Faculty Scholarship 2019 Time-activity Budgets of Stiff-tailed Ducks in Puerto Rico Nickolas S. Goodman Jack C. Eitniear James T. Anderson Follow this and additional works at: https://researchrepository.wvu.edu/faculty_publications Part of the Animal Sciences Commons Global Ecology and Conservation 19 (2019) e00676 Contents lists available at ScienceDirect Global Ecology and Conservation journal homepage: http://www.elsevier.com/locate/gecco Original Research Article Time-activity budgets of stiff-tailed ducks in Puerto Rico * Nickolas S. Goodman a, 1, Jack C. Eitniear b, James T. Anderson a, a School of Natural Resources, West Virginia University, P.O. Box 6125, Morgantown, WV, 26506, USA b Center for the Study of Tropical Birds, Incorporated, 218 Conway Drive, San Antonio, TX, 78209, USA article info abstract Article history: Habitat loss and degradation have contributed to declining populations of stiff-tailed ducks Received 22 February 2019 including the migratory northern ruddy duck (Oxyura jamaicensis rubida), and non- Received in revised form 20 May 2019 migratory masked duck (Nomonyx dominicus) and West Indian ruddy duck (Oxyura j. Accepted 20 May 2019 jamaicensis). Studies collecting time-activity budgets on waterfowl can provide important insight into habitat use, behavior, and niche partitioning. Even though the northern ruddy Keywords: duck and West Indian ruddy duck are recognized as the same species, we treated them Laguna Cartagena National Wildlife refuge separately to appraise possible ecological differences. We recorded 24-h time-activity Masked duck ¼ ¼ Northern ruddy duck budgets for masked ducks (n 142), northern ruddy ducks (n 1,401), and West Indian ¼ Time-activity budgets ruddy ducks (n 3,765) on the Laguna Cartagena National Wildlife Refuge in Lajas, Puerto Waterfowl behavior Rico from January through April 2015 and 2016. Behaviors varied among taxa, between West Indian ruddy duck sexes, and between diurnal and nocturnal sampling periods. Resting and sleeping were common behaviors observed during the day and night, but all 3 taxa fed more at night with masked duck feeding more than the West Indian ruddy duck and northern ruddy duck. Northern ruddy duck and West Indian ruddy duck time-activity budgets varied with 7 of 8 behavioral categories during the day and 5 of 8 behavioral categories at night differing. Ecological differences such as body size and migration of northern ruddy ducks may account for the differences in behavior when compared to non-migratory West Indian ruddy ducks. © 2019 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/). 1. Introduction Masked ducks (Nomonyx dominicus) are rare, small, secretive birds with little known about them compared to other stiff- tailed ducks (Johnsgard and Carbonell, 1996). They inhabit small, shallow, ephemerally-flooded lakes and ponds covered with thick emergent and floating vegetation, and range from eastern South America north into the southern United States (Eitniear and Colon-Lopez, 2005; Johnsgard and Carbonell, 1996; Lockwood, 1997; Todd, 1996). The species is widespread throughout South and Central America; however, their population densities are low and unstable in most regions. Although there is a world population estimate of 10,000 ducks (Callaghan and Green, 1993), there is limited confidence in this estimate due to their nomadic tendencies (Johnsgard and Carbonell, 1996) and elusive behavior (Madge and Burn, 1988). Masked ducks are considered endangered in Puerto Rico and a species of concern in the Caribbean (Baldassarre, 2014). To adequately conserve this species we need detailed life history information, which currently is lacking (Eitniear, 2014). The species is widely hunted * Corresponding author. School of Natural Resources, West Virginia University, PO Box 6125, Morgantown, WV, 26506, USA. E-mail address: [email protected] (J.T. Anderson). 1 Current affiliation: Natural Resources Conservation Service, 5401 Old Redwood Hwy N, Petaluma, CA, 94954, USA. https://doi.org/10.1016/j.gecco.2019.e00676 2351-9894/© 2019 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/ licenses/by-nc-nd/4.0/). 2 N.S. Goodman et al. / Global Ecology and Conservation 19 (2019) e00676 (Eitniear, 2014) and past and predicted future wetland loss and degradation from agriculture, deforestation, hydropower activity, mining, and climate change are likely to have profound impacts on available habitat for this species (Junk, 2013; Junk et al., 2013; Mitsch and Hernandez, 2013). Northern Ruddy ducks (Oxyura jamaicensis rubida) are commonly harvested stiff-tailed ducks found in North America, Central America, and the Caribbean that have been extensively studied compared to masked ducks (Baldassarre, 2014). There is also a non-migratory ruddy duck found in Puerto Rico known as the West Indian ruddy duck (Oxyura j. jamaicensis)(Danforth, 1926; Molinares, 1981; Dickinson and Remsen, 2013). Currently the 2 taxa of ruddy duck are not formally