New England wildlife and rock walls: how do they share the forest?

Throughout the forests of New England, rock walls are commonly found (broken down as they may be) as remnants of past farm boundaries. Forest flora and fauna soon recolonised the fields after many of the farms were abandoned for alternate land in the western United States. Today, this occurrence can be witnessed in University of Rhode Island’s very own backyard: North Woods. We worked with Dr. Brian Gerber and his graduate students Juliana Masseloux and Erin Wampole to develop an independent research project to characterize the wildlife in the area and to understand how they are using the remnant rock walls scattered in the forest.

We explored the following questions: what mammals are in North Woods despite its proximity to a potentially disturbing campus and are/how are these mammals using the rock walls that may fragment their habitat?

White tailed deer crossing through a gap in a remnant rock wall, North Woods, Kingston, RI

White tailed deer crossing through a gap in a remnant rock wall, North Woods, Kingston, RI

A map of North Woods (Kingston, RI) showing the camera locations in green icons and the most adjacent remnant rock walls in yellow

A map of North Woods (Kingston, RI) showing the camera locations in green icons and the most adjacent remnant rock walls in yellow

To dive into these questions, we deployed ten trail cameras throughout North Woods that pointed at either 1) a stretch of solid rock wall, or 2) a gap in a rock wall with what appeared to be a game trail running through it. We compared the mammal species seen on the cameras to determine which animals preferentially used solid parts of the rock walls or gaps in the walls. The cameras recorded still photos at the sites for about 4 weeks. We checked each camera weekly and tagged pictures with information such as species, group size, whether the pictures were of a stretch of a solid rock wall or a trail through a rock wall, etc. Rather than using the number of individuals in our analysis, we analyzed the number of groups. This means that if there were four deer in one picture, we counted that as one group.

 

Our pictures revealed what we had initially hypothesized: more animals were using gaps in the walls to travel through rather than using the solid walls to travel on top of or over.

These animals may be too heavy to travel on top of the wall, or perhaps it takes too much energy to do so.

The mammals that tended to travel on the top of rock walls were more agile. This method of transportation could be used because there is less resistance traveling on top of the wall than on the forest floor.

human.JPG

URI student

admires the wall

Despite the study area’s proximity to the URI campus, many typical New England forest species were detected:

The number of times a group of animals was detected at our camera sites either placed at a gap in the wall (Trail, orange bars) or at a solid stretch of the wall (W, blue bars). The number of groups of animals was analyzed, not the number of individuals. This most likely led to some underestimates of the animals often found in groups of multiple individuals such as deer. The majority of animals recorded at gaps in the walls were passing through the gaps while the majority of animals captured at continuous rock walls were traveling on top of the walls. However, some individuals at both site types used the forest surrounding the rock wall for activities such as foraging or locomotion.

The number of times a group of animals was detected at our camera sites either placed at a gap in the wall (Trail, orange bars) or at a solid stretch of the wall (W, blue bars). The number of groups of animals was analyzed, not the number of individuals. This most likely led to some underestimates of the animals often found in groups of multiple individuals such as deer. The majority of animals recorded at gaps in the walls were passing through the gaps while the majority of animals captured at continuous rock walls were traveling on top of the walls. However, some individuals at both site types used the forest surrounding the rock wall for activities such as foraging or locomotion.

Future projects: We may use the group size instead of number of groups to more accurately estimate species abundance. Another aspect we would like to investigate during our next study period is how species are using each wall. Are they using it as a funnel, because the walls are too large to get around otherwise? Or are predators using them to hunt, and prey using them as hiding spots? The answers to these questions could give more insight into wildlife management. If the walls are prohibiting wildlife from moving around, or disrupting the food web at all, we should consider the possibility of their removal.

Jessica Burr  is an undergraduate student interning in  Dr. Brian Gerber’s lab  studying Wildlife and Conservation Biology at the University of Rhode Island.

Jessica Burr is an undergraduate student interning in Dr. Brian Gerber’s lab studying Wildlife and Conservation Biology at the University of Rhode Island.

Ruby Nguyen  is an undergraduate student interning in  Dr. Brian Gerber’s lab  at the University of Rhode Island double majoring in Biology and Wildlife Conservation Biology.

Ruby Nguyen is an undergraduate student interning in Dr. Brian Gerber’s lab at the University of Rhode Island double majoring in Biology and Wildlife Conservation Biology.

 
Erin Wampole  was Jessica and Ruby’s co-mentor for the North Woods camera trapping project. She is a Master’s student researching carnivore biology and applied ecology in  Dr. Brian Gerber’s lab .

Erin Wampole was Jessica and Ruby’s co-mentor for the North Woods camera trapping project. She is a Master’s student researching carnivore biology and applied ecology in Dr. Brian Gerber’s lab.

Juliana Masseloux  was Jessica and Ruby’s co-mentor for the North Woods camera trapping project. She is a Master’s student researching conservation in human-wildlife conflicted areas in  Dr. Brian Gerber’s lab .

Juliana Masseloux was Jessica and Ruby’s co-mentor for the North Woods camera trapping project. She is a Master’s student researching conservation in human-wildlife conflicted areas in Dr. Brian Gerber’s lab.