A collection of common barn-owl (Tyto alba Scopoli) pellets from caves on the Portland Ridge of Jamaica reveals that whereas introduced rodents constitute approximately 90% of the total prey, bats and birds are also frequent prey items. Of the bats, frugivorous species predominate with Ariteus flavescens Gray and Artibeus jamaicensis Leach accounting for the largest portion of the bat prey. Insectivorous bats are markedly under-represented with respect to the known diversity of insectivorous species in the habitat

Garrett, Kimball L.

McFarlane, Donald A.

English

Keck Graduate Institute

Claremont Colleges
Scholarship @ Claremont
WM Keck Science Faculty Papers W.M. Keck Science Department
1-1-1989
The Prey of Common Barn Owls (Tyto alba) in
Dry Limestone Scrub Forest of Southern Jamaica
Donald A. McFarlane
Claremont McKenna College; Pitzer College; Scripps College
Kimball L. Garrett
This Article is brought to you for free and open access by the W.M. Keck Science Department at Scholarship @ Claremont. It has been accepted for
inclusion in WM Keck Science Faculty Papers by an authorized administrator of Scholarship @ Claremont. For more information, please contact
scholarship@cuc.claremont.edu.
Recommended Citation
MacFarlane, D.A., and K. L. Garret. "The prey of common barn owls (Tyto alba) in dry limestone scrub forest of southern Jamaica."
Caribbean Journal of Science 25 (1989): 21-23.
Caribbean Journal of Science, Vol. 25, No. 1-2, 21-23, 1989
Copyright 1989 College of Arts and Sciences
University of Puerto Rico, Mayaguez
The Prey of Common Barn-Owls (Tyto alba) in Dry Limestone
Scrub Forest of Southern Jamaica
D O N A L D  A .  MC F A R L A N E 1 A N D  K I M B A L L  L. GA R R E T T2
1Section of Mammalogy, Natural History Museum of Los Angeles County,
Los Angeles, California 90007, and
2Section of Birds, Natural History Museum of Los Angeles County,
Los Angeles, California 90007
ABSTRACT . – A collection of common barn-owl (Tyto alba Scopoli) pellets from caves on the Portland
Ridge of Jamaica reveals that whereas introduced rodents constitute approximately 90% of the total prey,
bats and birds are also frequent prey items. Of the bats, frugivorous species predominate with Ariteus
flavescens Gray and Artibeus jamaicensis Leach accounting for the largest portion of the bat prey. Insec-
tivorous bats are markedly under-represented with respect to the known diversity of insectivorous species
in the habitat.
INTRODUCTION
The prey of barn-owls on Caribbean is-
lands is of special interest because of the
contribution that owl-pellet accumulations
have made to the palaeontological record
(Pregill and Olson, 1981), and because owl
pellets provide faunal samples in areas
which may otherwise be poorly known in
this respect. Modern owl-pellet accumu-
lations have been reported from Grand
Cayman (Johnston,  1974) ,  Hispaniola
(Wetmore and Swales, 1931), and the
southern Bahamas (Buden, 1974). These
studies have suggested that the relatively
depauperate small mammal faunas of the
Bahamian and Antillean islands may have
forced a degree of dietary shift upon island
owl populations. Recently, Schwartz and
Bleitch (1985) have provided evidence
which indicates that the proportions of prey
taxa in barn-owl pellets collected in south-
ern California reflect true prey densities,
an observation which reinforces the value
of owl pellet studies.
METHODS
In June of 1985, osteological material was
collected from large owl-pellet deposits on
the talus cones of two deep collapse pits,
Arrow Pit and Entrance 1, Somerville Cave
(Wadge et al., 1979). These caves lie in the
dense coastal arid faciation of the dry lime-
stone scrub forest (Asprey and Robbins,
1952), close to the village of Jackson’s Bay,
Clarendon Parish, Jamaica. Arrow Pit is ap-
proximately 20 metres deep, and Entrance
1 of Somerville Cave measures some 15
metres from lip to talus slope. Both pits
have steeply overhanging walls with many
ledges and alcoves frequented by barn
owls.
