The Influence of Tide, Wind, and Habitat on the Abundance and Foraging Rate of Three Species of Imperiled Plovers in Southwest Florida, USA.

Piping Plover (Charadrius melodus), Snowy Plover (Charadrius nivosus), and Wilson's Plover (Charadrius wilsonia) are imperiled species that overlap in both their range and habitat outside the breeding season. The purpose of this research was to document the abundance of these species at a barrier island in Southwest Florida, USA, and to examine the influence of tide and wind on both their abundance and foraging. We walked ~700 m surveys through tidal mudflat and adjacent beach semiweekly at 0730-1030 from 24 September 2021-4 March 2022. During these 38 surveys, Piping Plovers were the most abundant of the three species, and the average number counted was 34 (SD 17.3) compared with 11 (SD 6.3) Snowy Plovers and 14 (SD 14.1) Wilson's Plovers. All of the species were more likely to be found on the mudflats during low tides and the beach during high tides. Our findings suggest the high densities of Piping, Snowy, and Wilson's Plover are due to a mudflat habitat that provides high availability of prey, a beach habitat that provides a relatively safe location to roost, and the context of the barrier island, which is surrounded by other suitable habitats. While each species used the barrier island's habitats slightly differently, the high densities of all three species present an opportunity to have a large conservation impact by protecting this dynamic area.

The Role of Fishing Piers in Brown Pelican (Pelecanus occidentalis) Entanglement.

Throughout their range, Brown Pelicans (Pelecanus occidentalis) are one of the most common species to become entangled in fishing gear. We surveyed four piers every other week for one year (6/2019−5/2020) in the Tampa Bay region, FL, USA, to determine frequency of pelican entanglement associated with fishing piers, and explored factors that might influence the rate of entanglement. We conducted a generalized linear model (GLM) to determine the influence that pier, pier closure due to COVID-19, time of day and season, number of anglers, and presence of human behaviors that might attract pelicans to the pier had on the number of entangled pelicans. We conducted 144 surveys and counted 3766 pelicans of which 254 (7%) were entangled. The variables significantly associated (p < 0.05) with entanglement were the pier, time of day, and pier closure status, while the number and behavior of anglers were not significant. The two piers that most significantly influenced the number of entanglements both had extensive perches within 10 m of the fishing pier. The management action most likely to reduce the number of entangled pelicans appears to be deterring pelicans from perching near piers or decreasing fishing near perching structures.

Heavy Rainfall, Sewer Overflows, and Salmonellosis in Black Skimmers (Rynchops niger).

Extreme weather events, particularly heavy rainfall, are occurring at greater frequency with climate change. Although adverse human health effects from heavy rainfall are often publicized, impacts to free-ranging wildlife populations are less well known. We first summarize documented associations of heavy rainfall on wildlife health. We then report a novel investigation of a salmonellosis outbreak in a colony of black skimmers (Rynchops niger) in Florida, USA. During June-September 2016, heavy rainfall resulted in the discharge of millions of gallons of untreated wastewater into the Tampa Bay system, contaminating the water body, where adult skimmers foraged. At least 48 fledglings died, comprising 39% of the colony's nesting season's offspring. Of eight examined deceased birds from the colony, six had a systemic salmonellosis infection. Isolates were identified as Salmonella enterica serotype Typhimurium. Their pulsed-field gel electrophoresis patterns were identical to each other and matched those from several human Salmonella sp. infections. Differences among whole-genome sequences were negligible. These findings and the outbreak's epidemic curve suggest propagated transmission occurred within the colony. A multidisciplinary and One Health approach is recommended to mitigate any adverse effects of climate change-driven stochastic events, especially when they place already imperiled wildlife at further risk.

Depth dependent variation of the echolocation pulse rate of bottlenose dolphins (Tursiops truncatus).

Trained odontocetes appear to have good control over the timing (pulse rate) of their echolocation clicks; however, there is comparatively little information about how free-ranging odontocetes modify their echolocation in relation to their environment. This study investigates echolocation pulse rate in 14 groups of free-ranging bottlenose dolphins (Tursiops truncatus) at a variety of depths (2.4-30.1 m) in the Gulf of Mexico. Linear regression models indicated a significant decrease in mean pulse rate with mean water depth. Pulse rates for most groups were multi-modal. Distance to target estimates were as high as 91.8 m, assuming that echolocation was produced at a maximal rate for the target distance. A 5.29-ms processing lag time was necessary to explain the pulse rate modes observed. Although echolocation is likely reverberation limited, these results support the hypotheses that free-ranging bottlenose dolphins in this area are adapting their echolocation signals for a variety of target detection and ranging purposes, and that the target distance is a function of water depth.