Action: Remove ectoparasites from feathers to increase survival or reproductive success
- A replicated and controlled study in the UK found that red grouse Lagopus lagopus scoticus treated with spot applications had lower tick and disease burdens and higher survival than controls, whilst birds with impregnated tags had lower tick burdens only.
- A replicated ex situ study in Hawaii found that CO2 was the most effective way to remove lice from feathers, although this treatment did not kill the lice.
Ectoparasites have the greatest impacts on young birds, but can also reduce the fitness or condition of adults. In addition, they can be important carriers of diseases, such as ticks carrying louping ill virus LIV.
Supporting evidence from individual studies
A replicated and controlled study in 1995-6 on a grouse moor in Morayshire, Scotland (Laurenson et al. 1997), found that red grouse Lagopus lagopus scoticus treated with spot applications of deltamethrin had significantly lower tick burdens, compared to control birds, significantly lower louping ill virus (LIV) infections and higher survival rates at ten weeks old compared with controls (82% survival for seven treated broods vs. 64% for seven controls). Chicks treated with lambdacyhalothrin-impregnated (tick-removal) tags also had lower tick burdens than controls, as did chicks from broods where mother only was treated (0-0.1 immature ticks/chick for broods with treated chicks vs. 0.5-0.7 for broods with treated hens and 1.4-2.3 for controls), but they did not have lower LIV infection rates or increased survival to ten weeks old.
A replicated ex situ study in Hawaii (Visnak & Dumbacher 1999) tested four different fumigants (chloroform, di-ethyl ether, ethyl acetate and carbon dioxide, CO2) to assess the efficiency and speed with which they immobilised and detached slender pigeon lice Columbicola columbae from the feathers of feral pigeons Columba livia. CO2 was fastest in immobilising lice (average of 61 s for three trials of ten lice), followed by chloroform (122 s), ethyl acetate (198 s) and ether (201 s). CO2 was also fastest at detaching lice from feathers (average of 181 s for 30 lice) followed by chloroform (192 s), ethyl acetate (293 s) and ether (307 s). However, CO2 only detached 22% of lice, compared to 33% for ethyl acetate, 56% for ether and 76% for chloroform. In addition, CO2 (unlike the other chemicals) did not kill the lice, which quickly recovered when given fresh air.
- Laurenson M.K., Hudson P.J., McGuire K. & Thirgood S.J. (1997) Efficacy of acaricidal tags and pour-on as prophylaxis against ticks and louping-ill in red grouse. Medical and Veterinary Entomology, 11, 389-393
- Visnak R.M. & Dumbacher J.P. (1999) Comparison of Four Fumigants for Removing Avian Lice (Comparación de Cuatro Fumigantes para Remover Mallofaga en Aves). Journal of Field Ornithology, 70, 42-48