Nimish Vyas, Ph.D.
I am a research biologist driven by my interest in avian conservation. My research focuses primarily on identifying and addressing threats to birds and their environments that arise from human ignorance and arrogance. My current work falls under ecotoxicology and invasive species research categories but my interests also encompass a myriad of other anthropogenic hazards to birds (for example, energy development, light pollution, avian trafficking and poaching, and illegal killings). Much of my research produces publications with real-world applicability. These publications have the unique property of direct implementation for avian conservation in the field. Therefore, the publications have been used by natural resource managers, policy regulators, wildlife law enforcement agents, and U.S. Attorneys.
- B.S. 1986, University of Maryland
- Ph.D. 1992, University of Maryland
- Biologist 1989-1992, US Environmental Protection Agency.
- Research Biologist 1992-current, USGS Patuxent Wildlife Research Center
- Instructor 1995- current, US Fish and Wildlife Service's National Conservation Training Center course 'Pesticides and Fish and Wildlife Resources'.
- Adjunct Associate Professor, Department of Poultry Science, University of Maryland, College Park, Maryland, USA. 1996- 1998.
- Adjunct Professor, Department of Animal and Avian Sciences, University of Maryland, College Park, Maryland, USA. 1998-2000.
- Co-professor for an undergraduate/graduate course, Ornithology, University of Maryland. 1994 and 1996.
- Advised 3 MS thesis students and have participated as a graduate committee member for 1 MS and 3 PhD students.
Science and Products
The Challenge: Free-roaming cats (Felis catus) are nonnative predators of small mammals, songbirds and gamebirds, reptiles, amphibians, and insects. They are also competitors of native predators and vectors for diseases to human and wildlife. The US Fish and Wildlife Service is authorized to remove cats from National Wildlife Refuges. Presently cat trapping on Refuge lands is conducted opportunistically. Therefore a systematic monitoring and trapping scheme for estimating cat abundance and distribution needs to be tested. The scheme also needs to incorporate trapping methods that minimize non-target species interference to minimize the drain on Refuge resources.
The Challenge: Black-tailed prairie dogs are considered a keystone species for the prairie habitat. Many avian species are associated with black-tailed prairie dogs (Cynomys ludovicianus) in winter. Raptors feed on prairie dogs and non-raptor avian species forage within prairie dog colonies. However prairie dogs are also considered agricultural pests. The first generation anticoagulant rodenticide Rozol Prairie Dog Bait (chlorophacinone, active ingredient) is registered for control of prairie dogs during winter. Information is needed to determine if operational applications of Rozol at prairie dog colonies result in adverse effects to birds and other non-target wildlife.
The Challenge: Anticoagulant rodenticides have been identified as being hazardous to predatory and scavenging birds on a global scale. Restrictions on the sale, distribution and packaging of some second generation anticoagulant rodenticides (e.g., brodifacoum, difethialone, bromadiolone and difenacoum) have been instituted by the US EPA, and will likely result in expanded use of first-generation anticoagulant rodenticides (e.g., chlorophacinone, diphacinone). The risk posed by anticoagulant rodenticides to wildlife is inadequately characterized, and toxicological data are needed to better evaluate the threat of these compounds non-target organisms.
Rodenticide incidents of exposure and adverse effects on non-raptor birds
Interest in the adverse effects of rodenticides on birds has focused primarily on raptors. However, non-raptor birds are also poisoned (rodenticide exposure resulting in adverse effects including mortality) by rodenticides through consumption of the rodenticide bait and contaminated prey. A literature search for rodenticide incidents (evidence of...Vyas, Nimish B.
Influence of poisoned prey on foraging behavior of ferruginous hawks
We recorded 19 visits by ferruginous hawks (Buteo regalis) over 6 d at two black–tailed prairie dog (Cynomys ludovicianus) subcolonies poisoned with the rodenticide Rozol® Prairie Dog Bait (0.005% chlorophacinone active ingredient) and at an adjacent untreated subcolony. Before Rozol® application ferruginous hawks foraged in the untreated and...Vyas, Nimish B.; Kuncir, Frank; Clinton, Criss C.
The influence of study species selection on estimates of pesticide exposure in free-ranging birds
Field studies of pesticide effects on birds often utilize indicator species with the purpose 16 of extrapolating to other avian taxa. Little guidance exists for choosing indicator species to 17 monitor the presence and/or effects of contaminants that are labile in the environment or body, 18 but are acutely toxic, such as anticholinesterase (anti-...Borges, Shannon L.; Vyas, Nimish B.; Christman, Mary C.
