Geology Reports⌕ Search

USGS · 1008533

Distribution patterns of individually identifiable West Indian manatees ( Trichechus manatus ) in Florida

Abstract

Photographs of distinctively scarred manatees ( Trichechus manatus ) were taken at aggregation sites throughout Florida and assembled into a catalog for identifying individuals. Resightings of known manatees in different years or at different locations enabled us to document site fidelity and long-distance movements. Of the 891 individuals included in the catalog as of August 1986, 470 (53%) were resighted at least once. We documented 219 cases of seasonal returns to specific aggregation sites and 98 instances of movements between areas. Movements in excess of 820 km were documented for individuals on the east coast of Florida. Rapid movements south during early winter, as well as northerly spring movements, verify a seasonal migration pattern for many individuals along Florida's east coast. The wide-ranging migratory habits of manatees in Florida must be considered if meaningful management strategies are to be developed and implemented.

Explore related subjects

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

J.P. Reid, G. B. Rathbun, J.R. Wilcox. 2006-08-26. Distribution patterns of individually identifiable West Indian manatees ( Trichechus manatus ) in Florida. https://doi.org/10.1111/j.1748-7692.1991.tb00564.x

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related USGS reports

Detecting polar bears on land using satellite imagery and deep learning

Summer land use is increasing for polar bears in the Beaufort Sea, which may lead to increases in human-bear interactions. Remote methods may enable noninvasive approaches to monitor polar bear abundance and distribution on land. We examined the potential of using very high-resolution optical satellite imagery to detect polar bears on land from images collected at three sites on the Beaufort Sea coast of Alaska. Additionally, we evaluated the use of deep learning models to automate detection of polar bears in these images and the degree to which detection of polar bears differed among three very high-resolution optical satellite missions. Pléiades Neo images exhibited 90% average precision in validation analyses using a faster region-based convolutional neural network model, which was 55% and 11% greater than the average precision using WorldView-2 or -3 images, respectively. Applying the Pléiades Neo training set to new imagery exhibited lower precision (35%), but high recall (100%), which indicates that deep learning could be used to expedite the visual detection of polar bears in imagery. Very high-resolution optical satellite imagery provides a remote method for monitoring polar bears on land where they occur in high densities, but satellite mission, off-nadir angle, pansharpening methods, and image resolution are important considerations.

Alaska↗

Quantifying southern sea otter (Enhydra lutris nereis) reactions to a quadcopter drone in central California

Drones are useful for wildlife research and management, but they can cause disturbance and harassment to wildlife. Sea otters ( Enhydra lutris ) are candidates for drone-based observation and monitoring but are vulnerable to disturbance. No studies have evaluated drone effects on sea otter behavior, but based on prior disturbance studies, we hypothesized: (1) sea otters would exhibit behaviors indicating higher reactivity in the presence of drones than when drones were absent and (2) drone disturbance to sea otters would be greater when drones were closer. At two sites in Monterey Bay, CA, we conducted 37 observational sessions, recording behavior codes for focal sea otters during a baseline (no drone) period and three consecutive drone flights. Data were analyzed using ANOVA and ordinal logistic regression models. At both locations, focal sea otters had higher behavior codes during drone trials compared to baseline, and behavior codes increased with descending drone altitude. Pup presence, group size, flight trial number, and gull presence were significant covariables. We calculated multipliers to predict drone-mediated behavioral responses at a range of drone altitudes. Our findings can inform best practices for a variety of uses of drones around sea otters, including population monitoring, oil spill response, and drone photography/videography.

California↗