-lived threatened snake species, Drymarchon couperi (Eastern Indigo Snake). Population Ecology 54: 145-156.

Pearson, T.,  2021. Eastern Indigo Snake. Florida Museum of Natural History. https://www.floridamuseum.ufl.edu/florida-snake-id/snake/eastern-indigo-snake/