Untested pesticide mitigation requirements: ecological, agricultural, and legal implications
Every pesticide sold in the United States must have a U.S. Environmental Agency approved label on its container. The label provides directions for the pesticide’s use and is legally enforceable under the Federal Insecticide, Fungicide and Rodenticide Act. For a pesticide with high ecological risks, mitigation statements may be included on the...Vyas, Nimish B.
Chlorophacinone residues in mammalian prey at a black-tailed prairie dog colony
Black-tailed prairie dogs (BTPDs), Cynomys ludovicianus, are an important prey for raptors; therefore, the use of the rodenticide Rozol (0.005% chlorophacinone active ingredient) to control BTPDs raises concern for secondary poisonings resulting from the consumption of contaminated prey by raptors. In the present study, the authors observed Rozol...Vyas, Nimish B.; Hulse, Craig S.; Rice, Clifford P.
Critique on the use of the standardized avian acute oral toxicity test for first generation anticoagulant rodenticides
Avian risk assessments for rodenticides are often driven by the results of standardized acute oral toxicity tests without regards to a toxicant's mode of action and time course of adverse effects. First generation anticoagulant rodenticides (FGARs) generally require multiple feedings over several days to achieve a threshold concentration in tissue...Vyas, Nimish B.; Rattner, Barnett A.
Acute oral toxicities of wildland fire control chemicals to birds
Wildland fire control chemicals are released into the environment by aerial and ground applications to manage rangeland, grassland, and forest fires. Acute oral 24 h median lethal dosages (LD50) for three fire retardants (Fire-Trol GTS-R?, Phos-Chek D-75F?, and Fire-Trol LCG-R?) and two Class A fire suppressant foams (Silv-Ex? and Phos-Chek WD881...Vyas, N.B.; Spann, J.W.; Hill, E.F.
Effects of Phos-Chek® G75-F and Silv-Ex® on red-winged blackbird (Agelaius phoeniceus) embryos
Effects of field application levels of wildfire control chemicals, Phos-Chek® G75-F (PC) and Silv-Ex® (SE), were examined on red-winged blackbird (Agelaius phoeniceus) embryos. Embryos were more sensitive to PC and SE when eggs were immersed for 10 s at an early developmental stage (days 3–5 of incubation) than at a later stage (days 6–9 of...Buscemi, D.M.; Hoffman, D.J.; Vyas, N.B.; Spann, J.W.; Kuenzel, W.J.
Dermal insecticide residues from birds inhabiting an orchard
The US Environmental Protection Agency conducts risk assessments of insecticide applications to wild birds using a model that is limited to the dietary route of exposure. However, free-flying birds are also exposed to insecticides via the inhalation and dermal routes. We measured azinphos-methyl residues on the skin plus feathers and the feet of...Vyas, N.B.; Spann, J.W.; Hulse, C.S.; Gentry, S.; Borges, S.L.
Field evaluation of an avian risk assessment model
We conducted two laboratory subacute dietary toxicity tests and one outdoor subacute dietary toxicity test to determine the effectiveness of the U.S. Environmental Protection Agency's deterministic risk assessment model for evaluating the potential of adverse effects to birds in the field. We tested technical-grade diazinon and its D Z N- 50W (50...Vyas, N.B.; Spann, J.W.; Hulse, C.S.; Borges, S.L.; Bennett, R.S.; Torrez, M.; Williams, B.I.; Leffel, R.
From the Field: Carbofuran detected on weathered raptor carcass feet
The cause of death for raptors poisoned at illegal carbofuran-Iaced predator baits is often not confirmed because the carcass matrices that are conventionally analyzed are not available due to decomposition and scavenging. However, many such carcasses retain intact feet that may have come into contact with carbofuran. Eastern screech owls (Otus...Vyas, N.B.; Spann, J.W.; Hulse, C.S.; Bauer, W.; Olson, S.
Decomposed gosling feet provide evidence of insecticide exposure
Canada goose goslings were exposed to turf sprayed with D.Z.N(R) diazinon 50W application (2.24 kg a.i./ha). The control plot was subjected to a water application. One foot from each bird was placed outdoors for 7 d to decompose and the other foot was kept frozen. Diazinon residues were analyzed on both feet. Results showed that diazinon was...Vyas, N.B.; Spann, J.W.; Hulse, C.S.; Torrez, M.; Williams, B.I.; Leffel, R.