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2013 Depredation Investigations

Domestic animals can die for a variety of reasons—due to predators (wolf, cougar, coyote or bear), weather, disease or injury. When a livestock producer believes wolves are involved in the loss or injury of their livestock, ODFW carefully investigates to determine if wolves were involved.

First, ODFW closely examines evidence (the domestic animal’s carcass, signs of struggle) to determine if the domestic animal was actually killed or injured by a predator—and not just scavenged by one after dying from another cause.

If the death or injury is determined to be predator-caused, further examination of the carcass and other evidence is needed to determine if wolves (rather than cougars, bears, coyotes) were responsible. Radio-collar data, any eyewitness accounts and wolf sign such as tracks or scat can help indicate if wolves were in the area at the time.

ODFW uses the same criteria as USDA Wildlife Services to classify the findings of wolf-livestock loss investigations. In some cases, livestock losses cannot be confirmed to be caused by wolves because there is not enough evidence. In others, an investigation finds the domestic animal died by an entirely different cause. More detail on the classifications used is below.

For information on how ODFW responds to a confirmed livestock loss to a wolf, see Chapter 3 of the Wolf Conservation and Management Plan and Oregon Administrative Rule 635-110.

Note: Investigations listed below which have a finding of “Confirmed” are not necessarily "Qualified" toward lethal control options pursuant to OAR 635-110-0010(8)(a-c).

Depredation Investigation Reports (pdfs)

2022 | 2021 | 2020 | 2019 | 2018 | 2017 | 2016 | 2015 | 2014 | 2013 | 2012 | 2011


In June 2013, ODFW changed the format of the investigation summaries to depredation investigation reports. These reports will contain more detail.












Reported wolf incidents should be classified as either confirmed, probable, possible/unknown, or other, based on the following criteria.

CONFIRMED – Depredation is confirmed in those cases where there is reasonable physical evidence that an animal was actually attacked and/or killed by a predator. The primary confirmation factor would ordinarily be the presence of bite marks and associated subcutaneous hemorrhaging and tissue damage, indicating that the attack occurred while the victim was alive, as opposed to simply feeding on an already dead animal. Spacing between canine tooth punctures, feeding pattern on the carcass, fresh tracks, scat, hairs rubbed off on fences or brush, and/or eye witness accounts of the attack may help identify the specific species or individual responsible for the depredation. Predation might also be confirmed in the absence of bite marks and associated hemorrhaging (i.e., if much of the carcass has already been consumed by the predator or scavengers) if there is other physical evidence to confirm predation on the live animal. This might include blood spilled or sprayed at a nearby attack site or other evidence of an attack or struggle. There may also be nearby remains of other victims for which there is still sufficient evidence to confirm predation, allowing reasonable inference of confirmed predation on the animal that has been largely consumed.

PROBABLE – Having some evidence to suggest possible predation, but lacking sufficient evidence to clearly confirm predation by a particular species, a kill may be classified as probable depending on a number of other factors such as: (1) Has there been any recently confirmed predation by the suspected depredating species in the same or nearby area? (2) How recently had the livestock owner or his employees observed the livestock? (3) Is there evidence (telemetry monitoring data, sightings, howling, fresh tracks, etc.) to suggest that the suspected depredating species may have been in the area when the depredation occurred? All of these factors, and possibly others, should be considered in the investigator’s best professional judgment.

POSSIBLE/UNKNOWN – Lacking sufficient evidence to classify an incident as either confirmed or probable predation, the possible/unknown classification is appropriate if it is unclear what the cause of death may have been. The investigator may or may not have much of a carcass remaining for inspection, or the carcass may have deteriorated so as to be of no use. The investigator would want to consider if the area has been frequented by a predator, or if the habitat is one which the predator is likely to use. Possible predation may include cases where counts show that abnormal numbers of livestock are missing or have disappeared above and beyond past experience, and where other known cases of predation have occurred previously in the area.

OTHER – Cause of livestock deaths should be classified as other when it is discovered that the cause of death was not likely caused by the animal originally reported to Wildlife Services during a request for assistance. Examples of other may include cases where the cause of death is confirmed or is likely due to predation by some other animal or cause determined at the time of the investigation such as red fox instead of coyote or other causes such as, bloat, poisonous plants, stillborn, disease, lightning strike, vehicle collision, etc.

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