The deposits were of two types; discrete,
young pellets on ledges, and very large
accumulations of loose bone apparently
scattered from ledges downward onto talus
slopes. The size of the deposits, which at
Somerville occupied an estimated floor area
of 100 m2, together with the heterogeneous
disposition of prey taxa precluded the col-
lection of a truly random sample in the
time available. In practice all non-rodent
crania encountered in 10 man-hours of
search at the two sites were collected, to-
gether with a large but partial sample of
the rodent material. Thus the relative pro-
portions of the non-rodent taxa are con-
sidered to be a true representation of their
proportions at the sites, but the proportion
of rodent to non-rodent specimens is biased
in favor of non-rodents. Specimen num-
bers are given as minimum number of in-
dividuals (MNI) since crania and mandi-
bles were always disassociated.
22 D. A. McFARLANE AND K. L. GARRETT
TABLE 1. Vertebrate prey taxa from owl-pellet de-
posits at Jackson’s Bay.
Mini- % of
mum # non-
of indi- rodent
Taxon viduals total
Mammalia; Rodentia
Rattus rattus (L.) 900-950
Mus musculus (L.) 20-25
Mammalia; Chiroptera
Artibeus jamaicensis (Leach) 16
Ariteus flavescens (Gray) 22
Erophylla sezekorni (Gundlach) 8
Monophyllus redmani (Leach) 2
Eptesicus lynni (Shamel) 4
Aves
Icterus leucopteryx (Wagler) 3
Vireo altiloquus (Vielliot) 4
Coccyzus sp. (americanus?) 3
Tiaris olivacea (L.) 3
Tyrannus sp. (dominicensis?)
(Lacepede) 4
Loxigilla violacea (L.) 7
Dumetella carolinensis (L.) 1
Myiarchus sp. (Stolidus?)
(Cabanis) 1
Unidentified 2
Reptilia
Anolis garmani (Stejneger) 2
19.5
26.8
9.7
2.4
4.8
3.6
4.8
3.6
3.6
4.8
8.5
1.2
1.2
2.4
2.4
RESULTS
Seventeen taxa of vertebrates were iden-
tified from the Jackson’s Bay collections,
which were dominated by the remains of
the introduced rat Rattus rattus Linnaeus.
Of the non-rodent prey items, 63.4% were
bats, 34. 1% were birds, and 2.4% were liz-
ards. Table 1 lists the species identifica-
tions together with the minimum number
of individuals represented.
D ISCUSSION
The only native rodent currently extant
on Jamaica is Geocapromys brownii Chap-
man, whose adult size (1000-2000 g) makes
it an unlikely prey item for barn-owls. Geo-
capromys brownii is known from the Jack-
son’s Bay caves but not from owl-pellet
material. The black rat, Rattus rattus, is by
far the dominant prey item at both Arrow
Pit and Somerville Cave. An estimated 90%
of the total prey items at these sites were
R. rattus. The house mouse, Mus musculus
Linnaeus, was quite scarce in the deposits
and accounted for no more than 2% of the
total prey items. These figures compare
with 87.5% and 3.9%, respectively, for pel-
lets collected at Morne La Viste, Haiti, by
Wetmore and Swales (1931).
Five species of bats were identified from
the Jackson’s Bay collections. The selection
of bat prey by the owls is apparently un-
related to prey size, since the commonest
prey species (Ariteus flavescens, 12 g, MNI
= 22) is very close to the size of the two
least common prey species (Eptesicus lynni,
12 g, MNI = 4; Monophyllus redmani, 12 g,
MNI = 2) whereas the second commonest
prey species (Artibeus jamaicensis, 35 g, MNI
= 16) is at least three times as large. Another
large species, Erophylla sezekorni, (35 g, MNI
= 8) was also represented. It is interesting
to note that the three commonest prey
species are all frugivores, although E r o -
phylla takes significant quantities of flow-
ers and nectar also. It is possible that the
slow flight of these species and their pre-
dictable occurrence at fruiting trees ren-
ders them more vulnerable to aerial pre-
dation.
