Characteristics of the tonic immobility reaction in young farm-reared ring-neck pheasants, common quails and grey partridges

Abstract

Many species of game birds would become extinct in their natural habitat without periodical supplementation of wildlife populations with specimens bred on farms. Unfortunately either such birds do not exhibit any specific forms of behaviour which enable survival in natural environment or those forms are inappropriately developed. They include duration of tonic immobility (TI), which is often an anti-predator reaction. Pheasants, quails and partridges were subjected to assessment of the duration of TI and the number of inductions necessary to obtain TI on the 10th, 20th and 35th day of the birds’ lives. In the pheasant and quail, both the frequency of inductions equal to 1 and the duration of TI increased with age. The quails were characterised by the shortest duration of TI and the highest frequency of number of inductions above 1. In the partridges, the average frequency of TI inductions equal to 1 was the highest (more than 70% in every analyzed day). Simultaneously, the average duration of TI was long. This may indicate that these birds may have a better defence mechanism when endangered by a predator.