recognized as separate species, but they are recognized as separate races (Dickinson and Remsen, 2013). The migratory northern ruddy duck is closely related to the nonmigratory West Indian ruddy duck (Bellrose, 1978). The West Indian ruddy duck was originally described as a new species by Danforth (1926); it has a shorter tail and wings along with a longer tarsus compared to the northern ruddy duck. As indicated above most taxonomic authorities now consider the West Indian ruddy duck and the northern ruddy duck as separate races, but not separate species. Although these differences are only visible with careful measurements when ducks are in hand, the 2 taxa can be separated at a distance by looking at the male's cheeks (Danforth, 1926; Molinares, 1981; Raffaele et al., 1998). Male West Indian ruddy duck has black and white on their cheeks (Danforth, 1926; Molinares, 1981), whereas the male northern ruddy duck only has white cheeks (Johnsgard, 1978). Females of the 2 taxa are only distinguishable from each other in hand by taking measurements of the tail, wings, and tarsus, but they flock with their own taxa so they can be distinguished by looking at the males around them (Molinares, 1981). In this study, we treat these taxa as separate species to see if they have ecological differences aside from being migratory versus non-migratory. Ruddy ducks are expanding their range in the Caribbean (Brown and Collier, 2004) and could potentially impact the less abundant masked duck (J. Eitniear personal communication). Indeed, white-headed ducks (Oxyura leucocephala), a globally threatened species, have declined substantially due to hybridization with the ruddy duck (Hughes et al., 2006). Comparative studies are needed to determine the potential impacts of an expanding ruddy duck population on masked ducks to ensure that the same fate impacting white-headed ducks does not befall masked ducks. Studies collecting time-activity budgets on waterfowl have provided important insight into habitat use (Poulton et al., 2002; Michot et al., 2006; Crook et al., 2009), foraging (Tatu et al., 2007), and niche partitioning (Titman, 1981; Rave and Baldassarre, 1989). Because of niche partitioning among taxa of ducks, comparative studies of multiple taxa on the same waterbody are of conservation and management interest, but are seldom performed (White and James, 1978). Masked duck, northern ruddy duck, and West Indian ruddy duck occur on the Laguna Cartagena National Wildlife Refuge (NWR) in Lajas, Puerto Rico, and thus create a unique opportunity to conduct a simultaneous time-activity budget study. There has been no research comparing time-activity budgets of these 3 taxa. Also, there have been no time-activity budgets collected on the masked duck or West Indian ruddy duck and none collected for the northern ruddy duck in Puerto Rico, although these data would be beneficial for species conservation. Simultaneously collecting time-activity budgets on these 3 closely related taxa will: (1) show how they interact with each other; (2) provide insight into how they spend their time; (3) allow for speculation of dietary and energy needs; and (4) acquire new information to be used for management of the waterfowl and Laguna Cartagena (Adams et al., 2000; Crook et al., 2009). Our objective was to compare diurnal and nocturnal time-activity budgets of masked duck, West Indian ruddy duck, and northern ruddy duck. 1.1. Study area The study area was the 422-ha Laguna Cartagena NWR in Lajas, Puerto Rico (18 000 40.100 N, 67 060 10.100 W). Our ob- servations occurred on the 80-ha lagoon, which is all that remains of a once larger lagoon (USFWS, 2011). About 50% of the lagoon was dominated by cattail (Typha domingensis) with the remainder being open water with small patches of sedges (Cyperus spp.) and floating vascular plants (water lettuce [Pistia stratiotes] and water hyacinth [Eichhornia crassipes]) (Sanchez-Col on, 2012, 2015). Water depth ranged from 0 to 200 cm during the study period (Goodman et al., 2018). The lagoon occasionally dries and cattail control is performed (USFWS, 2011). There is a dike that goes about halfway across the lagoon like a peninsula, but the lagoon is one continuous cell. Historically, about half of all breeding bird species in Puerto Rico were observed in the area and it was an important stopover point for migrating waterfowl (USFWS, 2011). There have been 144 bird species documented on the refuge, including 18 endemic species and sub-species of birds, 2 of which are endangered (USFWS, 2011). There are 4 native mammal (all bats), 11 reptile, 5 amphibian, 18 fish, and over 500 plant species documented on Laguna Cartagena NWR (USFWS, 2011). West Indian whistling ducks (Dendrocygna arborea)(Goodman et al., 2018) and ruddy ducks (USFWS, 2011) are among the most common waterfowl species on the refuge. An 8-m tall wooden observation tower on the south-central side of the lagoon provided a good view of the entire lagoon.