Introduction

Species which show unpredictable movements and concentrations pose considerable challenges for the policy and legislation framework of conservation action for such species, as well as for their implementation of conservation action.

This article examines the example of the Namaqua Sandgrouse Pterocles namaqua in southern Africa – looking at problems of definition, biological understanding and of implementing conservation action. It resurrects the proposed Memorandum of Understanding (MOU) between three southern African nations for the conservation of the Namaqua Sandgrouse.

Definitions of migration include a constraint of predictability. Thus the definition of the Convention on Migratory Species is “Migratory species means the entire population or any geographically separate part of the population of any species or lower taxon of wild animals, a significant proportion of whose members cyclically and predictably cross one or more national jurisdictional boundaries”. A definition of a nomadic species is one which wanders erratically usually in reference to rainfall and/or food.

However, for some species, it is not simple to determine whether movements are to be regarded as migratory or nomadic. Several bird species which occur in the vast and sparsely inhabited interior of Southern Africa show unpredictable movements at a local level. This region is characterized by rainfall which is variable in timing and extent, which drives the unpredictability.

For example, the Namaqua Sandgrouse is described as “nomadic; southern populations partially migratory…” The Namaqua Sandgrouse is regarded as showing regular east-west movements related to breeding within northern South Africa and Botswana whilst being more sedentary in Namibia. Yet these movements were not revealed by the series of detailed two-monthly maps of this species as shown in the Atlas of Southern African Birds based on data collected over a decade. This analysis was based on a considerable numbers of observations, yet failed to show these patterns, probably because of the interannual variation in rainfall and hence movements, and which were masked when lumped together. The current understanding of the movements of the Namaqua Sandgrouse was later elucidated by detailed studies on the Namaqua Sandgrouse but further work on the extent and predictability of movement is required.

Another example is the Black-winged Pratincole, which breeds in Eurasia from the Black Sea to Kazakhstan and winters in the interior of Southern Africa from the Highveld grasslands of South Africa in the east to Botswana and Zambia in the north and west. The species usually occurs in flocks, but its occurrence locally is utterly unpredictable.
The definition of whether these two species are migratory or nomads depends entirely on the scale at which movements are considered. At the continental scale the movement of Black-winged Pratincole is regular and cyclical, moving from Northern Hemisphere breeding areas to Southern Hemisphere wintering areas. There is no question that at this scale, the Pratincole is a migratory species however unpredictable at a local level.

The Namaqua Sandgrouse is also a migratory species. At a subcontinent scale, it shows regular, annual movements from west to east in conjunction with rainfall patterns. Again, at a local scale, their occurrence and abundance is far less predictable.

Further problems in biological understanding

Both of these species are excellent examples of the technical difficulties in understanding the biology of species which breed and occupy sparsely populated areas with variable environmental conditions.

The Black-winged Pratincole was estimated to number between 25 000 and 45 000 birds until recently. In 1990, a single flock in the eastern Free State was estimated to number 250 000 – 800 000 birds, whilst an observation of a migratory movement of this species in Zambia in 1977 estimated 100 000 to one million birds. More recently, a waterbird count on the Vaal Dam (with a shoreline >1000 km) in central South Africa, produced a count of 75 000 Black-winged Pratincoles, a species not recorded in three previous counts. It is very difficult defining its global population size (a basic population parameter), let alone determining population trends.

Similarly, the unpredictability of the Namaqua Sandgrouse at a local scale from year-to-year makes evaluation of population size and trends very difficult.

Problems in implementation of conservation action

Unpredictability at the local scale poses formidable conservation and management problems from year to year. The usual system of protected areas for conservation of core areas of high abundance or breeding concentrations cannot be implemented. A further problem lies in the practical difficulties of providing an effective enforcement process (if suitable legislation exists) or even providing an educational and awareness program for the highly scattered and isolated communities living in these areas. This is exacerbated in regions such as Africa in which the infrastructure for conservation and education are inadequate compared to the western hemisphere.

International Agreement on Sandgrouse in Southern Africa.

