Agriculture and wildlife have never been mutually exclusive but rather can support the vitality of each other when managed properly. Management strategies employed by farmers over large parcels of land impact both on- and off-farm ecosystems and wildlife. Management strategies that benefit insectivorous wildlife may provide insect pest management. Bats are a widely underestimated biological tool for insect pest management and farmers are not sure how many bats they have or how to enhance their activity. The objective of this study was to assess bat populations and activities using acoustic monitoring equipment at sites under a variety of agricultural land uses and to identify tools to enhance bat activities for Integrated Pest Management. We began this investigation in May 2016. Bat activity was monitored in 10 farming systems from both conventional and organic managed farms and with tree lines and with out tree lines. The 10 sites were paired up to make it possible to monitor 2 sites (one pair) in one night with monitoring occurring May-September. In both organic and conventional systems, a tree line had a highly significant effect on bat passes (P < 0.0001). A trend was also observed in agricultural systems without a tree line whereby organic systems tended to record greater bat activity compared to conventional systems, even though the differences were not significant. The most common species found at all sites was the big brown bat (Eptesicus fuscus). This species readily occupies bat houses and structures like barns and has a diet primarily made up of agricultural pests. This study’s results support the use of tree lines in agricultural systems and the installation and maintenance of roosting sites to support big brown bats for pest management.
Outreach efforts were directed to the farming community and a conservative estimate shows we reached at least 500 farmers and 1200 agriculture service providers. Outreach included online webinars, farming magazine articles, local news articles, field days, and interactive presentations both on site and off site.
Next to weeds, insects are one of the biggest impediments in organic production, particularly organic vegetable production. Bats are an often overlooked form of biological insect management applicable to these systems. In the Northeast, these nocturnal insectivores consume large amounts of agricultural pests, such as weevils, beetles, and moths, in a single day. Agricultural landscapes encourage bat activities if they provide adequate areas for foraging, corridors for travel and protection, and roosting structures. However, some species of bats in the Northeast have seen huge population declines due to White-nose syndrome. This disease started in New York and has aggressively been decimating bat populations by infecting them during hibernation periods. White-nose syndrome has spread out across the U.S. expanding every year, but the Northeast has been affected the longest with the largest decreases in bat populations. With estimated loses of at least 6.7 million bats so far, it is speculated that pest pressures will rise in the coming years as bat numbers continue to dwindle. To combat increasing pests, conventional farmers will rely more heavily on insecticides causing more harm to other wildlife, human health, and water and soil resources. The services bats provide us are estimated to be from at least $3.7 billion to $53 billion in the US annually. Rather than using insecticides, organic farmers are seeking more tools for their toolboxes. Farmers have expressed an interest to us but admittedly lack the knowledge on how to better utilize bats.
The aim of this project was to combine previous research on bats’ occupancy and use of agricultural systems with results from this project to determine best practices for attracting bats, particularly since the introduction of White-nose syndrome has changed bat population dynamics. Determining how bats use land for foraging can help us plan agricultural landscapes to increase their presence, while understanding how they occupy roosting structures will help us identify tools for attracting bats and supporting their populations.
Past studies confirm that bat diets consist of particular agricultural pests. Those studies were reviewed to design this project which should improve understanding of bat presence and activity in agricultural landscapes to create an effective model for attracting bats and their use in IPM. Additional research recommended by this study will target the understudied relationships between bats and agriculture in the Northeast region. In addition, since the introduction of White-nose syndrome has changed bat population dynamics, it is crucial to reevaluate existing bat populations by species. Some bat species have been hit harder than others and new acoustical monitoring can give us a current idea of population dynamics by species to develop proper IPM practices. For example, Big brown bat populations have seen 50% decline as opposed to an over 90% decline seen in other species. Big brown bats are noted to provide a great service to agriculture with over 80% of their diets consisting of agricultural pests such as scarab beetles, spotted cucumber beetles, stink bugs, and leaf hoppers (Whitaker, 1995).