Ariteus flavescens is know from only two
recent literature records of the living an-
imal ,  one of  s ix  specimens from the
“Kingston area” (Williams, 1952) and one
of three specimens from Hector’s River,
Portland Parish (Howe, 1974). Additional
specimens from Kingston (D. L. Harrison,
pers. comm.) and “St. Thomas” (British
Museum, Natural History) are also known.
Since these localities are all relatively me-
sic, the fact that Ariteus is apparently a com-
mon species in the dry limestone scrub of
Jackson’s Bay implies that it is probably
widely distributed across the island.
Eptesicus lynni is also known from very
few literature records (Hall, 1981). The re-
covery of at least four individuals from
Jackson’s Bay implies that this species also
may be more widely distributed than has
hitherto been supposed. The insectivorous
bat Macrotus Waterhouse Gray was collected
alive from Jackson’s Bay during this field-
work, but is not represented in the owl-
pellet material. It is unlikely that these are
PREY OF JAMAICAN OWLS 23
the only two of Jamaica’s 13 insectivorous
bats to occur in this habitat.
The numbers of avian prey do not sug-
gest any particular specialization by the
owls, but probably reflect local species
abundances. Lack (1976) regards only Du-
metella carolinensis as scarce in Portland
Ridge habitat. A tendency for avian prey
of barn-owls to consist of communally-
roosting species has been noted (Cramp,
1985); of the avian prey species in this
study, only the grassquits (Tiaris) and per-
haps the bullfinch (Loxigilla) might be con-
sidered communually-roosting species.
The lizard Anolis garmani is clearly un-
der-represented with respect to its’ abun-
dance at Jackson’s Bay, suggesting that owl
predation is not important for this species.
The diversity of bat species represented
in the owl-pellet accumulations provides
a minimum estimate of species richness in
the bat community of Jamaican dry scrub
forest. The predominance of Ariteus flaves-
cens, a bat which is rare in museum col-
lections taken from the island, suggests that
either the status of this species has been
seriously underestimated or that it is dis-
proportionately vulnerable to barn-owl
predation. The marked under-representa-
tion of insectivorous bats in the owl pellets
suggests that it would be unwise to use
these deposits alone to reconstruct a whole
bat fauna.
Acknowledgments. — We are indebted to
Richard E. Gledhill for invaluable support
and assistance in the field. The lizard re-
mains were kindly identified by Gregory
Pregill (San Diego Nat. Hist. Museum).
Field work was made possible in large part
by a Graduate Fellowship of the Cave Re-
search Foundation to DAM, which is grate-
fully acknowledged.
LITERATURE CITED
Asprey, C. F., and O. C. Robbins 1952. The vege-
tation of Jamaica. Ecol. Monogr. 23:359-412.
Buden, D. W. 1974. Prey remains of Barn Owls in
the southern Bahama islands. Wilson Bull. 86:336-
343.
Cramp, S. 1985. The birds of the western Palearctic,
Volume 4. Oxford University Press, Oxford. 960
pp.
Hall, E. R. 1981. The mammals of North America.
John Wiley and Sons, New York. 2 vols. 1271 pp.
Howe, H. F. 1974. Additional records of Phyllonyc-
teris aphylla and Ariteus flavescens from Jamaica. J.
Mammalogy 55:662-663.
Johnston, D. W. 1974. Food of the barn owl on Grand
Cayman, B. WI. Quart. J. Flor. Acad. of Sci. 35:171-
172.
Lack, D. 1976. Island biology; illustrated by the land
birds of Jamaica. Univ. of California Press, Berke-
ley. 445 pp.
Pregill, G. K., and S. L. Olsen 1981. Zoogeography
of West Indian vertebrates in relation to Pleisto-
cene climatic cycles. Ann. Rev. Ecol. Syst. 12:75-
98.
Schwartz, O. A., and V. C. Bleitch, 1985. Optimal
foraging in barn owls? Rodent frequencies in diet
and fauna. Bull. S. Cal. Acad. Sci. 84:41-45.
Wadge, G., A. G. Fincham, and G. Draper, 1979. The
caves of Jackson’s Bay and the Cainozoic geology
of southern Jamaica. Trans. Br. Cave Res. Assoc.
