Factors influencing ruffed grouse productivity and chick survival in West Virginia

I examined productivity, chick mortality, and factors influencing ruffed grouse (Bonasa umbellus) chick survival in West Virginia during 1998--1999. The proportion of hens that attempted to nest, hen success, average clutch size, and hatch dates were similar between age classes, between sites, and between years. Hatch dates were similar between age classes and between sites. Depredation was the major cause of nest failure. I examined 2 types of radio transmitter attachment methods (glue-on and collar type) to determine mortality and survival in ≤3-day-old grouse chicks. Glue-on transmitters performed poorly, whereas collar types had excellent retention time. Chick survival was low (\u3c30%) within the first 5 weeks post-hatch for both years. Most mortality was attributed to avian and mammalian predation. I examined arthropod abundance, biomass, and family richness, and concluded that these measures were not limiting in ruffed grouse chick survival

Necklace-Type Transmitter Attachment Method for Ruffed Grouse Chicks

Although methodologies to obtain cause-specific mortality and survival information for adult ruffed grouse (Bonasa umbellus) are well documented, procedures for determining similar parameters are lacking for grouse chicks. Mortality among grouse chicks is believed highest during the first few weeks posthatch. During 1999-2002, we equipped ruffed grouse chicks (n = 97) from 33 separate broods, ≤ 4-days-old with radio transmitters to assess the efficacy of transmitters and to examine survival/mortality. Further, we observed that grouse chicks retained transmitters (100%) until recapture or mortality. Handling time was limited because transmitter attachment took only a few minutes per brood. We observed mortality fates for 91% of radio-collared chicks. Therefore, because of the non-intrusive nature, field application, and retention of necklace-style transmitters employed in this study, this method may provide a desirable alternative to assessing survival/mortality among ruffed grouse chicks

Seeing The Forest Through The Trees: Considering Roost-Site Selection At Multiple Spatial Scales

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 (\u3e30 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

Observed Resiliency of Little Brown Myotis to Long-Term White-Nose Syndrome Exposure

White-nose syndrome (WNS) is a disease that has killed millions of bats in eastern North America and has steadily been spreading across the continent. Little brown myotis Myotis lucifugus populations have experienced extensive declines; however, some localized populations have remained resilient, with bats surviving multiple years past initial WNS exposure. These persistent populations may be critical to species recovery, and understanding mechanisms leading to this long-term survival and persistence may provide insight into overall bat and disease management. We monitored a maternity colony of little brown myotis on Fort Drum Military Installation in northern New York between 2006 and 2017 to determine basic demographic parameters and find evidence of what may be leading to resiliency and persistence at this site. Total colony size declined by approximately 88% from 2008 to 2010 due primarily to impacts of WNS. Counts of all adults returning to the colony stabilized during 2010–2014 (mean = 94, range 84–101) and increased after 2014 (mean = 132, range = 108–166). We captured 727 little brown myotis (575 females, 152 males) and banded 534 individuals (389 females, 145 males) at the colony. The majority of sampled bats showed evidence of recent past WNS infection and exposure to Pseudogymnoascus destructans, and we documented pervasive presence and limited viability of the fungus within the colony\u27s main roosting structure. We recaptured 98 individually marked females in years after initial banding, and some individuals survived at least 6 y. Ninety-one percent of all adult females, 93% of recaptured bats, and 90% of 1-y-old females (i.e., bats recaptured the first year after initial capture as juveniles) showed evidence of reproduction during the monitoring period. Using mark–recapture models, we estimated annual survival rates of juvenile and adult little brown myotis during 2009–2016 and examined whether reproductive condition or evidence of recent infection of WNS had any effect on survival. Annual survival r

Predicted probability of selecting a roost as a function of <i>Acer saccharum</i> importance value for male and female Indiana bats (<i>Myotis sodalis</i>) in summer and fall months in Fort Drum, NY, USA between 2007–2011.

<p>Solid lines indicate mean posterior probability of use and gray ribbons represent the limits of 95% credible intervals. Each panel assumes bats are faced with a choice of 2 potential roosts: one fixed at the observed mean <i>Acer saccharum</i> importance value (vertical dashed line) and the other represented by the value of the <i>x</i>-axis. All other variables are assumed constant.</p

Predicted probability of selecting a roost as a function of habitat classification for male and female Indiana bats (<i>Myotis sodalis</i>) in summer and fall months in Fort Drum, NY, USA between 2007–2011.

<p>Points indicate mean posterior probability of use and vertical lines represent the limits of 95% credible intervals. This Fig assumes bats are faced with a choice of 4 potential roosts, one in each habitat classification. All other variables are assumed constant across habitat classifications.</p

Predicted probability of roost tree selection for Indiana bats (<i>Myotis sodalis</i>) in Fort Drum, NY, USA between 2007–2011.

<p>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 <i>Acer</i> species (ACSP), one in <i>Carya cordiformis</i> (CACO), one in <i>Ulmus americana</i> (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 <i>x</i>-axis. All other variables are assumed constant in all panels.</p

Diagram illustrating 3 scales of investigation (landscape, stand, and roost tree) in Indiana bat roost-site selection at Fort Drum Military Installation, New York, USA between 2007–2011 and habitat covariates evaluated at each scale.

<p>At the landscape and stand scales, we identified used sites that were paired with 5 available points (square points) for resource selection analysis. Panel A illustrates the location of used roost sites for Indiana bat 150–282 (solid points) along with a 1976-m radius buffer (dashed line) used to define availability surrounding each roost site. The Fort Drum Installation boundary is depicted by solid black line. Panel B illustrates the location of all roost sites (solid points) and forest stands for which stand attribute data were collected are in gray. Roost-site selection at the tree scale (Panel C) was evaluated based on all available trees within a 0.0405-ha plot centered on the used roost tree.</p