No abstract

An understanding of survival and underlying causes of mortality is essential to the development of effective management strategies for the mottled duck (Anas fulvigula) in Florida. From radiotelemetry data we estimated season‐specific survival rates for the entire annual cycle, cause‐specific mortality rates, and annual survival rates. We also tested for variation in survival in relation to year and period of the annual cycle. Our results suggest a strong temporal influence on survival of adult female mottled ducks, both within and among years. We found variation among years in the influence of various mortality agents, with alligators (Alligator mississippiensis), raptors, mammals, and human hunters being the principal mortality factors. Our results also suggest a link between surface water conditions within the Upper St. Johns River Basin (USJRB) and surrounding areas and survival. Agencies managing water and wildlife should be aware of this relationship and consider potential detrimental effects to mottled duck survival. (WILDLIFE SOCIETY BULLETIN 34(2):388–394; 2006)

No abstract

Florida will continue to undergo high rates of habitat loss, primarily the result of urbanization. In addition, invasive species are a major threat to Florida's biodiversity. The Florida mottled duck (Anas fulvigula), a bird unique to the state, is particularly vulnerable to loss of wetland habitats and hybridization with feral mallards. Because mottled ducks are more likely to encounter feral mallards in urban habitats, we trapped and radiomarked adult females in urban (n = 99) and rural (n = 146) habitats to estimate home ranges and rates of movement into and out of urban areas. We also determined habitat use in urban and rural areas during the breeding (1 Feb–31 Jul), post‐breeding (1 Aug–18 Nov), and hunting (19 Nov–31 Jan) periods and estimated seasonal habitat selection of rural female mottled ducks. Urban females used mostly aquatic habitats in low and high intensity human development year‐round. Rural ducks used freshwater marshes throughout the year, but selection of other habitat types varied seasonally. Use of glades marsh and agricultural habitats by rural ducks peaked during the breeding season. Rural ducks selected artificial impoundments and reservoirs during the post‐breeding and hunting periods. Median home range size of rural females was more than 65 times greater than those of urban females. Our results suggest the spread of mallard genetic introgression caused by females leaving urban areas may be slow because as few as 6% of the adult females moved between urban and rural areas. Focusing wetland conservation efforts on freshwater marshes and artificial impoundments in south Florida would likely benefit mottled ducks. © 2014 The Wildlife Society.

Habitat loss has negatively affected many species of upland‐nesting waterfowl. Very few areas contain pristine nesting habitat in Florida because of conversion to agriculture and urban development. Although some species have acclimated to nesting in an altered landscape, little is known about the nesting ecology of Florida mottled ducks (Anas fulvigula fulvigula) that use altered habitats. We located and monitored 77 nests of radio‐marked Florida mottled ducks in the Upper St. Johns River Basin (1999–2002) and in south Florida (2009–2011) and tested the effects of nest vegetation characteristics, human disturbance, and temporal variables on estimates of daily nest survival. We also calculated the percent of females that nested each year as a measure of breeding propensity. Nest age at discovery had a positive relationship with daily nest survival. Daily nest survival rates did not vary within or among years and were unaffected by density and height of vegetation at the nest and human disturbance parameters we measured. Breeding propensity ranged from 25% to 56%. Breeding propensities were less than those of other duck species, but our nest success estimate of 28% was greater than most estimates for ducks and is not likely to limit population growth of Florida mottled ducks. © 2013 The Wildlife Society.