6:70-84.
Wetmore, A., and B. H. Swales, 1931. The birds of
Haiti and the Dominican Republic. Bull. U.S. Natl.
Mus. #155.
Williams, E. E. 1952. Additional notes on fossil and
subfossil bats from Jamaica. J. Mammalogy 33:171-
1 7 9 .
Accepted: 14 February 1989


The Prey of Common Barn Owls (Tyto alba) in Dry Limestone Scrub Forest of Southern Jamaica

Scholarship@Claremont

Claremont CollegesScholarship @ ClaremontWM Keck Science Faculty Papers W.M. Keck Science Department1-1-1989The Prey of Common Barn Owls (Tyto alba) inDry Limestone Scrub Forest of Southern JamaicaDonald A. McFarlaneClaremont McKenna College; Pitzer College; Scripps CollegeKimball L. GarrettThis Article is brought to you for free and open access by the W.M. Keck Science Department at Scholarship @ Claremont. It has been accepted forinclusion in WM Keck Science Faculty Papers by an authorized administrator of Scholarship @ Claremont. For more information, please contactscholarship@cuc.claremont.edu.Recommended CitationMacFarlane, D.A., and K. L. Garret. "The prey of common barn owls (Tyto alba) in dry limestone scrub forest of southern Jamaica."Caribbean Journal of Science 25 (1989): 21-23.Caribbean Journal of Science, Vol. 25, No. 1-2, 21-23, 1989Copyright 1989 College of Arts and SciencesUniversity of Puerto Rico, MayaguezThe Prey of Common Barn-Owls (Tyto alba) in Dry LimestoneScrub Forest of Southern JamaicaD O N A L D  A .  MC F A R L A N E 1 A N D  K I M B A L L  L. GA R R E T T21Section of Mammalogy, Natural History Museum of Los Angeles County,Los Angeles, California 90007, and2Section of Birds, Natural History Museum of Los Angeles County,Los Angeles, California 90007ABSTRACT . – A collection of common barn-owl (Tyto alba Scopoli) pellets from caves on the PortlandRidge of Jamaica reveals that whereas introduced rodents constitute approximately 90% of the total prey,bats and birds are also frequent prey items. Of the bats, frugivorous species predominate with Ariteusflavescens Gray and Artibeus jamaicensis Leach accounting for the largest portion of the bat prey. Insec-tivorous bats are markedly under-represented with respect to the known diversity of insectivorous speciesin the habitat.INTRODUCTIONThe prey of barn-owls on Caribbean is-lands is of special interest because of thecontribution that owl-pellet accumulationshave made to the palaeontological record(Pregill and Olson, 1981), and because owlpellets provide faunal samples in areaswhich may otherwise be poorly known inthis respect. Modern owl-pellet accumu-lations have been reported from GrandCayman (Johnston,  1974) ,  Hispaniola(Wetmore and Swales, 1931), and thesouthern Bahamas (Buden, 1974). Thesestudies have suggested that the relativelydepauperate small mammal faunas of theBahamian and Antillean islands may haveforced a degree of dietary shift upon islandowl populations. Recently, Schwartz andBleitch (1985) have provided evidencewhich indicates that the proportions of preytaxa in barn-owl pellets collected in south-ern California reflect true prey densities,an observation which reinforces the valueof owl pellet studies.METHODSIn June of 1985, osteological material wascollected from large owl-pellet deposits onthe talus cones of two deep collapse pits,Arrow Pit and Entrance 1, Somerville Cave(Wadge et al., 1979). These caves lie in thedense coastal arid faciation of the dry lime-stone scrub forest (Asprey and Robbins,1952), close to the village of Jackson’s Bay,Clarendon Parish, Jamaica. Arrow Pit is ap-proximately 20 metres deep, and Entrance1 of Somerville Cave measures some 15metres from lip to talus slope. Both pitshave steeply overhanging walls with manyledges and alcoves frequented by barnowls.The deposits were of two types; discrete,young pellets on ledges, and very largeaccumulations of loose bone apparentlyscattered from ledges downward