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Seeing the Forest through the Trees: Considering Roost-Site Selection at Multiple Spatial Scales.

Jachowski DS, Rota CT, Dobony CA, Ford WM, Edwards JW - PLoS ONE (2016)

Bottom Line: At the landscape scale, bat roost-site selection was positively associated with northern mixed forest, increased slope, and greater distance from human development.At the stand scale, we observed subtle differences in roost site selection based on sex and season, but roost selection was generally positively associated with larger stands with a higher basal area, larger tree diameter, and a greater sugar maple (Acer saccharum) component.Collectively, our results highlight the importance of considering day roost needs simultaneously across multiple spatial scales.

View Article: PubMed Central - PubMed

Affiliation: Department of Forestry and Environmental Conservation, Clemson University, 258 Lehotsky Hall, Clemson, South Carolina, 29634-0310, United States of America.

ABSTRACT
Conservation of bat species is one of the most daunting wildlife conservation challenges in North America, requiring detailed knowledge about their ecology to guide conservation efforts. Outside of the hibernating season, bats in temperate forest environments spend their diurnal time in day-roosts. In addition to simple shelter, summer roost availability is as critical as maternity sites and maintaining social group contact. To date, a major focus of bat conservation has concentrated on conserving individual roost sites, with comparatively less focus on the role that broader habitat conditions contribute towards roost-site selection. We evaluated roost-site selection by a northern population of federally-endangered Indiana bats (Myotis sodalis) at Fort Drum Military Installation in New York, USA at three different spatial scales: landscape, forest stand, and individual tree level. During 2007-2011, we radiotracked 33 Indiana bats (10 males, 23 females) and located 348 roosting events in 116 unique roost trees. At the landscape scale, bat roost-site selection was positively associated with northern mixed forest, increased slope, and greater distance from human development. At the stand scale, we observed subtle differences in roost site selection based on sex and season, but roost selection was generally positively associated with larger stands with a higher basal area, larger tree diameter, and a greater sugar maple (Acer saccharum) component. We observed no distinct trends of roosts being near high-quality foraging areas of water and forest edges. At the tree scale, roosts were typically in American elm (Ulmus americana) or sugar maple of large diameter (>30 cm) of moderate decay with loose bark. Collectively, our results highlight the importance of considering day roost needs simultaneously across multiple spatial scales. Size and decay class of individual roosts are key ecological attributes for the Indiana bat, however, larger-scale stand structural components that are products of past and current land use interacting with environmental aspects such as landform also are important factors influencing roost-tree selection patterns.

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Predicted probability of roost tree selection for Indiana bats (Myotis sodalis) in Fort Drum, NY, USA between 2007–2011.In panel A), points indicate mean posterior probability of use and vertical lines represent the limits of 95% credible intervals. This panel assumes bats are faced with a choice of 4 potential roosts: one in Acer species (ACSP), one in Carya cordiformis (CACO), one in Ulmus americana (ULAM), and one that is any other possible tree species (Other). In panel B), points indicate mean posterior probability of use and vertical lines represent the limits of 95% credible intervals. This panel assumes bats are faced with 7 potential roosts, classified from decay class 1 (DC1) through decay class 7 or 8 (DC78). In panel C), the solid line indicates the mean posterior probability of use and gray ribbons represent the limits of 95% credible intervals. This panel assumes bats are faced with a choice of 2 potential roosts: one fixed at the observed mean diameter at breast height (DBH, vertical dashed line) and the other represented by the value of the x-axis. All other variables are assumed constant in all panels.
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pone.0150011.g005: Predicted probability of roost tree selection for Indiana bats (Myotis sodalis) in Fort Drum, NY, USA between 2007–2011.In panel A), points indicate mean posterior probability of use and vertical lines represent the limits of 95% credible intervals. This panel assumes bats are faced with a choice of 4 potential roosts: one in Acer species (ACSP), one in Carya cordiformis (CACO), one in Ulmus americana (ULAM), and one that is any other possible tree species (Other). In panel B), points indicate mean posterior probability of use and vertical lines represent the limits of 95% credible intervals. This panel assumes bats are faced with 7 potential roosts, classified from decay class 1 (DC1) through decay class 7 or 8 (DC78). In panel C), the solid line indicates the mean posterior probability of use and gray ribbons represent the limits of 95% credible intervals. This panel assumes bats are faced with a choice of 2 potential roosts: one fixed at the observed mean diameter at breast height (DBH, vertical dashed line) and the other represented by the value of the x-axis. All other variables are assumed constant in all panels.

Mentions: The top-ranked tree-level model suggested each individual-level slope coefficient was reasonably represented by a constant mean across sexes and seasons (Table 3). We found bats were most likely to select roosts in American elm (Fig 5A); to avoid roosts in trees classified with decay class 1 and to select roosts in classified as decay class 4 (Fig 5B); and to select roosts in trees with large DBH (Fig 5C). Despite 82 of 116 roost trees being either dominant or co-dominant in crown position, we found no discernable population-level influence from crown position on roost-tree selection (i.e., 95% credible intervals of all elements of θl overlapped 0 for each of these variables).


