Behavior of ISA Brown hens was compared in cages with and without nest sites provided, to determine the characteristics necessary for such nest sites and whether part of the existing cage area could be modified to form an acceptable nest file. 2. There were 5 treatments: control (C); a wooden surround in one rear corner of the cage (S); a fiberglass rollaway hollow in one rear corner of the cage (H); a hollow and a surround (H/S); a nest box attached to the back of the cage, containing a hollow (N). 3. Use of rollaway hollows was limited, unless they were blocked and wood shavings were added, when 55 to 60% of eggs were laid in them. There were also problems with soiling of hollows. 4. When hollows were blocked, most hens used them in treatments H/S and N, suggesting that substrate and surroundings both contributed to acceptability of nest sites. 5. Pre-laying behaviour in sites within the cage was disturbed and sometimes abnormal. In addition, these sites were not used for other activities, thus limiting the space available. 6. For pre-laying behaviour to be expressed satisfactorily in cages, an additional nesting area, such as a nest box or boxes, is probably necessary.
