The importance of roads to South African partridges and francolins

04 Nov 2008 - By Nic Lowry & Aldo Berruti

Introduction

Every gamebird enthusiast knows that francolins and partridges appear on roads in the early morning and late afternoon, and are usually absent from roads during the middle of the day.

We have been studying and monitoring Greywing Partridge Scleroptila africanus and Swainson’s Francolin Pternistis swainsonii at Fairview Farm, Vrede District since 2006. Many hours of personal observation have generated possible reasons as to why this behaviour occurs.

In addition, we have observed that the distribution of Greywing Partridge coveys on Fairview Farm is concentrated along the untarred S13 district road which bisects the farm, as well as the larger, regularly-used farm roads. Is this distribution pattern purely coincidental in that the road cuts through the primary centre of distribution, or is it a result of the road?

This article presents theories as to why these gamebirds use roads in early morning and late afternoon, and why their distribution may be concentrated along roads. In the next newsletter, we will describe how accurate surveys of Greywing Partridges can be undertaken using dawn surveys to locate calling coveys and birds on roads.

The need for open space for social species for visual signalling and interaction

Viljoen (2005 p.259) states that francolins and partridges require open ground for social behaviour and for dust-bathing and that on most farms, this is provided by farm roads. We are in agreement with this although it does not explain the timing of their appearance on roads in early morning and afternoon.

The dawn and dusk occurrence of partridges and francolins on roads

It is suggested that the occurrence of gamebirds on roads early and late in the day is related to the timing of need for social interaction, feeding and maintenance behaviour (such as sunning and preening). Viljoen (2005 p 259) also states that francolins and partridges need open ground for drying feathers after heavy dew, and by implication, this would help explain their early morning presence on roads, but not in late afternoon. Little & Crowe (2000) report that the Swainson's Francolin venture into open ground for feeding and dust-bathing in early morning and afternoon.

All birds spend substantial amounts of time in maintenance activities such as feather care, sunning and dust-bathing. Observations of Greywing Partridge and Swainson’s Francolin in winter at Fairview supports the view that sunning is part of the function of their early morning occurrence on roads, at least in winter. For example, shortly after dawn on a frosty morning in June 2008, two ¾ grown Swainson’s Francolin chicks were observed standing still, whilst facing into the sun with feathers raised, a typical sunning behaviour in birds, whilst ignoring a nearby vehicle. The raised feathers allow the sun’s rays to penetrate the feather coat.

To more fully explain the need for early morning and late afternoon use of roads for social interaction, we present the Face Book Time theory.

Greywing Partridges live in coveys numbering from 3 - 20 birds in the Vrede district. Coveys break into pairs when breeding. The social structure of Greywing Partridge coveys has not been reported in detail. However, it may be expected that Greywing Partridge coveys have a strong social structure within the covey, with social status influenced by gender, age and dominance ranking. Typically, social animals affirm their status in ongoing one-on-one interactions within the group. Early morning is particularly important for such interactions after a night’s sleep, as individuals reaffirm social status, individual rank and bonds, or perhaps challenge competitors. A second, usually lesser peak of such activity takes place at the end of a day’s activity in diurnal animals prior to sleep. Critically, for a ground-dwelling grassland species, open spaces facilitate such social interaction because individuals can see other individuals unobstructed by vegetation. Open roads are ideal interaction sites.

Greywing Partridge coveys typically call soon after first light and neighbouring coveys will often call in response to each other (Little & Crowe 1992). This is typical vocal behaviour by social groups in defence of their territories and advertises their presence in relation to surrounding coveys. Such territorial behaviour in the early morning and late afternoon supports the theory of Face Book Time. In the same way that individuals affirm or try to change their social status, each covey affirms its territory in relation to surrounding coveys.

Swainson’s Francolin also typically calls at dawn and dusk, and males will frequently call from conspicuous perches such as trees and fence posts (Little & Crowe 2000). This behaviour is predicted by Face Book Time theory. However, because Swainson’s Francolin occur singly, in pairs or family groups of up to six birds, there should be a smaller requirement for social interaction because there are fewer individuals in the social group. The fact that they still occur on roads in early morning and evening as do the more social Greywing Partridges is evidence for the fact that their occurrence on roads has a number of advantages in addition to the need for social interaction. Such peaks in activity and vocal behaviour are probably generally typical for other South African partridges and francolins.

