|
Research Updates |
|
 Jason
Martin, a graduate student from the University of Florida (Dept. of
Wildlife Ecology & Conservation), is currently conducting research
to: 1) determine if Barn Owls are capable of impacting rodent
populations in the EAA, and 2) examine the ecology of the EAA Barn Owls. Preliminary data
is described on this page.
Thanks to the University of Florida-Institute of Food and Agricultural Sciences, the Florida Sugar Cane League, the Florida Ornithological Society, the Clewiston Chamber of Commerce, Florida Crystals Corp., U.S. Sugar Corp, and the Sugar Cane Growers Cooperative of Florida for their financial and logistical assistance. |
|
|
|
|
| How many Barn
Owls are there in the EAA?
|
|
| Over
the past 10-15 years, members of the EAA community have installed artificial
nest boxes to increase the regional density of Barn Owls. In spring
2005, there were 233 boxes in Palm Beach County. There were nests in
52% of these boxes, and the rest all showed signs of being used for roosting or nesting in the
recent past. In fall 2006, prior to hurricane Wilma, there were nests in 71% of the boxes; however,
most nest boxes were destroyed by the storm. The boxes are
quickly being replaced and are being re-colonized by the owls. As of
spring 2006, 85 boxes have been repaired and there are nests in 78% of
them.
(Note: All boxes are on private property and are not accessible for public viewing) |
|
|
|
|
|
|
| What types of
rodents live in the EAA?
|
|
During fall 2005, just prior to the sugar cane harvest, live-trapping surveys were conducted along sixteen 250-m sections of field ditches located throughout the EAA to find out which rodent species were present. The resulting relative indices of abundance showed that cotton rats were the most common, but the actual number of individuals present varied. The three species listed below are of most concern regarding their potential to damage sugar cane crops. |
|
 |
 |
|
|
| Which rodents are responsible for
damaging the sugar cane?
|
Individual rats of the three species of concern were placed in a cages for 24 hours with standardized sections of sugar cane stalk. The amount of cane eaten by the rats was then measured. All three species consumed sugar cane during the trials. Amazingly, some individuals ate more than 100% of their body weight in 24 hours! Because cotton rats are the most common species in the EAA, they collectively cause more damage than roof rats or rice rats. |
|
|
|
|
| Are Barn Owls eating the
pest rodents?
|
|
Barn
Owls usually swallow their prey whole, and later regurgitate
indigestible bones and fur in the form of a pellet.
These pellets can then be examined to identify what the owls
eat.
Based on an analysis of 1107 of these pellets, cotton rats, roof
rats, and rice rats comprise 56% of the diet of Barn Owls in
the EAA.
|
|
|
|
|
|
|
| So are the owls making a difference?
|
An experiment is currently underway to determine if rodent populations can be reduced by Barn Owl predation. Extremely high densities of owls are being established in several areas by installing dense clusters of nest boxes. The rodent populations in these areas are being tracked over time to see if they decline as the owls move in. Stay tuned! |
|
|
| Have you seen this owl?
|
||
| Identification leg
bands are being placed on Barn Owls to monitor their movements, nest box usage,
and longevity. To date, 286 owls have been banded (89 adults, 197
nestlings). If you
find one of these birds, please report the number on the metal band, the
colors of the plastic bands, and the location and circumstances of your
sighting to Jason Martin (martin13@ufl.edu).
Thank you!
|
||
|
|
|
|
|
|
| Barn owl nest
monitoring
|
| The
nesting activities of the EAA Barn Owls are closely monitored to determine
how many eggs are laid, the number of eggs that hatch, and the number of
hatchlings that survive to leave the nest.
|
|
|
|
|
| Juvenile dispersal
|
||
| Young
Barn Owls are banded and relocated after they leave the nest to determine
how many survive and how far they travel.
So far, 197 nestlings have been banded. 29 were found dead
in or near their parents' nests, 2 were reported dead 4 km (2.5 miles) and 8 km
(5 miles) from their
birth sites, and 2 have established nests of their own at
distances of 11 km (6.8 miles) and 16 km (9.9 miles) from their natal locations.
|
||
|
|
|
|
|
|
 |
Content and design by Jason Martin Contact: martin13@ufl.edu University of Florida / EREC Dept. of Wildlife Ecology & Conservation Photos by Jason Martin, Brian Mealey, Jeanne Parker, Ken Meyer, and the Florida Department of Agriculture and Consumer Services Last updated: 9/24/06 |
Return to EREC Home |
