Rat Poison has killed other Red-tailed Hawks -- and an important PS

The new nest under construction in Riverside Park - May 21, 2008
Courtesy of PaleMale.com
[Note that this young pair of redtails have constructed the 2nd nest in the crotch of a London Plane, not on the edge of a branch as they did in nest#1. Quick learners.

It has become clear the the Riverside Park chicks were poisoned by an anticoagulant of the type commonly used in rodenticides. A website correspondent from Michigan, Debbie Olsen, alerted me to the following article:

Anticoagulant Rodenticide Exposure in Birds of Prey in Massachusetts

Anticoagulant rodenticides are used to control rodent populations in various settings, including urban, suburban, and agricultural areas. These rodenticides disrupt blood clotting pathways, resulting in excessive bleeding and death. While effective in controlling rodent overpopulation, these poisons can also cause mortality in non-target species of mammals and birds that ingest the bait (primary exposure) or ingest poisoned animals (secondary exposure).

Brodifacoum is a second-generation anticoagulant rodenticide that is currently available for household use in a variety of forms, including bait blocks and pellets. This compound presents a high risk for unintended poisoning of wildlife due its long persistence time in liver tissue. Brodifacoum is the rodenticide that has been identified in birds of prey suffering from anticoagulant rodenticide toxicosis that have been treated at Tufts Wildlife Clinic (TWC).

The most frequent species treated at TWC for anticoagulant rodenticide toxicosis is the red-tailed hawk (Buteo jamaicensis), which predominantly feeds on small- to medium-sized mammals but will also consume birds. Affected hawks present extremely anemic and weak with evidence of profuse bleeding from minor lacerations or extensive bruising with no evidence of serious traumatic injuries such as fractures. If these birds are not found and treated they will die due to blood loss. However, if they are found in time and receive aggressive medical treatment for blood loss and the antidote for the rodenticide (Vitamin K 1), they can recover and be released back to the wild.

The clinical cases treated at TWC, together with reports on widespread anticoagulant rodenticide exposure in birds of prey in New York state, led to this ongoing project intended to survey the extent of exposure of birds of prey in urban and suburban areas of Massachusetts to these compounds. Species included in this study are red-tailed hawks, barred owls (Strix varia), eastern screech owls (Otus asio), and great horned owls (Bubo virginianus).

Documenting the presence of these rodenticides in predators such as birds of prey reflects the far-reaching effects of human activity on environmental health. As rodent populations flourish in human-altered landscapes, attempts to control these populations have potential consequences for animals higher in the food chain. This project, therefore, demonstrates a fundamental concept of conservation medicine: the interconnectedness of humans, animals, and ecosystems.

Principal Investigator: Maureen Murray, D.V.M.

Co-Investigator: Florina Tseng, D.V.M.

Project Funder: Animal Welfare Institute

References:

Murray M. and Tseng F. In Press. Diagnosis and Treatment of Secondary Anticoagulant Rodenticide Toxicosis in a Red-tailed Hawk ( Buteo jamaicensis ). Journal of Avian Medicine and Surgery.

Stone,W.B., J.C. Okoniewski, and J.R. Stedelin. 2003. Anticoagulant rodenticides and raptors: recent findings from New York, 1998-2001. Bull Environ Contam Toxicol. 70:34-40.

The item comes from the Tufts University - Cummings School of Veterinary Medicine -- URL: http://www.tufts.edu/vet/wildlife/rodenticide.html


PS I spoke at some length yesterday with Glenn Phillips, the executive Director of NYC Audubon.

Egg retrieval
We discussed plans for egg retrieval at the Fifth Avenue nest Soon! Perhaps next week. Why the delay? The building is sending up a window-washer platform next week for facade work. The workers will remove the eggs. This will save NYCA the $15,000 cost of hiring its own removal crew. And, according to Phillips, it may not be too late for the diploidy test, the one that could reveal whether the eggs in the nest were fertilized].

MBPM-2
We discussed the Memorandum interpreting the Migratory Bird Treaty Act. MBPM-2 -- issued by the US Fish & Wildlife Service in April 2003. This was the Memo that facilitated the removal of Pale Male's nest in 2004. I have been strongly in favor of a fight to remove this Memorandum from the books. Phillips explained NYCA's complicated stand on this issue -- and why they believe working for the removal of MBPM-2 might not be the way to go. He was quite convincing. [More on this at a later date].

Rat Poisons
We also discussed the rat-poisoning issue . I understand that neither Central Park nor Riverside Park use the anticoagulant-type of rodenticide. Therefore it is likely that the stuff involved in the Riverside Park poisonings was put out by some nearby building to control rats in their basement or around their garbage areas.
Consequently NYCA is planning an education campaign for all buildings on the periphery of Central Park and Riverside Park, to inform building managements of the dangers to local wildlife of using toxic rodenticides.

NB: Concessions within Central Park [Tavern on the Green, the Boathouse] and Riverside Park [various Cafes] do not observe the same rules as the parks do. We have to find out just who sets the rat-baiting rules for them -- it remains unclear. That they use powerful rodenticides is certain.