Reasons to avoid roads during the middle of the day

There are at least two possible reasons why gamebirds might avoid roads later in the day – firstly vehicle and other traffic is a disturbance. Greywing Partridges typically hide at the approach of a vehicle. Ongoing vehicle disturbance must of necessity mean fewer encounters during periods of higher traffic activity. However, this would not explain their reappearance (although less frequently in the morning) in late afternoon on the roads.

During the midday heat, birds will shelter under cover, and so birds would avoid roads during the middle of the day, particularly in summer.

Occurrence at higher densities along roads

Greywing Partridge coveys at Fairview Farm are concentrated along a major district road and large farm roads, with coveys occurring on both sides of this road. Whilst there is a case for arguing that their dense occurrence along the district road is an accident of topography as the district road passes between high-lying koppies usually considered highly suitable for Greywing Partridge, other explanations suggest that the road itself results in a concentration of coveys.

Habitat diversity. Typically road verges are managed differently to the adjacent fields. Road verges are often burnt as firebreaks, and thus burning may take place earlier than general burns or runaway fires. Grazing pressure on road verges is often much less and verges often have far longer grass than adjacent fields. Runoff from the roads may create more lush growth next the road. Thus the road verge may provide either food or shelter not available in adjacent fields. Roads and their verges will often add to the diversity of habitat within the territory of a covey.

Fires. There were huge runaway fires in the Vrede district during the winter of 2007. One fire burnt through part of the high-density area occupied by Greywing Partridge coveys on Fairview farm. Subsequent to the fire, the Greywing Partridge coveys vacated burnt lands. They were observed feeding in burnt areas during the day, but were typically very skittish and usually ran to grass cover if they were visible in the open. It was apparent that burnt areas are largely no-go areas for Greywing Partridges after a burn until vegetation growth occurs. Depending on the timing of a burn, such a period could be from 2-4 months. However, if part of a territory is not burnt, a covey can continue to occupy its territory and venture into burnt areas for feeding, until regrowth allows full reoccupation of the territory. Roads can act as very effective firebreaks and fires will often be halted at roads, either by counter-burns or simply because the fire cannot jump the road. Greywing Partridge coveys hold relatively stable territories, and there is a high risk that over a period of years, any one territory will be entirely burnt out by a fire. However, if that territory crosses a road, there is a much greater chance that part of the territory will be unburnt. Thus a territory that straddles a road is far more stable in the long term, and less likely to be entirely burnt out at some stage. Thus the diversity of habitat offered by a territory that crosses a road, including partial protection from fire, may make these territories more stable over time.

Feeding

It is suggested that under some conditions, seeds and grains may be more available on roads than in natural veld or grain lands for two reasons. Firstly, seeds from wild grasses blown onto roads, and other natural foods such as insects, may be more visible on bare earth than in the veld. Improved visibility allows the gamebird to scan a far wider area effectively than in grasslands with denser cover, allowing ready identification of food items on the road. In addition to naturally-occurring seeds, the spilling of commercially grown crops such as maize along roads during transport after harvesting, may provide a food bonanza for limited periods of the year. Obviously, this comment applies only to commercial grain-growing areas. Also, as argued below, there may an increased availability of food of certain types along the road verges. The reason that the partridges occur on roads early and late in the day is that these are typically periods of maximum feeding activity in birds.

Conclusions

It is suggested that Greywing Partridges occur on roads early and late in the day because it provides better visibility and therefore more effective social behaviour, feeding and maintenance behaviour.

It is suggested that Greywing Partridge territories are concentrated along roads at Fairview Farm because of the habitat diversity offered by road verges, increased stability of habitat in relation to fires and increased food supplies.

References

Little, R.M. & Crowe, T.M. 1992. Vocal behaviour of Greywing Francolin can be used to estimate population density. Ostrich 63: 98-109.
Little, R.M. & Crowe, T.M. 2000. Gamebirds of Southern Africa. Struik, Cape Town.
Viljoen, P.J. 2005: AGRED’s Gamebirds of South Africa - Field Identification and Management. Johannesburg: AGRED.