Variation in Survival and Harvest Rates in Florida Mottled Duck

Abstract

The Florida mottled duck (Anas fulvigula fulvigula) inhabits a relatively small range of approximately 90,000 km 2 within peninsular Florida, USA, and is threatened by habitat loss and genetic introgression with feral mallards (Anas platyrhynchos). Moreover, the Florida mottled duck population status has not been assessed for more than a decade. We used band-recovery and recapture data from 2000-2013 to examine geographic and demographic factors that influence the survival of Florida mottled ducks and to determine whether survival and harvest probabilities have changed over time. Mean survival probabilities were higher for birds banded in the southern portion of their Florida range than for those banded in the northern portion and higher for adult males than for adult females in both areas. Harvest probabilities increased in the northern extent of its range in Florida for adults and juveniles and remained relatively constant in the southern portion of its range during the study period. Mean harvest probabilities for adult males in both areas were higher than for adult females. Mean harvest probability for juvenile females was higher than that for juvenile males in the north but was similar between the sexes in the south. Our results suggest that mortality rates are generally greater in the northern portion of the Florida mottled duck range because of regional differences in habitat distribution and permanence and in how mottled ducks and humans use wetlands in these areas. We suggest increasing conservation efforts in the north portion of the Florida mottled duck range and improving inferences from leg banding by incorporating live recapture data.

Temporal variation and landcover influence survival in adult female mottled ducks

“…Annual survival estimates (including the results of the worst‐case scenario analysis) of 0.41–0.64 were similar to survival rates reported from studies using band recovery analysis across the mottled duck range (Table 5; Haukos 2015, McClinton et al 2019, Bielefeld et al 2020, Kneece et al 2020). The lowest annual survival estimate in the Texas Chenier Plain occurred during extreme drought (Moon et al 2017), whereas most periods during this study were characterized by average to moderate moisture, except for a brief period in May–August 2018 that was of moderate drought (NOAA 2021 b ).…”

Breeding Ecology of Mottled Ducks: A Review

“…Perhaps the management of mottled ducks needs to be focused on the local scale, as opposed to the regional scale. For example, differing harvest pressure, land use, and habitat conditions in north and south Florida have resulted in different survival and harvest rates (Bielefeld et al 2020), which is also likely the case for reproductive parameters.…”

Mottled Duck introductions to South Carolina: The ugly, the bad, and the good?

“…Florida Mottled Ducks historically have exploited thousands of ponds and irrigation reservoirs associated with ranching, farming, and citrus production inland and other suburban and urban areas (Bielefeld & Cox, 2006 ). Further south near Lake Okeechobee, Mottled Ducks use storm‐water treatment areas and permanent marshes of the Everglades (Bielefeld, 2008 , 2011 ). The West‐Gulf Coast Mottled Ducks also use freshwater wetlands, ditches, canals, and ricefields, but some birds in the West‐Gulf Coast and South Carolina seek intermediate and brackish wetlands (Baldassarre, 2014 ; Grand, 1988 ; Shipes et al, 2015 ; Zwank et al, 1989 ).…”

“…The Mottled Duck is an iconic waterfowl species in North America, important to conservationists that include hunters, birders, and general laity (Bielefeld et al, 2020;Lavretsky et al, 2021), and thus is emblematic of such debate. The Mottled Duck is part of an Anatid complex which also includes the American Black Duck (Anas rubripes), Mallard (A. platyrhynchos) and the Mexican Duck (A. diazi) in North America (Bellrose, 1980;Lavretsky et al, 2014;McCracken et al, 2001).…”