Bat Workshops & Seminar - Survey Recommendations

I. Acoustic Surveys

When deploying ultrasonic detectors to survey bats, workshop participants agreed that there are some fundamental details which must be included when reporting results:

1. EQUIPMENT:

Bat detector manufacturer and model

Sample rate (maximum frequency)

Microphone type (uni- or omni-directional)

Calibration data (i.e., demonstrate quantitatively that equipment, esp. the microphone, is operating within the tolerances of manufacturer's specifications)

Confirmation data on microphone distance-detection range for at least one species of Mormoopidae and one species of Molossidae

Whether recording was Broadband (Full Spectrum) or Narrowband (Heterodyne). If Heterodyne was deployed, the report must explain why Heterodyne was chosen instead of Broadband and specify tuned frequency range(s)

Microphone position: (a) latitude & longitude (incl. track if mobile); (b) vertical positioning (height above ground, attached directly to tree, attached to an artificial pole (specify material), etc.)

Temporal recording parameters (start time, stop time, duration of recordings, duration of pauses in recording)

Whether triggers were used for recording. If yes, provide parameters (e.g., minimum decibel or frequency, post-trigger duration, etc.)

2. AMBIENT CONDITIONS:

Phase of lunar cycle

Time of sunrise / sunset & moonrise / moonset

Air temperature and relative humidity (minimum and maximum for the recording session) [NOTE: air temperature and moisture influence soundwave propagation and attenuation]

Wind conditions (e.g,. Beaufort scale, anemometer) throughout the recording session [NOTE: wind affects wave propagation and will create ultrasonic "noise" at a microphone, esp. if foam windguard is not in-place]

3. ANALYSIS:

Specify the software used to view acoustic recordings

Note whether filters were used to process the files. If "noise" filters were used, copies of all recordings must be archived for independent verification. If verification reveals that "False Negatives" (i.e., bat calls incorrectly classified as "noise", with consequence that those files were not reviewed) exceeds 5% of the recordings (ref Walters et al.2012), the analyses of the recordings will be invalidated and the reported survey results will be rejected

Identify species

When calls cannot be identified to species, explanation should be provided as to which possible species, genus, or taxonomic family, the call(s) may be assigned.

When acoustic surveys are conducted to identify feeding areas, watering holes, or travel flightlines, a Nightly Activity Index of the number of passes per hour per species will need to be prepared.

II. Describing Habitat "Batscapes"

When habitats are described in terms of their plant communities and by their structure in both the horizontal and vertical planes, it becomes possible to predict which bat species will be able to utilize the habitat. This is grounded in the fact that different habitats not only provide variable food resources, but they also influence how a bat travels through the landscape: a bat's echolocating abilities are intrinsically linked to the ecological conditions and each species has a tolerance limit to function in: (a) highly cluttered space (e.g, dense forest); (b) background-cluttered space (e.g., edge habitat); or (c) uncluttered space (open airspace).

In a hypothetical vegetation plot, quantifiable characteristics of a "Batscape" include:

All trees greater than 9.5 centimeters (recorded 10 cm) can be measured at diameter breast height (DBH) and crown height determined either with direct measurement (e.g., telescoping measuring pole, laser range finder) or indirect calculation (e.g., "P scale" height as a percentage of the horizontal distance)

Overstory (crown) density (e.g. using a spherical densiometer)

Understory density of saplings (less than 9.5 cm DBH) (e.g., using a density board)

Tree species identification for diversity and relative abundance indices

Special attention to fig trees (Ficus spp.): figs are extremely important Keystone Species in tropical forests - by fruiting year-round, they contribute more to the survival of frugivorous animals than one would predict by a relative abundance index

Floral characteristics (with focus on identifying flowers for which bats are the predicted legitimate pollinator because of corolla shape and colour)

Fruit characteristics (e.g., small, fleshy fruits that can be carried by bats vs. legume pods which bats can't manipulate, etc.)

Fleming, Geiselman, and Kress' (2009) Appendix 2 New World bat-pollinated species listed by plant family is an invaluable starting-point for predicting which plant species will be pollinated by bats in Jamaica.