The goal of this study was to investigate current populations, develop plans to use bats to help farmers, in turn helping bats, and reduce insecticides. Pesticide reduction is critical to human and planetary health. For example, corn is an essential crop grown worldwide on over 150 million hectares and adding bats as an organic IPM measures in corn would have astounding positive effects. It is estimated that the suppression of herbivory by insectivorous bats is worth more than 1 billion USD globally on corn alone, and bats may further benefit farmers by indirectly suppressing pest-associated fungal growth and toxic compounds on corn (Maine, 2015). Connectivity of feeding patches and roosts are important for bat habitats as they avoid crossing open areas (Kunz, 2003) and riparian buffers are incorporated into many bat conservation plans (Lacki 2007). Measures like these protect our water and soil resources as well as protecting ourselves and wildlife from pesticides. A past study done at the Rodale Institute in 2008 by a Penn State student measured bat activity and insect abundance, but her project was limited to two sites. However, her study provided baseline data for insect and bat populations prior to White-nose syndrome fully affecting this region. Most importantly, results and experiences from this project will form the basis for providing education to farmers to help them use bats for organic insect pest management which has been poorly presented in the farming community. Outreach efforts will aid farmers in reducing pesticide use and increase bat populations in our region for us all to benefit from.
The first objective of this project was to investigate HOW bat populations and activities differ across landscapes and land uses. A better understanding of the relationships between land use and bat presence can help farmers attract bats and use their abilities for pest management freeing up time and money and reducing commodity losses and pollutants while supporting our native ecosystems.
The second objective was to provide crucial data as to WHAT our current bat populations in the region are while at the same time, determine WHERE bats forage more heavily and HOW to modify those areas to incorporate best practices.
Our third objective was to assess the effectiveness of artificial roosts in attracting and increasing bat populations on farms. Understanding the occupancy rates of different types of artificial roosts like bat boxes can provide a tool to support bat populations and attract them onto a farm.
Our final objective was to take existing studies and combine them with measurement from this project to create educational models, tools, and many outreach opportunities that will aid farmers in reducing pesticide use and increase bat populations in our region for us all to benefit from.
Monitoring Bat Activity:
A research project was established in May 2016 to determine bat populations and activity differences between different land use management systems. Acoustic monitoring equipment was used to collect data on bat activity and species diversity and compared these relative to landscape and land use. Direct comparisons were made between conventionally and organically managed systems at Rodale Institute and collaborating farms under similar landscape or land use (e.g. forested riparian buffers, orchards, cultivated grain, or vegetable fields). Bat activity was monitored in 10 conventionally and organically managed agricultural systems, with different landscape features (tree lines or no tree lines bordering the crop). We used stationary acoustic monitoring equipment set up on tripods at the study sites. Using both a Pettersson D500x and AR125 model acoustic monitoring device, the ultrasonic echolocation calls of bats were recorded on a triggered recording setting. Recorded data was then interpreted into viable bat calls using Sonobat software. These viable calls recorded as individual sound files, referred to in this study as bat passes, were then quantified as bat activity. Each bat call represented one bat pass over the range of the microphone of the Pettersson D500x or AR125. The bat monitoring equipment microphones record clear calls from most common species within a 30-50 m. range. The Sonobat software also analyzed the bat calls to determine bat species. We looked at whether bats were just passing by in flight or foraging to determine whether they were using the specific landscapes for traveling or foraging. Through physical observation of bat behavior coupled with the presence of feeding buzzes during recording, bat passes were attributed to bat foraging activity. Bat passes represented a measure of bat activity.
The 10 sites were paired up to make it possible to monitor 2 sites in one night. This translated into 5 pairs at every site for a total of 10 nights of monitoring representing a replicate. A total of 5 replicates were completed during the season (May-September). The 10 agricultural systems from which data on bat activity was collected included the following:
Organic apple orchard with no tree line (ORG Apple NT)
Organic apple orchard with tree line (ORG Apple T);
Conventional mixed fruit orchard with no tree line (CNV Apple NT) ;
Organic grain crop (corn and soybean) with tree line (ORG Grain T);
Organic grain crop (corn and soybean) with no tree line (ORG Grain NT);
Conventional grain crop (soybean) with tree line (CNV Grain T);
Conventional grain crop (soybean) with no tree line (CNV Grain NT);
Organic vegetable field (mostly cucumbers) with insectary strips (ORG Veg Insect NT);
Organic mixed vegetable field (ORG Veg Mix NT);
Conventional mixed vegetable field (CNV Veg NT).