Seeing the Forest through the Trees: Considering Roost-Site Selection at Multiple Spatial Scales.

Jachowski DS, Rota CT, Dobony CA, Ford WM, Edwards JW - PLoS ONE (2016)

Predicted probability of roost tree selection for Indiana bats (Myotis sodalis) in Fort Drum, NY, USA between 2007–2011.In panel A), points indicate mean posterior probability of use and vertical lines represent the limits of 95% credible intervals. This panel assumes bats are faced with a choice of 4 potential roosts: one in Acer species (ACSP), one in Carya cordiformis (CACO), one in Ulmus americana (ULAM), and one that is any other possible tree species (Other). In panel B), points indicate mean posterior probability of use and vertical lines represent the limits of 95% credible intervals. This panel assumes bats are faced with 7 potential roosts, classified from decay class 1 (DC1) through decay class 7 or 8 (DC78). In panel C), the solid line indicates the mean posterior probability of use and gray ribbons represent the limits of 95% credible intervals. This panel assumes bats are faced with a choice of 2 potential roosts: one fixed at the observed mean diameter at breast height (DBH, vertical dashed line) and the other represented by the value of the x-axis. All other variables are assumed constant in all panels.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4814100&req=5

pone.0150011.g005: Predicted probability of roost tree selection for Indiana bats (Myotis sodalis) in Fort Drum, NY, USA between 2007–2011.In panel A), points indicate mean posterior probability of use and vertical lines represent the limits of 95% credible intervals. This panel assumes bats are faced with a choice of 4 potential roosts: one in Acer species (ACSP), one in Carya cordiformis (CACO), one in Ulmus americana (ULAM), and one that is any other possible tree species (Other). In panel B), points indicate mean posterior probability of use and vertical lines represent the limits of 95% credible intervals. This panel assumes bats are faced with 7 potential roosts, classified from decay class 1 (DC1) through decay class 7 or 8 (DC78). In panel C), the solid line indicates the mean posterior probability of use and gray ribbons represent the limits of 95% credible intervals. This panel assumes bats are faced with a choice of 2 potential roosts: one fixed at the observed mean diameter at breast height (DBH, vertical dashed line) and the other represented by the value of the x-axis. All other variables are assumed constant in all panels.
Mentions: The top-ranked tree-level model suggested each individual-level slope coefficient was reasonably represented by a constant mean across sexes and seasons (Table 3). We found bats were most likely to select roosts in American elm (Fig 5A); to avoid roosts in trees classified with decay class 1 and to select roosts in classified as decay class 4 (Fig 5B); and to select roosts in trees with large DBH (Fig 5C). Despite 82 of 116 roost trees being either dominant or co-dominant in crown position, we found no discernable population-level influence from crown position on roost-tree selection (i.e., 95% credible intervals of all elements of θl overlapped 0 for each of these variables).

Bottom Line: At the landscape scale, bat roost-site selection was positively associated with northern mixed forest, increased slope, and greater distance from human development.At the stand scale, we observed subtle differences in roost site selection based on sex and season, but roost selection was generally positively associated with larger stands with a higher basal area, larger tree diameter, and a greater sugar maple (Acer saccharum) component.Collectively, our results highlight the importance of considering day roost needs simultaneously across multiple spatial scales.

View Article: PubMed Central - PubMed

Affiliation: Department of Forestry and Environmental Conservation, Clemson University, 258 Lehotsky Hall, Clemson, South Carolina, 29634-0310, United States of America.

ABSTRACT
Conservation of bat species is one of the most daunting wildlife conservation challenges in North America, requiring detailed knowledge about their ecology to guide conservation efforts. Outside of the hibernating season, bats in temperate forest environments spend their diurnal time in day-roosts. In addition to simple shelter, summer roost availability is as critical as maternity sites and maintaining social group contact. To date, a major focus of bat conservation has concentrated on conserving individual roost sites, with comparatively less focus on the role that broader habitat conditions contribute towards roost-site selection. We evaluated roost-site selection by a northern population of federally-endangered Indiana bats (Myotis sodalis) at Fort Drum Military Installation in New York, USA at three different spatial scales: landscape, forest stand, and individual tree level. During 2007-2011, we radiotracked 33 Indiana bats (10 males, 23 females) and located 348 roosting events in 116 unique roost trees. At the landscape scale, bat roost-site selection was positively associated with northern mixed forest, increased slope, and greater distance from human development. At the stand scale, we observed subtle differences in roost site selection based on sex and season, but roost selection was generally positively associated with larger stands with a higher basal area, larger tree diameter, and a greater sugar maple (Acer saccharum) component. We observed no distinct trends of roosts being near high-quality foraging areas of water and forest edges. At the tree scale, roosts were typically in American elm (Ulmus americana) or sugar maple of large diameter (>30 cm) of moderate decay with loose bark. Collectively, our results highlight the importance of considering day roost needs simultaneously across multiple spatial scales. Size and decay class of individual roosts are key ecological attributes for the Indiana bat, however, larger-scale stand structural components that are products of past and current land use interacting with environmental aspects such as landform also are important factors influencing roost-tree selection patterns.

Show MeSH
Related in: MedlinePlus