Given that bats can easily commute > 10 km from a roosting cave to terrestrial feeding areas (and recognizing that the intervening corridor must meet their acoustic travel requirements), all landuses under Forestry Department's "Forest" Classification (e.g., Closed Broadleaf, Short Open Dry, Mangrove etc., but with the exception of Caribbean Pine and Eucalyptus plantations) should be presumed to be good "Batscapes" for forest-dependent species.

The default for native forest habitats should be: assume pollinating-, seed-dispersing, and insect-eating forest-dependent bats are present unless an exhaustive survey shows otherwise.

III. Survey Guidelines

Identical to bird and other faunal surveys where the objectives of the survey define what will be appropriate survey methodologies and sampling protocols, bat surveys have to be designed with the recognition that there is no single technique that can detect all species of bats equally. Their numerous morphological, physiological, and behavioural adaptations of sensory and motor systems permit bats to have access to a wide range of habitats and resources at night. These adaptations completely influence how we can detect bats and how they can detect us and our equipment.

CONCLUSIONS & RECOMMEDATIONS from the field workshops and seminar
(with supplement from peer-reviewed literature):

Bat surveys required for all proposed power generation developments involving wind farms: reports must contain information on species composition, enumerated activity patterns (i.e. Nightly Activity Index) within and around the proposed turbines, identification of roosting caves and flight corridors, and a table that shows the degree to which each species will be affected by the project's construction and operation. Detection equipment must be positioned correctly to survey the "area of disturbance / risk zone" (i.e rotor-swept area) of turbines.

Bat surveys required for all proposed cave ecotourism activities. [NOTE: Ministry of Tourism's Cockpit Country Ecotourism Guidelines: Caves, Sinkholes and Shafts recognize the ecological sensitivity of bat roosting caves and the health risks posed to humans visiting bat-occupied caves. Caves which contain the fungal spores that cause Histoplasmosis are deemed to be "Off-Limit (Restricted Access) Caves.]

For bat-occupied caves which currently are being used for ecotourism activities, annual monitoring should include a species inventory, recording of persistence or abandonment of any chamber-sections inside the cave, and percentage occupancy of "bell holes" within occupied chambers.

Environmental Impact Assessments (EIAs) can be improved by quantifying habitats to generate a predictive "BatScape" model: if "cluttered forest" and "forest edge" species are predicted, then bat surveys will be warranted if forest-clearing is proposed. If surveys are not conducted, the default should be "assume the forest is important habitat for bats and mitigate to minimize forest conversion and loss of connectivity".

When a bat survey is required by NEPA, the Terms of Reference (ToR) must be explicit as to what is required in the report. Typically, this should include (but not be restricted to): (a) list of species detected; (b) each species' diet niche, "batscape" structural preferences (e.g, cluttered forest, edge, open), roosting requirements, and conservation status; (c) Nightly Activity Index of the number of passes per hour per species, with denotation of deduced behaviour (e.g, fly-through, co-ordinated travel corridor, hunting, drinking water, etc.); (d) mapped positions of all survey points.

Bat surveys must meet the same minimum guidelines for spatial and temporal assessments as currently required for bird and insect surveys.

If identification of feeding areas, drinking water resources, and commuting flyways is required, surveys must be replicated to capture seasonal variation (e.g., wet vs. dry season; breeding vs. non-breeding season [with timing of seasons highly variable amongst nectarivores, frugivores, and insectivores]).

When forest-dependent and cluttered-edge / forest species are detected, roosting caves within a minimum 20-km radius of the surveyed area must be mapped so that mitigation can be directed towards preserving forested corridors between roosting and nursery caves and feeding areas [NOTE: this will require strategic landscape planning by NEPA and Parish Councils at a scale larger than a single EIA can undertake].

With the proper deployment of equipment, the most common bat species utilizing an area are usually detected within several nights of continuous sampling (Meyer et al. 2011). Metrics can be developed to describe the common ecological network structure so that environmental impacts (e.g., species turnover; changes in activity patterns) of a proposed landuse conversion can be predicted and evaluated with short- and longer-term monitoring (Meyer et al. 2015).