onto talusslopes. The size of the deposits, which atSomerville occupied an estimated floor areaof 100 m2, together with the heterogeneousdisposition of prey taxa precluded the col-lection of a truly random sample in thetime available. In practice all non-rodentcrania encountered in 10 man-hours ofsearch at the two sites were collected, to-gether with a large but partial sample ofthe rodent material. Thus the relative pro-portions of the non-rodent taxa are con-sidered to be a true representation of theirproportions at the sites, but the proportionof rodent to non-rodent specimens is biasedin favor of non-rodents. Specimen num-bers are given as minimum number of in-dividuals (MNI) since crania and mandi-bles were always disassociated.22 D. A. McFARLANE AND K. L. GARRETTTABLE 1. Vertebrate prey taxa from owl-pellet de-posits at Jackson’s Bay.Mini- % ofmum # non-of indi- rodentTaxon viduals totalMammalia; RodentiaRattus rattus (L.) 900-950Mus musculus (L.) 20-25Mammalia; ChiropteraArtibeus jamaicensis (Leach) 16Ariteus flavescens (Gray) 22Erophylla sezekorni (Gundlach) 8Monophyllus redmani (Leach) 2Eptesicus lynni (Shamel) 4AvesIcterus leucopteryx (Wagler) 3Vireo altiloquus (Vielliot) 4Coccyzus sp. (americanus?) 3Tiaris olivacea (L.) 3Tyrannus sp. (dominicensis?)(Lacepede) 4Loxigilla violacea (L.) 7Dumetella carolinensis (L.) 1Myiarchus sp. (Stolidus?)(Cabanis) 1Unidentified 2ReptiliaAnolis garmani (Stejneger) 219.526.89.72.44.83.64.83.63.64.88.51.21.22.42.4RESULTSSeventeen taxa of vertebrates were iden-tified from the Jackson’s Bay collections,which were dominated by the remains ofthe introduced rat Rattus rattus Linnaeus.Of the non-rodent prey items, 63.4% werebats, 34. 1% were birds, and 2.4% were liz-ards. Table 1 lists the species identifica-tions together with the minimum numberof individuals represented.D ISCUSSIONThe only native rodent currently extanton Jamaica is Geocapromys brownii Chap-man, whose adult size (1000-2000 g) makesit an unlikely prey item for barn-owls. Geo-capromys brownii is known from the Jack-son’s Bay caves but not from owl-pelletmaterial. The black rat, Rattus rattus, is byfar the dominant prey item at both ArrowPit and Somerville Cave. An estimated 90%of the total prey items at these sites wereR. rattus. The house mouse, Mus musculusLinnaeus, was quite scarce in the depositsand accounted for no more than 2% of thetotal prey items. These figures comparewith 87.5% and 3.9%, respectively, for pel-lets collected at Morne La Viste, Haiti, byWetmore and Swales (1931).Five species of bats were identified fromthe Jackson’s Bay collections. The selectionof bat prey by the owls is apparently un-related to prey size, since the commonestprey species (Ariteus flavescens, 12 g, MNI= 22) is very close to the size of the twoleast common prey species (Eptesicus lynni,12 g, MNI = 4; Monophyllus redmani, 12 g,MNI = 2) whereas the second commonestprey species (Artibeus jamaicensis, 35 g, MNI= 16) is at least three times as large. Anotherlarge species, Erophylla sezekorni, (35 g, MNI= 8) was also represented. It is interestingto note that the three commonest preyspecies are all frugivores, although E r o -phylla takes significant quantities of flow-ers and nectar also. It is possible that theslow flight of these species and their pre-dictable occurrence at fruiting trees ren-ders them more vulnerable to aerial pre-dation.Ariteus flavescens is know from only tworecent literature records of the living an-imal ,  one of  s ix  specimens from the“Kingston area” (Williams, 1952) and oneof three specimens from Hector’s River,Portland Parish (Howe, 1974). Additionalspecimens from Kingston (D. L. Harrison,pers. comm.) and “St. Thomas” (BritishMuseum, Natural History) are also known.Since these localities are all relatively me-sic, the fact that Ariteus is apparently a com-mon