After a year of waiting, the paper that I wrote with Justin and John is finally published! This is a journal article that arose from an accidental encounter with a juvenile Barn Owl in a small cave that I noticed on the side of a trail we were on while exploring the Hellshire Hills. This southern region of Jamaica is not one in which we expected to see the Golden Swallow, but we wanted to check anyway, as well as look out for some of the rare tropical dry scrub species we might find in the area, like the Jamaican Iguana, previously thought extinct.
I briefly hinted at this paper in an old post after our return from Jamaica, but didn’t mention it after that since I knew a published article would tell the story more fully, albeit more technically and with science instead of storytelling as a priority. In the cover photo above I’ve included a link to the PDF version of Caribbean Naturalist journal issue 37, which contains our article, but I also want to summarize our findings in lay terms for those less familiar with the biological jargon.
While looking for the critically endangered Jamaican Golden Swallow in the Hellshire Hills, the three of us stumbled upon a small limestone cavity off the dirt trail we were hiking, and went to explore it, since caves can be important roosting or nesting sites for swallows. Instead of the birds we were looking for, we found a dusty space filled with moth wings. We stepped inside to see what might be responsible for such strange litter, and startled a juvenile Barn Owl, which promptly ran into a short tunnel where it was safe from our reach – and where I took the photograph above. Later research in Barn Owl indicated that this juvenile was around a month and a half old.
Not wishing to disturb the young owlet further, we collected some of the old moth wings to try and identify them later, and also grabbed some owl pellets and other prey remains that were outside the cave entrance. Owl pellets are little balls of fur, feathers, and bones that owls regurgitate after digesting whatever possible of their predominantly rodent prey; other prey remains in this case would be rat and mice skulls loosely congregated around a perch (sometimes Barn Owls will decapitate their prey before swallowing it whole).
The moth wings turned out to belong to a species known as the Black Witch Moth, a common enough lepidopteran in North America and elsewhere.
The main reason we chose to write an article about our findings and submit them to a peer-reviewed journal is that, after a good deal of research in the Cornell libraries and online, I couldn’t find much evidence for insects being recorded as a significant prey source for Barn Owls. Smaller species of owls eat insects all the time, and Barn Owls are known to go for large insects as well, but not so much with moths in particular, and possibly not on this scale either. Our guess as to why such levels of moth-eating hadn’t been recorded in Barn Owls much is that since most diet studies for owls rely on analysis of pellets like those pictured above, where bones are conveniently packaged in balls of fur and feathers, the softer exoskeletons of insects might not make recognizable samples for someone not trained in identifying bits of bug. There also simply isn’t that much research on Barn Owls in the Caribbean.
Interestingly, certain ornithologists had written about higher amounts of insectivory in arid regions, especially islands, but most people researching Barn Owls seemed to share the sentiment of one group of authors from England who wrote that invertebrates represented “ludicrously insignificant [prey] species” for these big owls. Our argument is that perhaps young Barn Owls eat more insects, since they can be easier to catch, and we want to encourage more research into the owls’ dietary habits to be sure that insects are not being missed, since scientists often use only pellets to determine what is being eaten. In fact, in some regions Barn Owl pellets can be a good measure of what species of rodents are around, and how many, but if insect remains are harder to spot in pellets, our understanding of Barn Owl diet may be inaccurate.
In addition to encouraging more research on Barn Owls in the tropics, we also wanted to highlight the Hellshire Hills, an area threatened by limestone mining, deforestation, and invasive species. The Hellshires are known as a biodiversity hotspot within the biologically diverse island of Jamaica, and are the only remaining natural habitat for the Jamaican Iguana, which was thought extinct between the 1940s and 1990. The fact that a substantially large reptile went unnoticed for half a century prior to being rediscovered speaks to both the isolated nature of the Hellshire Hills and the lack of research carried out in the region. Although environmental interest is starting to increase, the future of the Hellshire Hills’ biodiversity would strongly benefit from greater attention from the scientific and conservation communities.