Chemical communication in wild Norway rats: (Rattus norvegicus Berkenhout)

Landete-Castillejos, Tomás (1997) Chemical communication in wild Norway rats: (Rattus norvegicus Berkenhout). PhD thesis, University of Nottingham.

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Abstract

This study examined the urine and faecal scent marking behaviour and investigatory responses of wild Norway rats (Rattus norvegicus Berkenhout) kept in large, semi-natural enclosures to assess the role these scents play in their communication system.

For the first time, this study has shown that Norway rats deposit faecal scent marks in response to odour cues and form latrines. The spatial distribution of faeces was highly uneven. Most faeces deposited in open areas were found in clusters occupying less than 1 m2 which were termed latrines. Rats spent more time at feeders and in other areas which were almost devoid of faeces than at these latrines. This suggests that latrines were created deliberately, perhaps for communication.

Rats discriminated among faeces from different donors with respect to their investigation, presumably using olfactory cues. They faecal marked in response to urine cues from rats belonging to other colonies, although they did not faecal mark in response to their own urine cues or to a novel non-social stimulus (clean tiles). Investigation and faecal marking was aimed mainly towards urine from individuals of the marker's own sex. This suggests that faecal marking may play a role in communication between competitors.

Urine was deposited as discrete marks around the enclosures, in an uneven distribution. The highest density of marks was found by the enclosure walls and nest areas. Rats showed a greater urine marking response towards introduced clean surfaces than towards surfaces they had already marked, ensuring that their home area was always covered with their urine marks. Close monitoring of urine marking on clean surfaces showed that male -rats had a marking rate three times greater than that of females. This could not be attributed solely to weight differences between males and females.

Rats also urine marked in response to urine deposited by rats from other colonies. Urine from unfamiliar rats of the subject's own sex stimulated more investigation than urine from the opposite sex, though donors were immature. These results suggest that urine marking also plays a role in communication between competitors.

Testing individuals in their home enclosure, using scent marks deposited naturally by rats, and the contexts in which scent stimuli are deposited by donors (e. g. as part of their home range) and found by residents (e. g. finding intruder's home range marks in the resident's home range) were essential factors in determining their response to olfactory cues. The importance of these factors is discussed.

Item Type:Thesis (PhD)
Supervisors:Hurst, Jane
Uncontrolled Keywords:rats, Rattus norvegicus, animal scent, scent markings, animal communication
Faculties/Schools:UK Campuses > Faculty of Science > School of Biosciences
ID Code:1231
Deposited By:Ms. K EVANS
Deposited On:19 Apr 2010 15:42
Last Modified:19 Apr 2010 15:42

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