Abstract	Capture Data
Species of bats on MNI	Before/After Photographs
Research Topics	Wonderful People
Sub-lethal Pathology in Bats	More Bat Research in the Region

Montserrat - Northern Lesser Antilles

The British Crown Colony of Montserrat is a small 100 sq. km. island located in the northern Lesser Antilles. It was named by Columbus in 1493 and colonized by the British plantation system (Sugar cane, Cotton, Limes) in 1632. Before the Soufriere Hills volcano erupted in 1995, the island of Montserrat was a tropical paradise (known as the Emerald Isle) untouched by tourists and commercial developments. Montserratians take a fierce pride in the heritage and natural beauty of their small island. Montserrat lies nearly 30 miles southwest of Antigua. The north-east corner is quite arid, while the rest of the island had been covered in a lush forest mixed with pasture and farm land. At 16 degrees north of the equator, Montserrat is hot and tropical. Temperatures range from 76-88 F and the rainfall averages around 60" a year.

[PDF of Montserrat article: Carib. J. Sci. - 1996]
[PDF of Montserrat article: Natural History. 2003]
[PDF of Bat Population Genetics article: Molecular Ecology - 2004]
[PDF of Biodiversity Assessment of the Centre Hills: 2008]
[PDF of Book Advertisement: Bat population fluctuation: 2009]
[Link to MNI National Trust: Guide to the Centre Hills: 2009]

K. Questel (photo)

OVERVIEW OF RESERACH EFFORTS ON MNI

The Lesser Antilles are unique in that they exhibit high levels of endemism and have a taxonomic composition more akin to isolated oceanic islands. The effects of natural disturbances such as hurricanes/volcanoes on these exposed biotas are so intense that island habitats may take decades to recover. Montserrat is located in the middle of the ‘hurricane belt’ and has been battered by 28 hurricanes in the last 359 years, with Hugo (1989) being the most destructive in recent history. Seismic activity on Montserrat has caused a great deal of damage in the past (1898, 1934). Historically, seismic activity on Montserrat is not uncommon. Earthquakes have caused a great deal of damage in the past with major events occurring in 1898 and 1934. Since 1995, pyroclastic flows from the active Soufriere Hills volcano have reduced much of the southern half of the island to an ecological wasteland, destroying roost sites and 50% of the islands foraging habitat. The series of natural disasters experienced by Montserrat provide an extraordinary opportunity to observe how the synergistic effects of two types of natural disasters and the associated loss of habitats affect island biodiversity.

(above) Satellite imagery of Hurricane Hugo - September 1989
(below) Aerial photograph of the pyroclastic ash 'aprons' on Montserrat

Of great interest is the reappearance of two very rare species of bat that were captured in 2005 during the Centre Hills Biodiversity Project. Chiroderma improvisum had not been netted on Montserrat during the period 1993-2004 and we have only the single record of Sturnira thomasi from 1994. In the intervening years 1993-2004, we had entertained the idea that perhaps both Chiroderma and Sturnira were transient species - Chiroderma having been blown off of Montserrat and Sturnira being introduced to Montserrat from Guadeloupe all thanks to Hurricane Hugo. In retrospect, these musings were naïve and with the rediscovery of both taxa in 2005, it would appear that these species had simply become so rare as to become 'invisible' to our mistnetting efforts. Indeed, additional data collected in 2005 regarding mistnet capture bias indicates that less than 5% of bats flying along traditional flyways (trail, road, riverbed) actually become snared in a mistnet (Larsen et al., 2005). These data closely mirror data collected by Lang et al., (2004) in Panama. If this is so, then mistnetting surveys are clearly underestimating species diversity and bat activity.

Cast of Characters

The first voucher (Brachyphylla cavernarum) was collected by Mr. Sturge in 1893 from an unknown location on the island. Since then, 17 further surveys (1978-2009) have produced a database including well over 3200 captures of ten species (Artibeus jamaicensis, Ardops nichollsi, Brachyphylla cavernarum, Chiroderma improvisum, Sturnira thomasi, Monophyllus plethodon, Natalus stramineus, Tadarida brasiliensis, Molossus molossus, Noctilio leporinus).

