Allan O'Connell, Jr., Ph.D. (Former Employee)
Science and Products
Mammals
Our science portfolio includes the study and management of mammal populations, which can require the use of methods and analysis that incorporate the difficulty in detecting them – picture how hard it is to count and identify bats at dusk or estimate the number of mountain lions in an area.
Invasive Species
The impact of invasive plants and animals as taken on a heightened significance with an increase in the movement of people and goods around the world. Control of invasive and non-native species has become a national priority in the protection of endangered species and ecosystem services (through native species) and the understanding the mechanisms, pathways, and ecological relationships is...
Occupancy
Many wildlife studies seek to understand changes or differences in the proportion of sites occupied by a species of interest. These studies are hampered by imperfect detection of these species, which can result in some sites appearing to be unoccupied that are actually occupied. Occupancy models solve this problem and produce unbiased estimates of occupancy (ie, occurrence) and related...
Capture-Mark-Recapture Science
Capture-Mark-Recapture (CMR) can be viewed as an animal survey method in which the count statistic is the total number of animals caught, and the associated detection probability is the probability of capture. The method involves capturing a number of animals, marking them, releasing them back into the population, and then determining the ratio of marked to unmarked animals in the population...
Assessing Endangered Marsh Rabbit and Woodrat Habitat use and Predator Population Dynamics
Feral and free-ranging domestic cats (Felis catus) have strong negative effects on wildlife, particularly in island ecosystems such as the Florida Keys. We deployed camera traps to study free-ranging cats in National Wildlife Refuges and state parks on Big Pine Key and Key Largo and used spatial models to estimate cat population dynamics and stable isotope analyses to examine cat diets. Top...
Towards recovery of an endangered island endemic: Distributional and behavioral responses of Key Largo woodrats associated with exotic predator removal
Exotic predators create novel ecological contexts for native species, particularly when prey exhibit predator naïve behaviors. Population recovery of island endemic species following predator eradication has been documented broadly, but studies examining mammalian prey behavioral responses to exotic predator removal are less common. The Key Largo...
Cove, Michael V.; Simons, Theodore; Gardner, Beth; O'Connell, Allan F. Co‐occurrence dynamics of endangered Lower Keys marsh rabbits and free‐ranging domestic cats: Prey responses to an exotic predator removal program
The Lower Keys marsh rabbit (Sylvilagus palustris hefneri) is one of many endangered endemic species of the Florida Keys. The main threats are habitat loss and fragmentation from sea‐level rise, development, and habitat succession. Exotic predators such as free‐ranging domestic cats (Felis catus) pose an additional threat to these endangered small...
Cove, Michael V.; Gardner, Beth; Simons, Theodore R.; O'Connell, Allan F. Free-ranging domestic cats (Felis catus) on public lands: estimating density, activity, and diet in the Florida Keys
Feral and free-ranging domestic cats (Felis catus) can have strong negative effects on small mammals and birds, particularly in island ecosystems. We deployed camera traps to study free-ranging cats in national wildlife refuges and state parks on Big Pine Key and Key Largo in the Florida Keys, USA, and used spatial capture–recapture models to...
Cove, Michael V.; Gardner, Beth; Simons, Theodore R.; Kays, Roland; O'Connell, Allan F. Camera traps reveal an apparent mutualism between a common mesocarnivore and an endangered ungulate
Camera traps are commonly used to study mammal ecology and they occasionally capture previously undocumented species interactions. The key deer (Odocoileus virginianus clavium) is an endangered endemic subspecies of the Florida Keys, where it exists with few predators. We obtained a camera trap sequence of 80 photos in which a key deer interacted...
Cove, Michael V.; Maurer, Andrew S.; O'Connell, Allan F. Managing native predators: Evidence from a partial removal of raccoons (Procyon lotor) on the Outer Banks of North Carolina, USA
Raccoons (Procyon lotor) are important predators of ground-nesting species in coastal systems. They have been identified as a primary cause of nest failure for the American Oystercatcher (Haematopus palliatus) throughout its range. Concerns over the long-term effects of raccoon predation and increased nest success following a hurricane inspired a...
Stocking, Jessica J.; Simons, Theodore R.; Parsons, Arielle W.; O'Connell, Allan F. Evaluating nest supplementation as a recovery strategy for the endangered rodents of the Florida Keys
The Key Largo woodrat (Neotoma floridana smalli) and Key Largo cotton mouse (Peromyscus gossypinus allapaticola) are federally endangered subspecies endemic to the tropical hardwood hammocks of Key Largo, Florida. Woodrats are considered generalists in habitat and diet, yet a steady decline in natural stick nests and capture rates over the past...
Cove, Michael V.; Simons, Theodore R.; Gardner, Beth; Maurer, Andrew S.; O'Connell, Allan F. Obituary: Graham W. Smith (1950-2015)
O'Connell, Allan F. A hidden view of wildlife conservation: How camera traps aid science, research and management
Florida panthers are among the world’s most endangered — and elusive — animals. For approximately four decades, scientists have been researching this small population of panthers that inhabit the dense forests and swamps of south Florida. Because of their wide habitat range along with an absence of clear visual features, these...
O'Connell, Allan F. Camera traps and mark-resight models: The value of ancillary data for evaluating assumptions
Unbiased estimators of abundance and density are fundamental to the study of animal ecology and critical for making sound management decisions. Capture–recapture models are generally considered the most robust approach for estimating these parameters but rely on a number of assumptions that are often violated but rarely validated. Mark-resight...
Parsons, Arielle W.; Simons, Theodore R.; Pollock, Kenneth H.; Stoskopf, Michael K.; Stocking, Jessica J.; O'Connell, Allan F. Key seabird areas in southern New England identified using a community occupancy model
Seabirds are of conservation concern, and as new potential risks to seabirds are arising, the need to provide unbiased estimates of species’ distributions is growing. We applied community occupancy models to detection/non-detection data collected from repeated aerial strip-transect surveys conducted in 2 large study plots off southern New...
O'Connell, Allan F.; Flanders, Nicholas P.; Gardner, Beth; Winiarski, Kristopher J.; Paton, Peter W. C.; Allison, Taber Statistical guidelines for assessing marine avian hotspots and coldspots: A case study on wind energy development in the U.S. Atlantic Ocean
Estimating patterns of habitat use is challenging for marine avian species because seabirds tend to aggregate in large groups and it can be difficult to locate both individuals and groups in vast marine environments. We developed an approach to estimate the statistical power of discrete survey events to identify species-specific hotspots and...
Zipkin, Elise F.; Kinlan, Brian P.; Sussman, Allison; Rypkema, Diana; Wimer, Mark; O'Connell, Allan F. Fitting statistical distributions to sea duck count data: implications for survey design and abundance estimation
Determining appropriate statistical distributions for modeling animal count data is important for accurate estimation of abundance, distribution, and trends. In the case of sea ducks along the U.S. Atlantic coast, managers want to estimate local and regional abundance to detect and track population declines, to define areas of high and low use,...
Zipkin, Elise F.; Leirness, Jeffery B.; Kinlan, Brian P.; O'Connell, Allan F.; Silverman, Emily D.
Significant Milestone in Whooping Crane Recovery
This week marks a significant milestone in the conservation and recovery of the endangered whooping crane. On March 11 and 13, the U.S. Geological Survey’s Patuxent Wildlife Research Center transferred its last two cranes of the approximately 75 that were in its flock to other institutions, closing out more than 50 years of the center’s whooping crane research and captive breeding success.