Ž .
Fig. 5. The frequency of aggressive pecks over a 2-day period nine 20-min observations per day in small Ž
. sample groups from mixed flocks. The values shown are the mean number SEM of aggressive pecks per
Ž .
20 min for four groups of birds picked out roosting closely together ‘‘close’’ and four groups of birds picked Ž
. out roosting far apart from each other ‘‘apart’’ . The values from day 1 are used in a repeated measure
ANOVA. The test showed a significant difference between the ‘‘close’’ and the ‘‘apart’’ groups from mixed Ž
. flocks F s6.13, df s1 and 6, P - 0.05 .
min-periods day 1 in the experiment were used to test the difference between the Ž
. treatments ‘‘close’’ and ‘‘apart’’, using eight groups per treatment Altman, 1994 . The
results are shown in Figs. 4 and 5. Statistics in both experiments were performed using Ž
. Statview for Macintosh, Version 1.0 .
3. Results
3.1. Space use and constancy of night roosting site As shown in Table 1, groups from the ends of the pens used the same roosting site
Ž .
tier and section at night significantly more than random. Many end groups also stayed significantly more within the sections that they were marked in during the daytime.
However, groups from the middle of the pens generally did not. The pattern was about the same regardless of the sex composition in the pens: in seven of the pens nearly all
end group birds used the same roosting site during the 2 consecutive nights. In seven of the eight pens, birds from either one or both end groups stayed significantly more often
during daytime in the section they were marked at night than could be expected by chance.
Ž .
We also compared roosting both nights in the same roosting site with roosting in the Ž
. adjacent section and most distant section Fig. 2 . Regardless of sex composition in the
Ž flocks, most birds from end-groups used the same roosting sites both nights single-sexed,
. P - 0.001, mixed P - 0.001 , whereas birds from the middle of the pens generally were
much less consistent in their choice of roosting site. A similar analysis of the daytime locations showed that the sections of the night roost were used significantly more than
Ž other sections during the daytime by end group birds single-sexed, P - 0.05, mixed,
. Ž
. P - 0.05 ; but again for mid-pen groups, this was not the case Fig. 3 .
3.2. Aggression in small sample groups The results show that during the observations the first day, there were significantly
Ž less aggressive pecks in ‘‘close’’ groups than in ‘‘apart’’ groups from mixed flocks Fig.
. 5, P - 0.05 . But in groups from single-sexed flocks, there was no significant difference
Ž .
Ž .
Fig 4, P s 0.43 . When the data was pooled ss q m , there was a tendency for higher Ž
values in groups of birds that had been roosting far apart from each other F s 4.42, .
df s 1 and 14, P s 0.05 . There were no significant differences between groups during the second day.
There were no significant differences between the treatments in the numbers of threats, avoidances, gentle and severe feather pecks in all small sample groups from
mixed flocks as compared to groups from single-sexed flocks. In the sample investigated in this report, there were more performers of aggressive
Ž pecks in day 1 as compared to day 2 mean number in ‘‘close’’ groups: 2 compared to
. 1.5, and in ‘‘apart’’ groups 2.5 to 1.5 . The mean number of performers in ‘‘apart’’
groups from mixed flocks were 2 compared to 1, whereas in ‘‘apart’’ groups from single-sexed flocks, the means were 3 compared to 2. Retaliations of the dominance
order were evenly spread between the groups and over the days. No hypothesis testing was performed because of the small number of registrations.
4. Discussion