species in the dry limestone scrub ofJackson’s Bay implies that it is probablywidely distributed across the island.Eptesicus lynni is also known from veryfew literature records (Hall, 1981). The re-covery of at least four individuals fromJackson’s Bay implies that this species alsomay be more widely distributed than hashitherto been supposed. The insectivorousbat Macrotus Waterhouse Gray was collectedalive from Jackson’s Bay during this field-work, but is not represented in the owl-pellet material. It is unlikely that these arePREY OF JAMAICAN OWLS 23the only two of Jamaica’s 13 insectivorousbats to occur in this habitat.The numbers of avian prey do not sug-gest any particular specialization by theowls, but probably reflect local speciesabundances. Lack (1976) regards only Du-metella carolinensis as scarce in PortlandRidge habitat. A tendency for avian preyof barn-owls to consist of communally-roosting species has been noted (Cramp,1985); of the avian prey species in thisstudy, only the grassquits (Tiaris) and per-haps the bullfinch (Loxigilla) might be con-sidered communually-roosting species.The lizard Anolis garmani is clearly un-der-represented with respect to its’ abun-dance at Jackson’s Bay, suggesting that owlpredation is not important for this species.The diversity of bat species representedin the owl-pellet accumulations providesa minimum estimate of species richness inthe bat community of Jamaican dry scrubforest. The predominance of Ariteus flaves-cens, a bat which is rare in museum col-lections taken from the island, suggests thateither the status of this species has beenseriously underestimated or that it is dis-proportionately vulnerable to barn-owlpredation. The marked under-representa-tion of insectivorous bats in the owl pelletssuggests that it would be unwise to usethese deposits alone to reconstruct a wholebat fauna.Acknowledgments. — We are indebted toRichard E. Gledhill for invaluable supportand assistance in the field. The lizard re-mains were kindly identified by GregoryPregill (San Diego Nat. Hist. Museum).Field work was made possible in large partby a Graduate Fellowship of the Cave Re-search Foundation to DAM, which is grate-fully acknowledged.LITERATURE CITEDAsprey, C. F., and O. C. Robbins 1952. The vege-tation of Jamaica. Ecol. Monogr. 23:359-412.Buden, D. W. 1974. Prey remains of Barn Owls inthe southern Bahama islands. Wilson Bull. 86:336-343.Cramp, S. 1985. The birds of the western Palearctic,Volume 4. Oxford University Press, Oxford. 960pp.Hall, E. R. 1981. The mammals of North America.John Wiley and Sons, New York. 2 vols. 1271 pp.Howe, H. F. 1974. Additional records of Phyllonyc-teris aphylla and Ariteus flavescens from Jamaica. J.Mammalogy 55:662-663.Johnston, D. W. 1974. Food of the barn owl on GrandCayman, B. WI. Quart. J. Flor. Acad. of Sci. 35:171-172.Lack, D. 1976. Island biology; illustrated by the landbirds of Jamaica. Univ. of California Press, Berke-ley. 445 pp.Pregill, G. K., and S. L. Olsen 1981. Zoogeographyof West Indian vertebrates in relation to Pleisto-cene climatic cycles. Ann. Rev. Ecol. Syst. 12:75-98.Schwartz, O. A., and V. C. Bleitch, 1985. Optimalforaging in barn owls? Rodent frequencies in dietand fauna. Bull. S. Cal. Acad. Sci. 84:41-45.Wadge, G., A. G. Fincham, and G. Draper, 1979. Thecaves of Jackson’s Bay and the Cainozoic geologyof southern Jamaica. Trans. Br. Cave Res. Assoc.6:70-84.Wetmore, A., and B. H. Swales, 1931. The birds ofHaiti and the Dominican Republic. Bull. U.S. Natl.Mus. #155.Williams, E. E. 1952. Additional notes on fossil andsubfossil bats from Jamaica. J. Mammalogy 33:171-1 7 9 .Accepted: 14 February 1989

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The Prey of Common Barn Owls (Tyto alba) in Dry Limestone Scrub Forest of Southern Jamaica

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