The recording of the bat calls began at sunset May through September 2016. The recording lasted approximately two hours with a change in location to another agricultural system after the first hour. For example, the first hour recorded calls at the organic orchard with tree line then the recording device was moved to the organic orchard without the tree line for the second hour of recording. This completed one night of monitoring. For the second night of monitoring we reversed the order of the recording at the sites. Recording only occurred on nights without rain and heavy winds.
In areas that included tree lines, the microphones were set up approximately 15 m from the tree line. In the organic grain no tree line monitoring, the microphones were set up approximately 122 m from the closest tree line. In the conventional grain no tree line monitoring, the microphones were set up approximately 183 m from the closest tree line.
To test the hypothesis that agricultural systems affected bat foraging activities, data on passes representing bat activity at every site were subjected to analysis of variance (ANOVA) using the mixed Model procedure of SAS (SAS 9.4, SAS Institute Inc., Cary NC, 2014) at 95% confidence level. Fisher’s protected Least Significant Difference was conducted to separate bat activity between agricultural systems
Bat House Occupancy:
Areas lacking proper vertical structures for bat roosting had bat boxes added in the first spring of the project and monitored into the second year. Two bat boxes per site were installed – a 3-chambered and a 4-chambered box. A set of bat boxes was also installed in an area favorable for bat activity (clearing in trees near farm pond) to determine how bat box type impacts occupancy rates and species, this area also included a new 7-chamber bat box to monitor that size as well. At the end of summer another privately owned 7-chamber bat house was installed near an area that showed high bat activity in our study. And with other funding sources more houses were installed in fall 2016 and 2017. Houses were monitored monthly from May-September each year to look for bat occupancy. This was done by using a flashlight to shine up through the bottom of the bat houses. It was done just before dusk and before bat emergence to increase visibility inside. As of the end of 2017 only one house was occupied and it was one of the 7-chambered houses. This house took only 9 months to become occupied. Bat houses can often take at least 2 years to occupy so no conclusions can be made at this point. This part of the experiment will go on after this project ends because farmers agreed to monitor houses and report on them.
Results with Preliminary data:
Looking at the effects of individual cropping system, the study found no significant cropping system by tree line interaction for bat activity and therefore data was combined for analysis (Table 1). Results from both Pettersson D500x and AR125 were very similar. In each case, there was no significant difference in bat activity monitored during the first hour of the night compared to the second hour. Mean bat activity was greatest in conventional grain system with tree line followed by organic orchard with tree line (Table 1). However, bat passes averaged between the first and second hour were not statistically different between organic apple orchard with tree line and all the other agricultural systems except conventional mixed vegetable field with no tree line and conventional apple orchard with no tree line, both of which recorded the lowest bat passes. A trend was also observed in agricultural systems without tree line whereby organic systems tended to record greater bat activity compared to other systems, even though the differences were not significant.
Broadly looking at the main effects of conventional compared organic agricultural systems, there was a highly significant farming system by tree line interaction for bat activity monitored using both Pettersson D500x and AR125 equipment (Table 2) hence data was analyzed separately by cropping system and tree line. In both organic and conventional systems, tree line had a highly significant effect on bat passes (P < 0.0001). Bat passes were significantly greater in conventional agricultural system with tree line followed by organic system with tree line. There was no statistical difference between the two systems without tree lines even though organic systems tended to register higher bat activity compared to conventional with both monitoring equipment (Table 2).
Bat species identified by the Sonobat software were very similar between the Pettersson D500x and AR125 model acoustic monitoring devices. The greatest proportion of bat species identified were Big Browns (Eptesicu fuscus) at 64% (Figure 3). The proportion of other species identified was quite low in comparison, including 8% Hoary (Lasiurus cinerus), 7% Silver-haired (Lasionyscteris noctivagans), and 2% Eastern Red (Lasiurus borealis). The software could not identify 19% of ultrasonic echolocation calls recorded.
This investigation into bat activity shows significant trends in the impact tree lines have on bat activity even in orchard systems. Areas with tree lines, as previously noted, can provide habitat for bats. Trees may provide vertical structures for connectivity for bats to travel along, provide valuable roosting sites, and diversity in diet. Orchards themselves can attract bat activity but paired with a native tree line, the activity increases. Systems without tree lines seem to show greater bat activity when the system is organic.
