Les G. Underhill

Effectiveness of the global protected area network in representing species diversity

The Fifth World Parks Congress in Durban, South Africa, announced in September 2003 that the global network of protected areas now covers 11.5% of the planets land surface. This surpasses the 10% target proposed a decade earlier, at the Caracas Congress, for 9 out of 14 major terrestrial biomes. Such uniform targets based on percentage of area have become deeply embedded into national and international conservation planning. Although politically expedient, the scientific basis and conservation value of these targets have been questioned. In practice, however, little is known of how to set appropriate targets, or of the extent to which the current global protected area network fulfils its goal of protecting biodiversity. Here, we combine five global data sets on the distribution of species and protected areas to provide the first global gap analysis assessing the effectiveness of protected areas in representing species diversity. We show that the global network is far from complete, and demonstrate the inadequacy of uniform—that is, ‘one size fits all’—conservation targets.

Global gap analysis: Priority regions for expanding the global protected-area network

Abstract Protected areas are the single most important conservation tool. The global protected-area network has grown substantially in recent decades, now occupying 11.5% of Earths land surface, but such growth has not been strategically aimed at maximizing the coverage of global biodiversity. In a previous study, we demonstrated that the global network is far from complete, even for the representation of terrestrial vertebrate species. Here we present a first attempt to provide a global framework for the next step of strategically expanding the network to cover mammals, amphibians, freshwater turtles and tortoises, and globally threatened birds. We identify unprotected areas of the world that have remarkably high conservation value (irreplaceability) and are under serious threat. These areas concentrate overwhelmingly in tropical and subtropical moist forests, particularly on tropical mountains and islands. The expansion of the global protected-area network in these regions is urgently needed to prevent the loss of unique biodiversity.

Optimal and suboptimal reserve selection algorithms

Abstract This paper criticises some reserve selection algorithms that have recently been published in Biological Conservation and have rapidly become enshrined in the principle of complementarity . These algorithms are shown, by means of a counter-example, to be suboptimal. Integer programming techniques, available for 30 years, provide optimal solutions to the reserve selection problem. The paper appeals for closer co-operation between biologists and mathematicians in the development of algorithms.

Flocking as an anti-predator strategy in doves

Abstract The paper reports on a field experiment designed to investigate the initial detection of an aerial predator and the escape response by wild laughing doves Streptopelia senegalensis while feeding as members of flocks of different size. Results indicate that, within certain limits, a large flock has a higher probability of detecting an approaching predator than a small flock. Discussion centres on the gregarious habits of doves in hot arid country, focusing on flocking at water holes.

Collapse of South Africa's penguins in the early 21st century

The number of African penguins Spheniscus demersus breeding in South Africa collapsed from about 56 000 pairs in 2001 to some 21 000 pairs in 2009, a loss of 35 000 pairs (>60%) in eight years. This reduced the global population to 26 000 pairs, when including Namibian breeders, and led to classification of the species as Endangered. In South Africa, penguins breed in two regions, the Western Cape and Algoa Bay (Eastern Cape), their breeding localities in these regions being separated by c. 600 km. Their main food is anchovy Engraulis encrasicolus and sardine Sardinops sagax, which are also the target of purse-seine fisheries. In Algoa Bay, numbers of African penguins halved from 21 000 pairs in 2001 to 10 000 pairs in 2003. In the Western Cape, numbers decreased from a mean of 35 000 pairs in 2001–2005 to 11 000 pairs in 2009. At Dassen Island, the annual survival rate of adult penguins decreased from 0.70 in 2002/2003 to 0.46 in 2006/2007; at Robben Island it decreased from 0.77 to 0.55 in the same period. In both the Western and Eastern Cape provinces, long-term trends in numbers of penguins breeding were significantly related to the combined biomass of anchovy and sardine off South Africa. However, recent decreases in the Western Cape were greater than expected given a continuing high abundance of anchovy. In this province, there was a south-east displacement of prey around 2000, which led to a mismatch in the distributions of prey and the western breeding localities of penguins.

Sexual maturation in squid: quantum or continuum?