With this background of the difficulties of understanding the biology of such species, the difficulties of developing a policy framework and legislation, and the practical difficulties of enforcing legislation or creating voluntary compliance with legislation; it is worth remembering a draft Memorandum of Understanding (MOU) exists for the Namaqua Sandgrouse. During the 1990s, considerable progress was made by Botswana, South Africa and Namibia on the MOU.

The development of the MOU was sparked in part by perceptions of declining populations, although it is an abundant species, and the impact of hunting on population size. There are two particular problems relating to its utilization through hunting. The birds are usually hunted from fixed points as they fly to waterholes to drink. Although there are well-known specific guidelines for ethical and sustainable hunting, the species is vulnerable to unscrupulous exploitation perhaps resulting in unsustainable harvests. Secondly, the sympatric Burchell's Sandgrouse Pterocles burchelli usually breeds during the hunting season for Namaqua Sandgrouse. The impact of incidental harvesting of Burchell’s Sandgrouse during its breeding season is more likely to result in unsustainable and ethically unacceptable harvests. These issues are set against the fact that global population trends for both species may be driven by macro-scale climatic patterns or land-use patterns which are immensely difficult to elucidate versus the immediate and visible hunting harvests.

International co-operation via this MOU could contribute enormously e.g. through a network of observers to understanding the biological basis for movements of this species. Ideally, if suitable technology were available satellite tracking of some 10-20 individuals would provide valuable additional information.

Implementation of the MOU could prove to be a ground-breaking African example of international co-operation on a species inherently difficult to manage and conserve.

Implementation of the sandgrouse MOU

Ultimately successful conservation of the sandgrouse will be reliant on voluntary compliance, as the cost of infrastructure to enforce unpopular regulations is beyond the capacity (finance and staffing) of provincial and even national conservation departments in this region. Voluntary compliance will depend on the setting of credible regulations based on sound biological understanding, and which promote the vision of long-term sustainable utilization and conservation of this species throughout its range. Implementation will depend to a large degree on a far -reaching awareness and educational program reaching the isolated and sparsely distributed communities.

It is time to look again at the draft MOU for the Namaqua Sandgrouse, which provides a solid foundation. I propose that international negotiations are reinitiated. Perhaps an understanding that implementation of such an agreement is to a large degree dependent on the co-operation and involvement by civil society would lend new impetus to governments who might be reluctant to take on new international commitments.

References

1. Hockey, P.A.R., Dean, W.R.J. & Ryan, P.G. (Eds). 2005. Roberts – Birds of South Africa, VII ed. Trustees of John Voelcker Bird Book Fund, Cape Town.
2. Little, R.M. 1997. Namaqua Sandgrouse. In Harrison, J.A. et al. (eds) The Atlas of Southern African Birds Vol.2: 494-495.
3. Lloyd, P., Little, R.M., Crowe, T.M. & Simmons, R.E. 2001. Rainfall and food availability as actors influencing the migration and breeding activity of Namaqua Sandgrouse Pterocles namaqua. Ostrich 72: 50-62.
4. Malan, G., Little, R.M. & Crowe, T. 1994.Temporal and spatial patterns of abundance and breeding activity of Namaqua Sandgrouse in South Africa. S. Afr. J. Zool. 29: 162.
5. Viljoen, P.J. 2005. AGRED’s Gamebirds of South Africa Field Identification and Development. African Gamebird Research Education and Development Trust, Johannesburg.
6. Hagemeijer, W.J.M. & Blair, M.J. 1997. The EBCC Atlas of European Breeding Birds: their distribution and Abundance. Poyser, London.
7. Du Plessis, G.J. 1995. Large aggregations of Black-winged Pratincoles Glareola nordmanni in eastern Free State. Ostrich 66: 40-41.
8. Aspinwall, D.R. & Conant, P. 1977. Palearctic migrants. Newsl. Zambian Ornithol. Soc. 7: 98.
9. Avian Demography Unit 2006. Citizen Science Again. Africa Birds & Birding 11 (2): 79.

For more information about African Gamebirds contact Dr Aldo Berruti, Director, African Gamebird Research Education and Development Trust (AGRED), email agred@netdial.co.za