The most common species found at all sites was the big brown bat (Eptesicus fuscus). Unlike some species of hibernating bats that have seen declines over 90% due to white-nose syndrome, big brown bats show higher survival of WNS compared to these other species due to its species’ traits and hibernaculum preference (Hayman et al., 2016). Big browns also hibernate in buildings, sometimes the same ones as summer roosts (Whitaker and Gummer, 1992). This ability for big browns to hibernate in dry attics or barns helps them avoid WNS. Significantly greater bat activity in conventional grain cropping system with tree line compared to other systems (Table 1) can be attributed to both the presence of tree line, as already discussed, and more buildings, including old barns and attics, located close to the farm in which this system was located. Absence of significant difference between the other systems can be attributed to absence of tree lines or nearby structures that could provide ideal roosting sites for the bats.
Given the greater role attributed by big brown bats in this study, it is important to better understand their role in pest management and land use. Previous studies have noted the great potential of big brown to provide substantial service to agriculture with over 80% of their diets consisting of agricultural pests such as scarab beetles, spotted cucumber beetles, stink bugs, and leaf hoppers (Whitaker Jr, 1995). With old attics and barns being possible sites of not just summer roosts but also hibernaculum, it is important to educate farmers on the role man-made structures serve in bat conservation. Farmers can be both the beneficiary of these services and also play a large role in bat conservation. Maintaining or installing native tree lines, can provide habitat for all species of bats both common and rare. Educating farmers on the behaviors of bats can also provide them with information in regards to sharing farm structures with the bats in order to support roosting and even hibernation. These structures can support the most common bats like the big brown.
Out of all the bat houses that were installed on poles in 2016, only one showed bat occupancy in 2017. This was one of the 7-chambered houses. Although results will depend on subsequent years of monitoring these houses, it is a positive sign to see a house become occupied in less than a year’s time. Adoption of installing houses will depend on price so although the 7-chambered one seems to be a successful size, its cost is greatly higher than the 3 or 4-chambered houses. Its estimated retail cost is $550, compared to the 4- chambered at $150, and 3-chambered at $80. Personal construction can save on these costs greatly.
Overall, farmers were interested in installing bat houses but lacked the knowledge in roosting behavior and bat house installation. The outreach component became the most important and impactful part of this project.
Things we changed from the original methods plan:
May had a lot of rain so regular monitoring started at the end of May 2016. Driving transects with the acoustic monitoring equipment had poor results and recordings, so we stayed with stationary recording at the study sites. We did monitor riparian buffers but time and weather prevented us from getting enough repetitions to make an equal comparison to the other sites, so we focused on the agricultural systems. Doing that we were able to get a fifth round of monitoring as opposed to the initial four. This gave us more repetitions for running statistics. The data we did have on riparian areas appeared to show high levels of activity when compared to the other areas.
This investigation into bat activity shows significant trends in the impact tree lines have on bat activity even in orchard systems. Areas with tree lines can provide habitat for bats. Trees may provide vertical structures for connectivity for bats to travel along, provide valuable roosting sites, and diversity in diet. Orchards themselves can attract bat activity but paired with a native tree line, the activity increases. Systems without tree lines seem to show greater bat activity when the system is organic. Big brown bats were the most common species found at all study sites. Studies show that the majority of the big brown’s diet consist of major agricultural pests. These bats readily roost in bat houses and man made structures, so providing proper roosting sites can attract greater populations to a farm.
Looking at the results we see tree lines play an important role for bat activity. Tree lines can also help with soil fertility and livestock health so these results can strengthen current recommendations for tree lines and a connection can be made with agroforestry practices. Bats were actively foraging in all of the systems monitored showing the full variety of agricultural landscapes were inclusive of bat foraging.
Education & Outreach Activities and Participation Summary
The project was presented during NE IPM’s second annual online conference. This presentation’s audience is farmers, researchers, extension personnel, and other professionals involved in pest management. This presentation was then written up for Lancaster Farming magazine. Lancaster Farming is the leading Northeast and Mid-Atlantic farm newspaper with more than 60,000 paid subscribers in Pennsylvania and fifteen other states and has been in continuous weekly print since 1955.