 

Online Field Guide to the Bats Shown Below

(Photo A. Hartpence)

Bat Research on Montserrat

Apart from the minor inconvenience of being blown apart by hurricanes and being incinerated by pyroclastic flows (1995-99), the bats of Montserrat have recently suffered through two draught years (2000-01). Given this run of bad-luck, our database is rather unique in that it documents how this relatively isolated fruit bat population has responded to three diverse natural disasters over a 25 year period (1978-2002). Predictably, fruit bat populations have decreased after each successive disaster due to direct or indirect affects on foraging and roosting habitats. During the volcanic activity (1995-2000), the fruit bats were hard pressed to find adequate forage and housing, and they exhibited several non-lethal stress-related pathologies (see below) associated with the incidental ingestion of volcanic ash. These problems became increasingly common as the volcanic crisis continued. The 2002 census followed on the heels of a cessation in significant volcanic activity and two years of draught. 2002 was the first “normal” (i.e., wet) Spring since 1995. Indeed, several varieties of fig trees that had not been observed to produce a significant fruit set since 1995, were heavy with fruit during July 2002. Fruit bat capture rates during 2002, at stations that have been repeatedly sampled since 1993, indicated that overall capture rates were 3.4X greater than those during the peak of volcanic activity (1997-98) and 1.5X greater than the previous census in 2001. This rather dramatic fluctuation in the fruit bat population is driven almost entirely by an increase in both the absolute and relative numbers of Artibeus and Monophyllus captured (e.g., 0.09 vs. 0.56 Monophyllus captures per net per night; 0.31 vs. 2.39 Artibeus per net per night). Ardops and Brachyphylla are monoestrous producing a single pup per year and very little is known of the reproductive cycle and reproductive potential in Monophyllus. However, Artibeus is polyestrous and usually produces 2 pregnancies per year, but is capable of producing 3 if there is no delay. Given this reproductive potential, populations of Artibeus are clearly capable of, and perhaps predisposed to, rapid recovery following disturbances such as those noted on Montserrat. Indeed, 66% of all captures in 2007 were of Artibeus.

Online Field Guide to the Bats Shown Above

RESEARCH OBJECTIVES IN THE REGION

Our primary goal is to document the declines in the bat population and their subsequent recovery after two major natural disasters, namely Hurricane Hugo and the Soufriere Hills Volcano. This will entail the continuation of census efforts on the island of Montserrat (MNI). In parallel, we also intend to pursue census efforts on the adjacent islands of Antigua, St. Kitts, and Nevis. Antigua (ANU) is in an excellent position to serve as a natural control for numerous questions concerning biogeography, local extinction rates, and the impact of natural disasters on bat populations for numerous reasons, a) proximity to Montserrat (MNI), b) equidistance and direction of ANU and MNI downwind from Guadeloupe (storm dispersal of animals), and c) ANU has not been damaged by major storms (or volcano's).

Species-area curve
# species of bat plotted against
each island's surface area.

ISLAND BIOGEOGRAPHY

Dispersal of bats throughout the Lesser Antilles is influenced by regional storm patterns, species vagility, and distances among islands. Yet, despite our wealth of survey data from the region, actual movements of bats throughout the Lesser Antilles are poorly known, but have been thought to be limited because inter-island distances present formidable barriers to dispersal and gene flow among islands, and perhaps these barriers are insurmountable given the navigational abilities of bats. Nevertheless, bat populations throughout the northern Lesser Antilles might arguably be considered a metapopulation (population of populations) and the local extirpation of a species from a severely damaged island may not matter as bats may readily re-colonize the island from adjacent islands. However, one looming question remains unanswered: Can the contemporary distribution of bats in the Lesser Antilles be accounted for by spontaneous movements among islands or is the movement and distribution of bats driven predominately by the impact of tropical storms and hurricanes?

Despite the recent attention to Rapid Biodiversity Assessments and their potential benefit as being a pragmatic initial effort (UNEP 2006, EPA 2006), perhaps we need to re-evaluate our survey protocols and understand that there should be nothing rapid about an accurate biodiversity assessment for bats. Short-duration and/or single season surveys would have seriously underestimated bat biodiversity on Montserrat during the years 1994-2004, reporting only 5 to 8 species as being present, not the ten that have been recorded. For Montserrat, our species accumulation curve peaked in the vicinity of 1000 captures and 100 net-night -- values that are similar for many islands in the immediate region. The capture of very rare species requires a significantly greater investment of time and effort. For example, given our cumulative efforts on Montserrat that include 780 net-nights and 2602 total captures, we have capture records for only three Chiroderma improvisum, and two Sturnira thomasi. We conclude that without long-duration/multi-year survey efforts, biodiversity estimates can only be approximations at best and quite probably grossly underestimate the true faunal diversity of an island, thus providing a poor foundation for any subsequent conservation guidelines.

