Assessing habitat suitability, species richness, and activity patterns of NJ bats

Abstract: Bats are keystone species that play a vital role in the health of ecosystems. Urbanization and the proliferation of white-nose syndrome (WNS), a fungal disease that targets hibernating bats, have drastically reduced many species’ numbers throughout North America. To properly understand and remedy how habitat fragmentation may threaten bats, it is crucial to first understand basic aspects of their biology, such as habitat use and patterns of activity. New Jersey is one of the most urbanized states in the country and is located near the epicenter of the WNS outbreak. Despite that, no current assessments of the effects of land use on habitat suitability for bats exist. Our aim is to determine which habitats in New Jersey are the most suitable for nine species of bats – the Big Brown Bat (Eptesicus fuscus), Silver-Haired Bat (Lasionycteris noctivagans), Eastern Red Bat (Lasiurus borealis), Hoary Bat (Lasiurus cinereus), Eastern Small-Footed Myotis (Myotis leibii), Little Brown Bat (Myotis lucifugus), Northern Long-Eared Bat (Myotis septentrionalis), Indiana Bat (Myotis sodalis), and Tri-Colored Bat (Perimyotis subflavus).

Our study will investigate the presence of bats in four different localities with varying levels of urbanization – Rutgers University-Newark (urban), the Meadowlands Environmental Research Institute (urban park), the Pine Barrens (pine forest), and the Allamuchy Mountain State Park (mixed hardwood forest). We will use Ecological Niche Models (ENM) to estimate predicted distributions and species richness across the state and will also measure activity (i.e. nightly, monthly, and overall) over time at each locality. We predict that urban environments will be the least suitable for the majority of species, urban parks will have intermediate suitability, and forested areas will have the highest overall suitability. We also anticipate an increase in bat activity during the warmest months (July and August 2021) and during peak foraging hours for many bats.

Methods: Ecological Niche Modeling—Since data for New Jersey bats are very limited, we collected bat occurrence records from for New Jersey, New York, Pennsylvania, Maryland, Connecticut, and Delaware, ensuring to remove records from additional states. Any records that did not provide latitude or longitude coordinates were georeferenced following MaNIS guidelines. We used the georeferenced points and climate data from to create Ecological Niche Models (ENM) for each species in Maxent v.3.4. The models will predict the climatic conditions that are the most optimal for each species of bat. Individual ENMs produced for each species will be used in a Stacked Species Distribution Modeling approach in the R package SSDM to model bat community assembly and “hotspots” of species richness across New Jersey.

Acoustic Bat Monitoring—From May 2021-October 2021, we will place stationary SongMeter SM2BAT+ (Wildlife Acoustics) ultrasonic, acoustic-recording detectors in each of the 4 localities — Rutgers University-Newark, the Meadowlands Environmental Research Institute (MERI), the Pine Barrens, and the Allamuchy Mountain State Park. The detectors will automatically be set to record bat activity during the first 10 nights of each month. We will analyze bat calls by using the latest version of Kaleidoscope Pro. Using the echolocation call data, we will be able to predict species richness and activity per species at each locality. Echolocation and ENM data will be combined to assess patterns of habitat suitability and species richness and diversity to improve our understanding of how bats use urban and forested landscapes, and identify “hotspots” of bat diversity in New Jersey.

Expected Results: Several studies have examined the relationship between urbanization and decreased bat biodiversity. Based on this research and our habitat suitability models, we predict that urban areas will have the lowest suitability for NJ bats, urban parks will have intermediate suitability, and forested areas will have the highest suitability. We anticipate detecting fewer calls from Little Brown Bats, Indiana Bats, Tri-Colored Bats, Northern Long-Eared Bats, and Eastern Small-Footed Myotis’ at all sites since these species have been greatly affected by white-nose syndrome and may still be rebounding. Due to their large body size, Big Brown Bats have been able to stave off white-nose syndrome more easily than smaller species. Big Brown Bats are also more commonly found in urban areas as opposed to forested ones, so we expect to record more calls at Rutgers University-Newark and MERI. Eastern Red Bats, Silver-Haired Bats, and Hoary Bats are mainly solitary in nature, so they have not been affected by white-nose syndrome. We expect these species to have the greatest overall abundances. Lastly, our results should show peak activity according to the different foraging bouts of different species (i.e. after sunset and before sunrise) and between the months of July and August.

Scientific Merit: Bats are keystone species in ecosystems and provide a variety of ecosystem services (i.e. natural insect pest control) that are in need of protection. Despite that, bats are often unjustifiably portrayed as vectors of disease or maligned by many people, especially in areas where human-wildlife interactions may occur. In order to understand how bat species are affected by urbanization, we must first understand the factors that are most favorable for them. If bat species richness and activity tend to concentrate in certain zones within urbanized areas, then we can better understand which protections need to be put in place to help stabilize their populations. The aim is for conservationists, ecologists, and urban planners to determine which habitats and conditions need to be maintained in order to promote bat biodiversity.