Our work was also featured in our media outlets along with two local newspapers (Reading Eagle and Morning Call), US Fish and Wildlife Service’s media outlets, and a nationally published magazine called Rodale’s Organic Life (formerly Organic Gardening). Organic Life magazine has over 300,000 subscribers. Digitally, they have over 1.2 million facebook followers and their website gets 6 million page views per month. While working with US Fish and Wildlife on their media efforts, I assisted NRCS with information on bats and farmers for their outreach efforts in a national campaign for Bat Week 2017.
This project was woven into the institute’s current educational programs and offsite events. It was presented at Rodales Institute’s field day in 2016 and 2017. Attendance in 2016 was 183 people and in 2017 we had our highest year yet with 346 attendees. Presentations included bat houses and installation, results, and acoustic monitoring demonstrations. In both 2016 and 2017 research was also presented to Rodale Institute’s staff, interns, and students in our farmer training program. Some of these presentations happened in the field at dusk. A bat house manual was used as handouts at these presentations. In 2017, bat biology, research methods, and results were presented to 100 STEM teachers through a program that Rodale does with Lancaster and Lebanon School Districts. The teachers visited the Institute to learn more about our work and research to see how they may be able to incorporate it into their classrooms. At off site events the research was presented at Rodale Institute’s booth at both the 2017 Pennsylvania Farm Show in Harrisburg, PA and through direct conversations with farmers at the 2017 Farm Aid in Burgettstown, PA. We aim to hand out our new bat brochures at the 2018 Pennsylvania Farm Show as shown here in the link, Rodale-Trifold-Bat-Brochure
Additionally, Albright College’s ACRES program had students participate in the study and they presented first year results at the 2016 North American Symposium on Bat Research in San Antonio, Texas
I am still consulting with farmers both in person, by phone, or email on bat house installation, maintenance, and monitoring the houses and a peer reviewed publication on this research project is pending.
Farmers gained an increased awareness of bat behavior, roost selection, and the knowledge to understand what roosts they prefer and how to do create that with bat houses. They gained knowledge to better understand the needs of bats that may be currently roosting in farm structures like barns and others were able to trouble shoot why a bat house may never have become occupied.
The press this project has received it has opened doors to other agricultural research institute’s and farmers looking to collaborate. An awardee of a Graduate student grant for Southern SARE modeled her project after this one so we can compare data between different regions and crops. We also worked with a research farm in upstate New York who is beginning to monitor bat activity in agricultural fields and were able to submit a proposal together to expand this work. I have spoken to numerous farmers by phone and email, who have reached out to us after hearing about the work. They call to discuss bat roosts they have and inquire about bat houses. Overall I would say this project is broadening its scope by reaching a general audience just from the unexpected press we have received. There has been extremely positive and favorable interest from the general public about this work.
I personally felt just talking to the public and farmers in a positive and caring way for bats that they began to feel the same way. Most people didn’t have negative feelings about them but rather seemed to lack a basic knowledge. Once basic behavior, conservation needs, and roosting preferences were taught they seemed really motivated to create habitat. I went into this thinking we needed to have outreach to farmers be very detailed on specific research backed bat house selection and I found out the needs to start are much more simple and that they just need some basic info on bats and roosts to want to create habitat. Research and data would be beneficial but really, if anything, time and supplies for installing bat houses would be more limiting than attitude or willingness since most seemed to have a positive attitude.
For the most part the project methods worked out well. If I could change anything it would be to have had more farms/sites involved but that would have required additional funds and another team with equipment. All the repetitions of monitoring nights this project had were great for statistics but it would be nice to have a bigger sample of farms to monitor at. Monitoring happened from end of May to mid September but most of the monitoring happened in June, July, and August and those months appeared to have the most consistent weather, temperature wise, to have higher levels of bat activity so if I was to repeat this study I would focus on monitoring during those three months.
This project was to investigate bat activity across different landscapes in agricultural areas and commodity. The results did show that bat activity increased with natural landscaping such as tree lines regardless of commodity being grown. This trend was observed in both conventional and organic land management. It would be beneficial to repeat this monitoring at other sites just to add more samples (Farms) to the data. However, these results will be disseminated to farmers as a practice to attract bats.
These results would also benefit wildlife managers who are struggling to conserve declining bat populations and habitat loss. Farmers can be a beneficial partner in wildlife conservation and in most cases may share the same interest.