Parasitic infection kills buzzards on the Broekpolder

In mid-March two buzzards from the Broekpolder were delivered to the bird sanctuary in Delft with signs of regurgitation; one died shortly after and the other, which developed seizures,  was euthanized; both were submitted to the DWHC for post-mortem exam. Although poisoning was suspected based on the clinical signs, our investigations showed that both appeared to have died from a parasitic infection. Associated lesions were found on the tongue, gizzard and intestines of the male bird, and only on the tongue of the female. These findings make it highly unlikely that poison played a role in the deaths. No signs consistent with intoxication with well-known poisonous substances such as Aldicarb or rat poison, which typically lead to a rapid death, were observed in these birds.

The female bird had not eaten for several days and is thought to have died from a severe bleed in the stomach. This phenomenon is recognised in songbirds in which, after 12-24 hours without food bleeds can occur throughout the gastrointestinal tract. It is unknown as to why this buzzard stopped eating and how long a bird of prey can survive without food before gastrointestinal bleeding occurs or, indeed, if this was the cause of the bleed in the stomach of the buzzard. Both buzzards were well-muscled and the male had sufficient fat reserves whilst the female had only few fat reserves.

Parasites are common in avian species and are not typically associated with disease. However, in some cases, their presence in certain tissues can lead to inflammation as previously described in buzzards, kestrels and marsh harriers. Environmental factors and/or stress which challenge the host birds health can lead to the parasitic infection becoming clinically significant. It is not clear what led to the development of lesions associated with the parasitic infections in these cases. Inflammation of the tongue may have led to regurgitation, explaining the empty stomach and poor fat reserves in the female bird. It is possible that the seizures were secondary to the blood loss into the stomach.