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.

Effects of age and disturbance on fear in pheasants kept in a rearing facility

“…According to previous studies, the duration of TI increases with an increasing age of birds (Borchelt and Ratner 1973;Benoff and Siegel 1976;Brake et al 1994;Vestergaard and Sanotra 1999;Nowaczewski et al 2012). In our study, the effect of age was seen only in group D, but in the opposite way; with increasing age, the duration of TI decreased.…”

“…Therefore, we did not take sex into account in our research, however, the sex ratio of the tested pheasants in both groups was almost equal. In previous studies, the effect of animal weight on the duration of TI was not found (Nowaczewski et al 2012). In our study, the differences in the weight of the tested pheasants were mainly related to their growth during the monitored period, thus we assessed this as the effect of age on the TI response, not the effect of the weight of individual birds.…”

“…The probable explanation is the different age range observed in our and other studies. Nowaczewski et al (2012) tested TI in pheasants on days 10, 20, and 35 of their lives. 1.07 ± 0.07 a,x 1.00 ± 0.00 a,x 358.0 ± 47.0 a,x 474.5 ± 49.0 ab,x 10 weeks 1.20 ± 0.02 a,x 1.00 ± 0.00 a,x 327.3 ± 51.6 a,y 554.7 ± 25.3 a,x 12 weeks 1.08 ± 0.07 a,x 1.08 ± 0.08 a,x 350.8 ± 52.8 a,x 470.2 ± 52.0 ab,x 14 weeks 1.07 ± 0.07 a,x 1.00 ± 0.00 a,x 429.3 ± 38.3 a,x 402.9 ± 50.8 b,x 16 weeks 1.00 ± 0.00 a,x 1.40 ± 0.27 a,x 314.9 ± 44.7 a,x 403.6 ± 60.2 b,x a,b Means within the same column lacking a common letter of superscript (a, b) differ significantly (P < 0.05).…”

“…In our study, pheasants aged 8 to 16 weeks (56 to 112 days) were observed, thus they were older birds than those tested in previous studies. For comparisons, the results published by Nowaczewski et al (2012) are particularly interesting since they tested captive-reared pheasants (while the other studies evaluated changes in the TI duration in domestic poultry). Based on their results, Nowaczewski et al (2012) assumed that in the period from day 10 to 35 day of life, the pheasants became less resistant to stress, resulting in extended TI duration (from 62.6 s to 127.3 s).…”

“…For comparisons, the results published by Nowaczewski et al (2012) are particularly interesting since they tested captive-reared pheasants (while the other studies evaluated changes in the TI duration in domestic poultry). Based on their results, Nowaczewski et al (2012) assumed that in the period from day 10 to 35 day of life, the pheasants became less resistant to stress, resulting in extended TI duration (from 62.6 s to 127.3 s). In terms of practical implications, Nowaczewski et al (2012) concluded that while these older birds would be more susceptible to stress on farms, they may have a better defence mechanism when potentially endangered by a predator in the wild.…”