Beacon No. 1 2004 - Skuld

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LOSS PREVENTION Counting the dead By Dr. Ted Tomasi, ENTRIX, Inc. We’ve heard often enough of the difficulty of placing a value on human life. Does it get any easier with bird life? The impact of an oil spill on local bird populations can be devastating. How do we count the dead? This is a critical question when costs per mortality range from a few hundred to tens of thousands of US dollars. Effects of oil spills on bird populations are often a major cost associated with an oil spill. Depending on time of year and location, even small spills can have significant effects. Images of oiled birds trigger emotional public responses – and if rare or endangered species are involved, the stakes are that much higher. Costs associated with compensatory Photo: Courtesy of the U.S.Coast Guard restoration actions range from a few hundred dollars per bird to USD 30- 60,000 dollars per bird if endangered species are impacted. How does one estimate total bird mortality following a spill? Typically, the carcasses found after a spill represent a fraction of the total mortality, and estimation of mortality requires modeling. The accuracy of the estimate depends critically on how responders organize to collect bird data. In our experience, unless someone familiar with the model directs a targeted and coordinated effort, mortality estimates tend to be inaccurate, and usually too high. One modeling approach is called the ‘Beached Bird Model’. The number of carcasses collected on shorelines is less than the true mortality since birds can sink before they reach the shore, birds can be removed by scavengers before searches, and birds on the shore can be overlooked by searchers and not found. The combination of these effects is estimated in the beached bird model, and leads to a multiplier for collected carcasses. For example, if 75% of the birds sink, are scavenged or are overlooked, then the multiplier is four and 100 dead ducks on the shore is 400 dead ducks in total. Sinking Data from open, rough water indicate that almost all birds float for at least three days after they die, and that about 90% of birds float for two weeks. After that, the rate of sinking increases dramatically. Birds dying near-shore will probably float to land, depending on local winds and currents. Knowing the influence of these factors is crucial. If birds are transported offshore, or if birds die offshore, sinking will be a factor. Hydrodynamic models can be used to simulate the fate of birds; if the trajectory is such that landfall doesn’t occur within two weeks, sinking will increase multipliers. In our experience, having good aerial observations of where oil is moving relative to bird densities may significantly reduce uncertainties about the sinking factor. Bird carcasses found after a spill are only a fraction of the total mortality 14 BEACON
Photo: Courtesy of the U.S.Coast Guard Spill responders shouldn’t replace dedicated, trained bird searchers Scavenging Dead birds may be removed from the shoreline by scavengers before searchers arrive. Small carcasses (under 500 grams) can be scavenged by mammals and birds, such as ravens, and removed from shorelines quickly (perhaps 66% on the first day). Large carcasses cannot be removed by birds or small mammals; scavenging of large carcasses tends to occur at night, at rates of less than 8% per day. The longer the period between searches at a location, the more likely it is that a bird will be removed by a scavenger before the next search. Greater search frequency means a smaller multiplier. It is vital to have systematic, frequent bird searches, and to document all search effort, even informal effort, such as that by the public, SCAT teams, or clean-up crews. All spill responders should be told to look for bird carcasses, to search oiled wrack before its disposal, and to document observations. But as this is not responders’ primary function, they should not substitute for trained, dedicated bird searchers, distinct from wildlife rehabilitators, who tend to focus on live birds. Background deposition Carcasses unrelated to the spill need to be netted out of mortality estimates. Five to ten percent of the carcasses are due to ‘background deposition’. The condition of each bird collected should be photodocumented. For high multiplier birds, it is appropriate to fingerprint oiled feathers and have them necropsied. Implications During spill response, bird data collection is often inadequate or poorly documented. This leads to insufficient or underestimated search effort, increased uncertainties about sinking, the inclusion of carcasses not related to the spill, and higher mortality estimates. These pitfalls, and the USD 30,000 to USD 60,000 costs that can be associated with the assumed death of a single endangered bird, can be avoided. In the United States and areas affected by the Oil Pollution Act, knowledge of these factors and rapid response efforts can help avoid overly conservative estimates of bird mortality. For more information, please contact Dr. Ted Tomasi at ttomasi@entrix.com. Searcher efficiency <strong>No</strong>t all birds on a shoreline are found during a search. Birds in the wrack line, small birds hidden in the rocks, and even birds on open sand can be hard to find. Bird size and coloration, as well as shoreline substrate will affect search efficiency. Experiments suggest that small carcasses (less than 300 grams) are found about 60% of the time, while carcasses over 1,000 grams are found over 80% of the time. More highly trained and experienced searchers are more efficient, serving to lower multipliers. Photo: Courtesy of the U.S.Coast Guard DURING SPILL RESPONSE, BIRD DATA COLLECTION IS OFTEN INADEQUATE OR POORLY DOCUMENTED. THIS LEADS TO INSUFFICIENT OR UNDERESTIMATED SEARCH EFFORT, INCREASED UNCERTAINTIES ABOUT SINKING, THE INCLUSION OF CARCASSES NOT RELATED TO THE SPILL, AND HIGHER MORTALITY ESTIMATES Experiments show that birds over 1,000 grams are found 80% of the time. The smaller the bird, the more likelihood of it remaining unfound BEACON 15
Page 1 and 2: Chicken Run - killer viruses, now a
Page 3 and 4: CONTENTS PAGE 6 PAGE 10 PAGE 16 PAG
Page 5 and 6: a growing market She is familiar wi
Page 7 and 8: Marine bulk carrier and tanker vess
Page 9 and 10: LOSS PREVENTION Photo: Scanpix Cond
Page 11 and 12: iruses, now and forever First there
Page 13: Bird flu has jumped the species bar
Page 17 and 18: Photo: Scanpix A stowaway from the
Page 19 and 20: The U.S. Coast Guard prepare to sea
Page 21 and 22: Around 60% of Smit Salvage’s work
Page 23 and 24: Don’t let the ISPS Code put your
Page 25 and 26: Suit For the purposes of English la
Page 27 and 28: LEGAL NOTES Ronny Larsen, Claims Ex
Page 29 and 30: Photo: Scanpix U.S. Courts adopt a
Page 31 and 32: Contact Skuld HONG KONG Christian R

Beacon No. 1 2004 - Skuld

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