(Photo R. Adams)

DENTAL ATTRITION

We are currently seeking funding to continue our work on Montserrat, which will emphasize investigations into species-specific patterns in tooth wear that can be attributed to the abrasive affects of ash, and the structure of preferred food items. Since the onset of volcanic activity in 1995, we have examined the dentitions of several hundred bats and have recorded damage ranging from moderate to severe tooth wear presumably from chewing ash-laden fruits and from incidental ingestion of ash during grooming. The dentitions of museum voucher specimens collected before the eruptions show less wear than those of recently collected specimens (see graph above). Before 1998 (peak volcanic activity), only 3 of 641 (< 1%) fruit bat captures recorded any incidence of tooth wear - and these were old, heavily-scarred bats. Since 1998, the incidence of abnormal dental attrition has continued to increase in Artibeus and Ardops at a steady rate. This is probably related to the cumulative effects of the ash in all age groups - only juveniles and young of the year demonstrated unaffected teeth. Tooth wear in Brachyphylla has apparently decreased (see figure), albeit, there is a sampling bias that needs to be rectified for this species. Under magnification, the occlusal surfaces of the teeth (Brachyphylla) exhibit neither gouges nor pits, but rather, they appear highly burnished. These wear patterns are not the result of occlusal thagosis, but are due to the wear and subsequent ablation of the enamel crown under the abrasive insult of volcanic ash. The teeth of larger bats with robust dentitions are affected to a greater extent than the teeth of the more gracile, small fruit specialists. Despite the observation that small fruits (Clammy cherry, Piper) carry more ash, and present more ash per mouthful, than larger fruits (Almond, Mango), small fruit specialists do not exhibit excessive tooth wear. On the other hand, the two large frugivores B. cavernarum and A. jamaicensis have demonstrated tooth wear/loss since 1997 (see above: SEM photographs of tooth wear patterns in Brachyphylla). Certainly, the feeding habits of these animals includes foraging throughout the crowns of fruit trees where the fur accumulates great amounts of ash. This ash must be groomed off and is subsequently ingested by the bats. We are anxious to investigate the direct effects of ash on the tissues of the respiratory and digestive systems.

(Photo R. Adams)

IDIOPATHIC ALOPECIA

Before 1997, hair-loss (alopecia) had been observed once in a very old lactating female Artibeus. During the peak volcanic activity, 1997-1999, hair-loss was quite common in fruit-bats (25%) captured during that period. During the 1998 census of a large maternity colony of Brachyphylla, 25% of the ~15,000 adult animals were fully-furred, 25% were nearly bald on the dorsum, shoulders, and head, and 50% suffered less obvious, but substantial hair-loss. This excessive hair-loss could be attributed to a wide range of causative-factors: physiological stress due to habitat/roost destruction; roost-parasitism; mineral deficiencies due to inadequate diet or improper digestion of food [Zinc-deficiency alopecia?]. The metabolic demands of lactation are frequently associated with transitory hair-loss. However, less than 50% of the balding bats during 1997-99) were lactating or pregnant. After the brief cessation in volcanic activity in 2000, the incidence of hair-loss decreased substantially in both Artibeus and Brachyphylla, but hair-loss was obvious once again during the last 3 surveys (2000-2002) albeit limited to pregnant and lactating animals. Lactation is obviously correlated with hair-loss, but during peak volcanic activity other forcing factors were at work in these fruitbats.

Roosting Behavior, Natural Disasters, & Competition - A Case Study:
Before 1995, the colony of B. cavernarum alternated between a large roost site in Mosquito Ghaut and the sea-cave at Rendezvous Bluff. For several weeks at a time, each served as a regional shelter from which the colony would mob fruiting trees in the vicinity. The Mosquito Ghaut roost was destroyed by pyroclastics in 1995, leaving Rendezvous Bluff as the only known roost site for this large colony. Despite the loss of an important roost, the population of B. cavernarum was 3-4 larger than that recorded in 1994. However, many individuals in this colony are plagued by excessive loss of fur (97-98). Streblid flies are very common on these bats, but mange mites were not found on any of the specimens checked. This excessive hair-loss is perplexing, but is most likely related to a combination of stresses imposed on this large maternity colony as a result of the deteriorating environmental conditions on the island (reduction in foraging area, reduced fruit resources, roost-crowding, and roost-parasitism). In 1998, we visited the Rendezvous Bluff roost (accessible only by sea) where approximately 25% of the ~15,000 adult animals were fully furred, had pups, and appeared healthy. However, 25% were nearly bald (mostly on the dorsum, shoulders, and head), and 50% suffered less obvious, but substantial hair loss. In the 2000, 2001, 2002 surveys, we noted that this population had fragmented into a maternity colony occupying the southernmost cave, while males were excluded to the smaller, vertical cave immediately to the north.

