Lead exposure in scavenging corvids
1 Formal:
In Scandinavia, more than 90% of the hunted big game is shot with lead-based bullets. Shot animals are commonly field dressed and the remains are left at the spot. Lead fragments from the bullets are a threat for scavenging animals. Corvids are consuming a major part of these hunting remains. This study aims to measure recent and long-term exposure of corvids to lead and other heavy metals. Short-term exposure is measured in the blood and values before the moose hunt can be compared to values during the moose hunt.
2: Skadevirkninger:
Two groups of birds are used for the study: Corvids trapped in crow traps immediately before and during the big game hunting season and killed by hunters (Group 1). Blood from these birds will be sampled by trained research personnel prior to euthanasia and brain, liver and femoral bone samples will be collected euthanasia. The second group are birds captured in crow traps before the moose hunting season. The birds will be blood sampled, marked and released. We aim to obtain paired samples and will recapture marked birds using crow traps or drop-nets or if needed, shot gun and rifles. Recaptured birds are blood sampled and brain, liver and femoral bone samples will be collected from killed animals.
Forventet nytteverdi:
In Scandinavia one similar study has shown higher blood lead levels in adult golden eagles sampled during the moose hunting season compared to juvenile golden eagles sampled prior to the hunting season. The current study focuses on the main consumer of hunting remains, it aims to overcome the age dependent results (adult birds might have accumulated more lead) and to document hunting-lead exposure from spent ammunition within individual birds. We hypothesize a hunting season dependent increase of blood lead levels and a general high long long-term exposure. If so, the study will support policy makers for hunting regulations and individual hunters in selection of non-lead ammunition.
Antal dyr og art
Within group 1, we aim to sample 100 birds from each of the following species: Common raven (Ravn) Corvus corax; hooded crow (Kråke) Corvus corone cornix; Eurasian jay (Nøtteskrike) Garralus glandarius; and Eurasian magpie (Skjære) Pica pica. In group 2, we will use a maximum of 200 hooded crows and common ravens.
Hvordan etterleve 3R
By using hunter killed birds for group 1 we are using a resource already available. Group 1 will provide a large sample and we depend on experienced hunters to trap ravens. The paired samples from group 2 will increase the relevance of the study. For individual marking, we are will use common bird rings provided by the Ringmerkingssentralen (Stavanger Museum) and for distant identification, we will use hydrogen peroxide to bleach one to two feathers that will molt out. All killing of these birds are will be within the legal species-specific hunting season.
In Scandinavia, more than 90% of the hunted big game is shot with lead-based bullets. Shot animals are commonly field dressed and the remains are left at the spot. Lead fragments from the bullets are a threat for scavenging animals. Corvids are consuming a major part of these hunting remains. This study aims to measure recent and long-term exposure of corvids to lead and other heavy metals. Short-term exposure is measured in the blood and values before the moose hunt can be compared to values during the moose hunt.
2: Skadevirkninger:
Two groups of birds are used for the study: Corvids trapped in crow traps immediately before and during the big game hunting season and killed by hunters (Group 1). Blood from these birds will be sampled by trained research personnel prior to euthanasia and brain, liver and femoral bone samples will be collected euthanasia. The second group are birds captured in crow traps before the moose hunting season. The birds will be blood sampled, marked and released. We aim to obtain paired samples and will recapture marked birds using crow traps or drop-nets or if needed, shot gun and rifles. Recaptured birds are blood sampled and brain, liver and femoral bone samples will be collected from killed animals.
Forventet nytteverdi:
In Scandinavia one similar study has shown higher blood lead levels in adult golden eagles sampled during the moose hunting season compared to juvenile golden eagles sampled prior to the hunting season. The current study focuses on the main consumer of hunting remains, it aims to overcome the age dependent results (adult birds might have accumulated more lead) and to document hunting-lead exposure from spent ammunition within individual birds. We hypothesize a hunting season dependent increase of blood lead levels and a general high long long-term exposure. If so, the study will support policy makers for hunting regulations and individual hunters in selection of non-lead ammunition.
Antal dyr og art
Within group 1, we aim to sample 100 birds from each of the following species: Common raven (Ravn) Corvus corax; hooded crow (Kråke) Corvus corone cornix; Eurasian jay (Nøtteskrike) Garralus glandarius; and Eurasian magpie (Skjære) Pica pica. In group 2, we will use a maximum of 200 hooded crows and common ravens.
Hvordan etterleve 3R
By using hunter killed birds for group 1 we are using a resource already available. Group 1 will provide a large sample and we depend on experienced hunters to trap ravens. The paired samples from group 2 will increase the relevance of the study. For individual marking, we are will use common bird rings provided by the Ringmerkingssentralen (Stavanger Museum) and for distant identification, we will use hydrogen peroxide to bleach one to two feathers that will molt out. All killing of these birds are will be within the legal species-specific hunting season.