Hartlaub's Spurfowl - Breeding Habits

Breeding Habits

Hartlaub's Spurfowls appear to be perennially territorial, with variable numbers of boundary call sites demarking each territory. Call-sites are used by territorial pairs on a regular basis, for daily bouts of antiphonal duets. The frequency of use of particular call-sites appears to be influenced more by the presence (vocalizations) of un-mated females on particular boundaries, than by the daily duetting of neighbouring pairs. The mean territory size of Hartlaub's Francolin pairs is 40863.9±12016.1 square metres (n = 12 pairs). Dependent on annual breeding success and offspring survival, the mean population density of the study area during 1983 through 1989 ranged from one bird in 0.82 ha to one bird in 2.04 ha, with an average annual population density of one bird in 1.43 ha. There was no significant difference in outer convex polygon areas determined by call sites and radio-telemetry. However, core ranges and utilization distributions of pairs, and, in particular, the multiple nuclei of different daily activities could only be distinguished by radio-telemetry. The 90% multiple nuclei of seasonal distribution are correlated with patchy distribution of food resources favoured by females, and, whilst rearing young, the distribution of insects, and especially cryptic termites.

Antiphonal duets of territorial pairs are audibly distinguishable, on the basis of temporal and structural differences in the female vocal elements of duets. Territorial pairs use antiphonal duets on a daily basis to advertise their presence, and such calling was most frequent shortly after sunrise. Un-mated females call far more frequently than territorial pairs, often throughout the day, with peaks at shortly after sunrise and before sunset. Playback experiments with the advertising calls of un-mated females within territory boundaries of established pairs, elicited vigorous vocal and behavioural responses from territorial females. Male calls are more conservative than female calls, with females using a wider repertoire of vocalizations.

The mating system of Hartlaub's Spurfowl can be described as a female dominated resource defence monogamy. Perennial territorial resources (food, traditional call-sites, refuge and suitable nest-sites) are primarily defended by female Hartlaub's Francolins. By excluding other females from the vicinity of the resource, the defending female can count on male visitation, life-mating and thus biased mating access with guaranteed fertilization. The pair bond is maintained by ritualised behaviours, including pair-distinct (female initiated) antiphonal duetting and reverse mounting during courtship and incubation. Operational sex ratios are "female skewed" and probably strongly influenced by predation, with noticeably large numbers of strongly- vocal female 'floaters' and a virtual absence of un-mated males. It is unusual that this sex-role reversed monogamy occurs in a species which is strongly sexually dichromatic and dimorphic, with the males more brightly coloured and somewhat larger than females.