If a Species Richness Index is required, a short sampling period of several nights will almost certainly miss rare species, with a consequence that inferences about species richness in an area will be underestimated. Meyer et al. (2011) recommended conducting four replicate surveys (with appropriate techniques) per sampling unit within a given year to reduce bias.

In choosing appropriate surveys techniques to fulfill ToR, strengths and weakness of techniques must be understood both by the regulatory Agency and professionals conducting the surveys:

(a) Ultrasonic bat detectors are most effective for detecting bats which use lower frequency and narrow bandwidth calls (e.g., aerial insectivores, such as the family Molossidae) and bats that emit Constant Frequency (e.g., Pteronotus parnellii) or Quasi-Constant Frequency/Frequency Modulated calls with moderate bandwiths (e.g., the family Mormoopidae).

(b) Ultrasonic bat detectors are poor at detecting species which emit very high frequencies or Frequency Modulated calls with wide bandwidths. This includes gleaning insectivores and nectarivores in the family Phyllostomidae ("whispering" bats) and insectivores in the family Natalidae.

(c) Exceptions to the "whispering" Phyllostomidae rule are the Jamaican Fruit Bat (Artibeus jamaicensis) and the endemic, tree-roosting Jamaican Fig-eating Bat (Ariteus flavescens ). Artibeus jamaicensis can emit an intense call of ~ 100 decibels (measured 10 cm from its mouth) and radio-transmittered Ariteus flavescens could be detected acoustically to about 3-5 meters. Coupled with Mormoopidae, establishing baseline Nightly Activity Indices and monitoring for changes in activity patterns is feasible and practical with acoustic surveys for these species in forest and forest-edge habitats.

(d) Distance-detection range with bat detectors will always be limited by the acoustic properties of the calls emitted by the bats: if a proposed development structure is going to occupy the airspace 50 m above the ground, then the bat detector must be elevated to ensure that airspace is correctly evaluated.

(e) Capture of Bats: While detection of species presumed to be rare or uncommon may be increased by employing multiple methods, such as ground-based and canopy-based mist nets and harp traps (Pio et al. 2011 Meyer et al. 2011), these techniques also have biases. For example, they are limited to surveying only their area-of-interception and mist nets fluttering in even a slight breeze (Beaufort #2; blowing < 5 km / hr) may be detected and avoided, esp. by insectivorous bats.

ALERT: Mist nets can (will) be LETHAL to wildlife if they are deployed by untrained persons.

Because diurnal birds as well as bats can be captured at dusk and dawn and nocturnally-active wetland birds (e.g., shorebirds, night-herons, etc.), owls, nightjars, and potoos may be captured throughout the night, seminar participants who have been trained to handle both birds and bats advise that only those persons who have been permitted by international banding / ringing schemes should be allowed to deploy mist nets unsupervised in Jamaica until national skills-certification is established. This is both for the safety of the wildlife as well as for the safety of the person handling the animals.

There are many opportunities for professional training at numerous bird banding stations in North America and Europe. The North American Banding Council's Instructor's Guide has detailed descriptions of the minimum levels to which someone must be trained to safely use mist nets.

Persons who have been trained to handle birds but not bats should start their training by referring to the Bat Workers' Manual, 3rd ed. published by Joint Nature Conservation Committee (UK). Although general descriptions are given for the safe deployment and extraction of bats from mist nets, bird banders need to be trained so they do not break the bat's forearm while working the net free from the elbow and carpal joints. Of additional usefulness, the manual describes the licensing system for those needing to work with bats in the UK. For example, a Class Licence Level 3 is required to deploy mist nets and acoustic lures while a Class Licence Level 4 is required to deploy harp traps.

Persons also should be aware that all birds in Jamaica are protected unless they appear on the Second Schedule of the Wild Life Protection Act. In the absence of a permit issued by NEPA, their capture in mist nets, even if incidental ("by-catch") is an offense against the Act and can result in a fine of up-to JD 100,000 or one year in jail.