A model is presented which tests the representation of the maturity process in terms of gonadosomatic indices (GSI) in chokka squid Loligo vulgaris reynaudii. It assumes that the true maturation process is reflected by the results of histological investigation, which cannot be used in large-scale ecological work in the field. However, the maturity scales used in ecological studies define some morphological categories which can be linked directly to microscopic development. Therefore, the overlap of GSI ranges for each morphological maturity category may be used to judge how well the GSIs represent the histological stages. Results have shown that the overlap is large and that GSI cannot be recommended as adequately reflecting the maturation process in squid. A morphological scale of maturity with possible broad applications in exploited families of squid is proposed as a better representation of the maturation process than GSI.

Index numbers for waterbird populations. I: Review and methodology

This paper reviews methods used to estimate bird population index numbers and proposes a new method. An index number for a year is defined as the ratio of the population size in the year to the population size in the base year. In the context of waterbird populations, the major problem with generating index numbers is the fact that, owing to missing observations at a subset of localities, the total population size in any year is unknown. We suggest a model-based approach to imputing missing observations so that the total population size at the localities may be estimated and used to produce a series of index numbers of the population sizes each year

THE MIGRATION SYSTEM OF THE CURLEW SANDPIPER CALIDRIS FERRUGINEA IN AFRICA

Summary Elliot, C: C. H., Waltner, M., Underhill. L. G., Pringle, J. S. & Dick, W. J. A. 1976. The migration system of the Curlew Sandpiper Calidris ferruginea in Africa. Ostrich 47:191-213. Data on ringing and recoveries of Curlew Sandpiper, mainly from the Cape, South Africa are presented. Possible migration routes to the breeding grounds are considered in the light of these and other recoveries from the rest of Africa. Retraps show that the species exhibits ortstreue and some evidence is presented which suggests that some birds may travel together and stay in the south in the same flock during one and subsequent migrations. Sex ratio statistics show an excess of females. Adults complete a full primary moult in the Cape between September and February, taking about 140 days but there is a lot of individual variation. Data from Mauritania show primary moult starting faster, a month earlier than in the Cape, and arrested moult in a few adults. The difference may be because Mauritanian birds move on further...

Implications for seabirds off South Africa of a long-term change in the distribution of sardine

From 1997 to 2005, the distribution of sardine Sardinops sagax, an important prey item for four seabirds off South Africa, shifted 400 km to the south and east, influencing its availability to breeding birds. It became progressively less available to seabirds in the Western Cape Province, where the number of African penguins Spheniscus demersus breeding decreased by 45% between 2004 and 2006, survival of adult penguins decreased and penguins established a new eastern colony in 2003. In that province, the number of Cape gannets Morus capensis breeding decreased by 38% between 2001/2002 and 2005/2006 and the contribution of sardine to the diet of gannets fell from an average of 40% during the period 1987–2003 to 5–7% in 2005 and 2006. The proportions of Cape cormorants Phalacrocorax capensis and swift terns Sterna bergii breeding in the south of the province increased as sardine moved south and east. In the Eastern Cape Province, the number of penguins breeding halved between 2001 and 2003, whereas after 2002 there was an increase in the number of Cape gannets that bred and in the contribution of sardine to their diet. It is likely that in that province sardine became increasingly available to gannets but remained beyond the shorter feeding range of penguins. Management measures that may mitigate the impacts on seabirds of an unfavourable, long-term change in the distribution of their prey include the provision of breeding habitat where prey is abundant, spatial management of fisheries competing for prey, and interventions aimed at limiting mortality.

POPULATION, BIOMETRICS AND MOVEMENTS OF THE SANDERLING CALIDRIS ALBA IN SOUTHERN AFRICA

Summary Summers, R. W., Underhill, L. G, Waltner, M. & Whitelaw, D. A. 1987. Population, biometrics and movements of the Sanderling Calidris alba in southern Africa. Ostrich 58:24-39. The Sanderling in southern Africa is restricted to coastal habitats. The population during the austral summer was estimated to be 78000. Highest densities occurred along the west coast where the Benguela Up-welling System gives rise to enriched inter-tidal invertebrate communities, partly through the stranding of large kelps. Immigration from the breeding areas took place during September and November. Numbers were highest during mid summer and emigration took place in April. The summer population at Lange-baan Lagoon was biased towards males (72%). The percentage of first-year birds in the summer population fluctuated on a three-year cycle, coinciding with the lemming cycle in the Taimyr Peninsula in Siberia. It is suggested that the cyclic fluctuation is caused by Arctic Foxes, and perhaps other predators, feeding on lemmi...