Predictably, bat species that are hardest hit by hurricanes and volcanoes are those that are tree-roosting specialists. Cave-roosting species (B. cavernarum) receive protection from the direct affects of such disasters, yet must still contend with destruction of their food resources. Species with catholic roosting preferences would be less affected than tree-roosting specialists. The loss of the standing fruit crop and the loss of entire fruit trees would predictably disrupt all frugivores. However, generalist frugivores and omnivores would be less affected and could likely survive through the lean times during island recovery by exploiting hardy fruits that might remain on trees, or even by shifting to insect prey (i.e., B. cavernarum). In terms of pyroclastic flows and ash fall, generalists would predictably survive in higher numbers than specialists for many of the same reasons listed above. The remaining populations of bats are limited to what habitat remains at the northern, xeric end of Montserrat. Predictably, competition for food is likely more intense, a circumstance for which B. cavernarum is well adapted; this aggressive species has been observed displacing A. jamaicensis from feeding sites. This suggests that the success of the B. cavernarum population on post-volcano Montserrat is based upon this species' ability to aggressively defend remaining and potentially limited food resources. Regardless, populations of Artibeus have mushroomed through the last 3-4 years, primarily because Artibeus can simply out-reproduce the other species of bats on the island. Artibeus is clearly the dominant species on island with 66% of all captures in 2007.

(Photo A. Hartpence)

Continuing bat work in the Northern Lesser Antilles...

MNI 1994 Pedersen (Hadley, Lahti-Parsell)
ANU 1994: Morton and Day, 1994
MNI 1995: Morton and Day, 1995
MNI 1996: Pedersen et al., 1996 (Caribbean J. Science, 32:206-213)
MNI 1997: Pedersen
MNI 1998: Pedersen and Adams (Atkinson, Daane, Daly, Grey, Murrain)
ANU 1998: Pedersen and Adams (Cooper)
SKB 1999: Morton and Courts, 1999
NEV 1999: Morton and Courts, 1999
MNI 2000: Pedersen (Swier, Appino, Ratcliffe, Murrain)
ANU 2000: Pedersen (Swier, Appino)
NEV 2001: Pedersen (Acta Chiropterologica - accepted for publication)
SKB 2001: Pedersen, Genoways, Kwiecinski
MNI 2001: Pedersen, Kwiecinski, Hadley
SAB 2002: Pedersen, Huebschman (Hartpence, P. Larsen, South)
EUX 2002: Pedersen, Huebschman (Hartpence, P. Larsen, South)
SXM 2002: Pedersen, Kwiecinski, Huebschman (Hartpence, P. Larsen, South)
MNI 2002: Pedersen, Kwiecinski, (Hartpence, P. Larsen, South)
BBQ 2003 Pedersen, Genoways, P. Larsen
ANU 2003 Pedersen, Genoways, P. Larsen
SXM 2003 Pedersen, Genoways, P. Larsen
SAB 2003 Pedersen, Genoways, P. Larsen
EUX 2003 Pedersen, Genoways, P. Larsen
SXM 2004 Pedersen, Genoways, P. Larsen
SBA 2004 Pedersen, Genoways, P. Larsen
EUX 2004 Pedersen, Genoways, Kwiecinski, P. Larsen
MNI 2004 Pedersen, Genoways, Kwiecinski, P. Larsen
MNI 2005 Pedersen, Kwiecinski, Adams (K. Boegler, R. Larsen)
SVD 2005 Kwiecinski, Pedersen, Genoways, P. Larsen, B. Bales
MNI 2006 Pedersen, R. Larsen (K Cudmore, J Kolba)
SVD 2006 Kwiecinski, Pedersen, Genoways, Hoffman, Larsen (n=3), Cudmore, Homnick, Kolba
MNI 2007 Pedersen, Clarke
SLU 2007 Kwiecinski, Pedersen, Genoways, R. Larsen, Clarke
BGI 2007 Kwiecinski, Pedersen, Genoways, R. Larsen, Clarke
2008 BGI, SLU, MNI
2009 SLU, EUX, MNI

Thanks to some great people!

I wish to express my gratitude and great admiration for the efforts made by the Hollender Estate towards the protection of Montserrat's wildlife, forests, and heritage through what can only be described as super-human efforts. We also express our thanks to Douglas Darby for his interest in biological research on MNI and to kind people who permitted access to their Estate properties: Beadles, Emmanuels, Whites.

A heart-felt Thank-you is offered
to all those who have contributed
to this project over the last 13 years!

Scott Pedersen

COLLEAGUES: Rick Adams; Dave Fawcett, Hugh Genoways, Karen Hadley,
Gary Kwiecinski, Will Masefield, Matt Morton, John Ratcliffe, Phil Atkinson (not pictured)

Great thanks to several Forestry officers and biologists on Montserrat for their assistance in the field (alphabetical):
James 'Scriber' Daly, Calvin 'Blacka' Fenton, John 'Gambie' Martin, Phillemon 'Pie" Murrain, Wolf Krebs
(not pictured: Gerard Grey, Steven McNamara, Bryan Cunningham)

Schooner's Bar
Old Norwood, Montserrat

Pictured:
- Philemon 'Pie' Murrain
- Ibraham 'Schooner' Baker

 

Finest watering-hole on the planet

We offer thanks to the following for continued interest in our research and partial funding in 2005