The Importance of Terrestrial Monitoring: A Story of Saigas on the Ground< Back
Article by Kristyna Rysava, Institute of Biodiversity, Animal Health and Comparative Medicine, Graham Kerr Building, University of Glasgow, Glasgow, G12 8QQ, UK. Contact: Kristyna.Rysava@glasgow.ac.uk
This article was published in Saiga News Issue 20 on page 16.
Kazakh people say that those who claim to know where the saigas
are, are liars. Finding saigas is not easy! These nomadic antelopes
are fast runners with no fixed territories and annual movements
exceeding 3,500 kilometres. When on the move, they are capable of
travelling over 100 kilometres a day at speeds of 70 kilometres per
hour. Without doubt, searching for such mobile creatures is a real
Monitoring saigas, is however, a key element of success in their conservation, management and research. Many threats have been imposed upon these antelopes in the last few decades, from poaching and habitat loss to environmental abnormalities and devastating disease outbreaks, as recently seen with a series of mysterious large-scale die-offs. It is through effective monitoring and understanding where, when and why changes in saiga populations occur that conservationists are able to develop informed and effective interventions.
Remote sensing through deployment of either GPS or radio-telemetry collars is a common technique for monitoring highly mobile species. The data collected can provide detailed information on movement and spatial distributions. With rapid advances in these technologies, ecologists are now employing satellite tracking more than ever. Yet, for fine-scale observations such as the identification of nearby predators and other determinants of behaviour, terrestrial monitoring is more powerful. So what kind of information can we gather using ground monitoring and what will it teach us, especially in an environment as challenging as Central Asia's?
The saiga's homeland is vast; however, their distribution dramatically changes throught the year. In spring, after spending winter in the dry deserts of the south in refuge from harsh winter conditions, saigas travel back north in search of better foraging grounds (Figure 1i).
Figure 1(i). Seasonal distribution of three populations of saiga antelope in Kazakhstan: Ural (north-west), Ustyurt (south-central) and Betpak-dala (north-central; highlighted in the black oval) from 2008 to 2012. Each point represents a single ground observation event that usually consisted of multiple individuals. The summer range, shown in red, was determined using location points collected from May to September, with winter grounds, in blue, showing December to March locations. For all populations, we can see a clear partition between summer and winter pastures. As an exception, a fragment of the Betpak-dala population in the north-east (highlighted in the red oval) appears to be present in the area continually throughout the year.(ii). Distribution of saigas and their predators during the breeding season based on ground observations collected in May from 2008 to 2012. The inset shows that despite gray wolves being the most common predator overall, steppe eagles were the most frequently recorded predator observed around the calving grounds.
On their return journey, between the winter and summer pastures, they give birth over a two-week period in May. During calving, these antelopes are most vulnerable to predation (Figure 1ii). Wolves are their main predators, but even smaller predators such as eagles, vultures and foxes will try to attack calves. Sightings of saigas not only provide insights into their seasonal and spatial distribution, but also inform researchers about behavioural and group characteristics. For example, whilst we would expect saigas to be constantly on the move, a small outlying herd in the northwest of the Betpak-dala range appears to remain resident year-round (Figure 1i). For many ungulates it is not uncommon for different populations to show both life-history strategies; migration as well as residency, depending on proximate conditions (e.g. wildebeest, white-tailed deer).
Saigas are both mobile and highly gregarious. Average herd size can drastically change depending on season, ranging from tens to thousands of individuals. Most notably during periods of calving, migration and rut, saigas tend to aggregate; in social species the benefits of herding behaviour are substantial. Critically, herding provides greater protection and early warning against predators. Large and dense herd formations are especially important during the breeding season when defenceless calves are vulnerable to opportunistic predators eagerly waiting for a spring feast. Previous research (Milner-Gulland 2001) suggests that due to declining numbers of saigas, individuals are unable to find large calving groups, leading to increased predation risks and higher calf mortality. From 2009 to 2011 significantly smaller saiga herds were recorded during calving in May than in the winter months (Figure 2).
Figure 2. Monthly time-series of saiga herd size; minimum, maximum and average (mode). The average herd size shown as a red line appears to be rather low throughout the monitoring period (April 2008 to December 2012). Zero values represent months when monitoring was not undertaken. From September 2009 to January 2010, herds of up to 15,000 individuals were encountered (highlighted in the dark polygon), but large herds were also seen in December 2010 and November 2011. The higher abundance of animals during winter months compared to the calving season (May) suggests high winter mortality. Alternatively, low numbers recorded in spring might indicate inaccurate estimates of the calving aggregations due to counting difficulties associated with such large numbers of individuals.
Whilst the importance of herding is unambiguous, the effects of sex and age composition on population dynamics are only now becoming better understood. Loss of males might not be seen to be a pressing threat to saigas. As polygynous species, during the rut season males gather harems of 2 - 15 females that they defend from rivals and subsequently mate with. So having fewer males is no big deal, or is it?
Selective hunting of males for their horns and larger hides reduced the sex ratio of the Kalmykian population to, at the most extreme, one male per 100 females (Milner-Gulland et al., 2003). The insufficient numbers of prime-aged males led to failure to conceive and population recruitment was significantly reduced. As young males are unfavourable and inexperienced partners, often unable to successfully breed, the absence of prime-aged males contributes to diminished reproductive capacity.
In this study, ground-based observational data was provided by ACBK, and analysed by the author to explore the status and trends of saigas in Kazakhstan from 2008-12. Terrestrial monitoring and data collection was carried out by 45 observers in total, mostly governmental rangers and ACBK field staff. There was no indication of sex/age related reproductive collapse in Kazakhstan between 2008 and 2012, possibly due to a substantially larger population compared to Kalmykian saigas (Figure 3).
Figure 3. Sex ratio of saiga populations in Kazakhstan based on terrestrial monitoring conducted between 2008 and 2012. Both full year data (i) and observations collected during rut (December) (ii) suggest that the abnormal bias toward females (>20 females per male) previously documented in Kalmykia did not occur in Kazakhstan during this period. In 2011 no monitoring was carried out in December during the rut.
However, the data should be interpreted with caution as neither sex nor age is easy to determine from visual observations. (Figures 3 and 4). Animals are either clumped together or too far away for individual identification, and young individuals can be indistinguishable from adults; for instance, immature males without fully grown horns look similar to females. Given these uncertainties, it is hard to draw conclusions.
It is a true art to keep an eye on saigas! Monitoring the herds in Kazakhstan is a particular challenge, with difficult logistical and climatic conditions, and limited financial and human resources. The low consistency and coverage of data from ground monitoring makes it currently of limited use for analysis of the mechanisms behind population trends, with inevitable biases and uncertainties according to the season and field conditions. Terrestrial surveys are, however, irreplaceable, providing precious insights into animal behaviour, population trends and problems such as landscape alternations that impact on saiga ecology. From monitoring huge areas through to detecting critical bottlenecks and developing strategic interventions, conservationists need to be able to identify threats and act fast to minimize impact.
Ground monitoring undoubtedly represents a cost-effective tool for real-time management implementation, though there is potential for improvements. However, survey programmes like this one are under constant threat of being terminated due to budget limitations and funding cuts, often before improvements in data collection techniques can be implemented and yield essential long-term datasets. Instead of getting axed, programmes should be valued for the data they produce and strengthened for more efficient monitoring. The way is always there; we shall see how large the will is.
Figure 4. Age composition of the saiga population from 2008 to 2012. Many individuals remained unidentified (grey). Precise differentiation between sex and age classes in saiga antelope is not easy to achieve, especially from a distance. Therefore, the data presented here and in Figure 3 should be interpreted with caution.