Scent Marking (Pasting) in a Colony of Immature Spotted Hyenas (Crocuta crocuta): A Developmental Study

1. What they did

Spotted hyenas mark their home ranges by defecating at latrines, scratching the ground (which leaves scent from glands between the toes) and pasting. When pasting, a hyena walks forward over a grass stalk or other object with the tail raised and hindquarters lowered, leaving a smear of anal gland secretion with a strong soapy smell. Both sexes paste in the same way.

The authors watched pasting in two groups (cohorts) of young captive hyenas, 20 in all, as they grew towards puberty. The hyenas were collected as infants in Narok District, Kenya, and raised in peer groups without their mothers, so that the strong influence of a mother’s rank would not hide any differences between the sexes. Six of them (four females and two males) had their ovaries or testes removed at 4 to 6 months of age, as a first test of whether sex hormones drive pasting.

They asked:

• Does pasting increase as hyenas approach puberty?
• Do females and males paste at different rates?
• Does pasting depend on hormones from the ovaries or testes?
• Do dominant hyenas paste more?
• Does one hyena’s pasting set off pasting by others, as had been seen in the wild?
• What do hyenas do just before they paste?

Observers recorded every pasting, plus aggression, submission, play, meeting ceremonies and sniffing, on a voice-activated tape recorder between 6 and 10 in the evening. Hyenas were recognized by patterns dyed on their fur. Observation time ranged from 18.7 to 64.9 hours per cohort and age period. Dominance ranks came from a competitive feeding test. Ages were split into juvenile (7 to 10 months, second cohort only), early subadult (12 to 18 months) and late subadult (19 to 22 months).

2. What they found

Pasting rose with age

• Nineteen of the 20 hyenas pasted more often in the late subadult period than in the early subadult period.
• The average rate rose from 0.080 to 0.767 pastings per hour in the first cohort, and from 0.121 to 0.531 in the second. In the second cohort it also rose from the juvenile period (0.052 per hour).

No difference between the sexes, and no effect of gonadectomy

• Females and males pasted at similar rates.
• Hyenas without ovaries or testes pasted as often as intact ones.

Dominance

• Higher-ranking hyenas tended to paste more. The link was significant in the late subadult period and borderline in the early subadult period.

Pasting is contagious

• In the late subadult period, a pasting by one hyena was quickly followed by pasting from others, mostly within the first minute, then fell back to the usual rate.
• In that first minute, pasting was more than 20 times as frequent as the usual rate.
• Most pastings happened in bouts (several animals pasting within 2 minutes of each other): 89% in the first cohort and 74% in the second.

What came before pasting

• Sniffing other hyenas (or being sniffed), sniffing fresh paste marks, and pasting itself made up about 72% of the behaviours just before a pasting, in both cohorts. Each came before pasting more often than expected by chance.
• Play, aggression or submission, and sniffing the ground, latrine or unmarked objects came before pasting less often than expected, even though play and aggression were common.
• Meeting ceremonies came before pasting about as often as expected by chance.

3. What they concluded

• Pasting increases as hyenas approach puberty, with no difference between females and males, which agrees with field observations of young wild hyenas.
• The rise does not seem to be driven by hormones from the ovaries or testes, although with so few animals this is a very weak test. Larger samples, tests in different social situations, or hormone changes much earlier in life (before or around birth) might show effects.
• As in the wild, pasting is strongly socially facilitated, and sniffing other hyenas and paste marks is what most often sets it off. Unlike reports for wolves, pasting was not linked to immediately preceding aggression.
• The small enclosures and the lack of data on where marks were placed limit any comparison with territorial marking in the wild.
• The modest link between dominance and pasting might disappear at adulthood, or might be found in the wild if pasting is compared with each hyena’s rank within the separate female and male hierarchies.

6. Other technologies, skills or innovations

• Voice-activated tape recorder with an electronic timer marking 30-second intervals.
• Individual hyenas recognized by patterns dyed on their fur with commercial hair dye.
• Halogen security lighting to allow night observation; the authors saw no effect of the lights on behaviour.