Bats must be added to the Wild Life Protection Act Third Schedule to ensure their full protection.

While artificial bat houses may be erected to try and eliminate human-wildlife conflicts when bats are roosting in buildings, the majority of bat species in Jamaica are obligate cave-roosters and will not use artificial structures. The deployment of bat houses will not mitigate the destruction of a natural cave nor will it mitigate the loss of foraging habitats and travel corridors.

Windsor Research Centre would like to extend a special thank you to all field workshop and seminar participants for their contributions to what we hope will lead to improved conservation of bats, the ecosystem services they provide, and their terrestrial and subterranean habitats.
Please if you have any questions or additional comments.

Useful References

- - 2000. Biophysical Inventory Manual. Trees for Tomorrow Project, Phase II. Joint project between Forestry Department (Ministry of Agriculture, GoJ) and Tecsult International (Canada).

Clare, E.L., H.R. Goerlitz, V.A. Drapeau, M.W., M.W. Holderied, A.M. Adams, J. Nagel, E.R. Dumont, P.D.N Herbert, and M.B. Fenton. 2014. Trophic niche flexibility in Glossophaga soricina: how a nectar seeker sneaks an insect snack. Functional Ecology v28. http://dx.doi.org/10.1111/1365-2435.12192.

Emrich, M.A., E.L. Clare, W.O.C. Symondson, S.E. Koenig, and M.B. Fenton. 2013. Resource partitioning by insectivorous bats in Jamaica. Molecular Ecology 23: 3648-3656.

Fleming, T.H., C. Geiselman, and W.J. Kress. 2009. The evolution of bat pollination: a phylogenetic perspective. Annals of Botany 104: 1017-1043.

Hayward, C.E. 2013. DNA barcoding expands dietary identification and reveals dietary similarity in Jamaican frugivorous bats. Electronic Thesis and Dissertation Repository. Paper 1697. http://ir.lib.uwo.ca/etd/1697

Kay, E. 2001. Observations on the pollination of Passiflora penduliflora. Biotropica 33:709-713.

Lobova, T.A., C.K. Geiselman, and S.A. Mori. 2009. Seed dispersal by bats in the Neotropics. The New York Botanical Garden, NY, USA

MacSwiney, M.C., F.M. Clarke, and P.A. Racey. 2008. What you see is not what you get: the role of ultrasonic detectors in increasing inventory completeness in Neotropical bat assemblages. Journal of Applied Ecology 45: 1364–1371.

Meyer, C.F.J., L.M.S. Aguiar, L.F. Aguirre, J. Baumgarten, F.M. Clarke, et al. 2011. Accounting for detectability improves estimates of species richness in tropical bat surveys. Journal of Applied Ecology 48: 777-787.

Meyer, C.F.J., L.M.S. Aguiar, L.F. Aguirre, J. Baumgarten, F.M. Clarke, et al. 2015. Species undersampling in tropical bat surveys: effects on emerging biodiversity patterns. Journal of Animal Ecology, 24: 113-123.

Petrov B. 2008. Bats – methodology for environmental impact assessment and appropriate assessment. A manual for developers, environmental experts and planning authorities. National Museum of Natural History-BAS, 88 p.

Pio, D.V., F.M. Clarke, I. Mackie, and P.A. Racey. 2010. Echolocation calls of the bats of Trinidad, West Indies: is guild membership reflected in echolocation signal design? Acta Chiropterologica 12: 217-229.

Rodrigues, L., L. Bach, M.-J. Dubourg-Savage, J. Goodwin & C. Harbusch. 2008. Guidelines for consideration of bats in wind farm projects. EUROBATS Publication Series No. 3 (English version). UNEP/EUROBATS Secretariat, Bonn, Germany, 51 pp.

Schnitzler, H.-U. and E.K.V. Kalko. 2001. Echolocation by insect-eating bats. BioScience 51: 557-569.

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Acknowledgements:
Funding for the seminar was provided by: