The Gazelle Has a Problem
It is considered to be the ‘flagship species’ of Ramat Hanadiv but its population is continually dwindling. We met with the researcher Amir Arnon to learn about the trends and the problems, and about innovative research methods in this field
A Disappearing Species
The gazelle population at Ramat Hanadiv has been monitored regularly since 2003 to obtain ongoing estimates of its population size and to track growth trends. Currently, the population includes 50 – 60 individuals, in contrast to 90 individuals twenty years ago. Fifteen years ago, there were there were 10,000 individuals in Israel; however, today there are no more than 3,000. This species – the Palestine mountain gazelle – as its name suggests, has survived almost exclusively in Israel (except for a small population in Turkey). In the more distant past, gazelles could be found in all of the countries around the Mediterranean Basin, from Turkey to northern Saudi Arabia. The current situation is worrying; as their living areas shrink, the potential threats to their population increase, as does our responsibility in Israel to protect this species from extinction.
Amir Arnon, a zoologist and PhD student at the University of Haifa, who has been researching the gazelle population at Ramat Hanadiv in recent years, presents the state of the gazelles at Ramat Hanadiv and of the research on this population.
What are the Reasons for their Extinction?
The gazelles’ disappearance is caused by a number of reasons, including over-reproduction of predators due to excess available food from garbage and human waste, being run over (when trying to cross roads) and illegal hunting. However the main threat to the gazelle population in Israel is massive development that causes habitat destruction by encroaching on open landscapes and fragmentation of populations by roads that divide populations into small groups. The Ramat Hanadiv region is a significant example of this since it is becoming a desert island surrounded on all directions by construction and roads. This situation currently prevents the gazelles from moving freely among open landscapes, for example, between Ramat Hanadiv Nature Park and the Alona Hills. Thus the gazelle populations have been disconnected and isolated, and are therefore under threat of extinction both from random causes such as disease outbreaks and from reproduction within the family, which exposes them to genetic diseases and defects in their future progeny.
When the Gazelles Are Happy, We’re All Happy
The definition of an animal as a flagship or keystone species means that it acts as an important component of the ecosystem and serves as an indicator of its health and quality. This animal influences both those below it and those above it. Therefore, efforts to conserve the entire ecosystem need to be related to its conservation. Since they eat herbaceous plants and shrubs, gazelles impact on the landscape. Their impact is also felt in lesser-known processes, such as dispersal of seeds that they eat or seeds that stick to their coat and are transferred from place to place. Moreover, they serve as prey for other animals and this is an important link in the food chain.
What Kind of ‘Flagship Species’ Is It If It’s Never Seen?
The gazelle is a timid species; therefore, when it hears or smells people, it usually runs away or hides. During certain seasons, mainly the summer, gazelles are active during the evening and night. When it is hot they rest in the shade. Similarly, the dense thickets in Ramat Hanadiv’s Nature Park make it difficult to see them. And indeed, very little is known about the gazelles even today, for example, with regard to how many individuals live at Ramat Hanadiv, and in which areas. We only have estimates, and even these would be difficult to obtain without the use of the advanced tools available today. In the past, direct observations were used – people sat in the field for hours and observed the gazelles. We can lean a lot from this but only a few details. Another, more basic method relied on calculating scat density in certain areas to determine where gazelles prefer to spend their time. These methods are less accurate and based on many assumptions, while the research tools that Amir uses today are among the most advanced tools available.
Scent Stations as Community Centres
We know that animals use their senses to communicate. ‘Scent stations’ are permanent locations frequented by the gazelles for defecating. The gazelles use the scent stations to communicate with each other: via these stations they transfer territorial information, update who is the ‘landlord’, who the area belongs to and how strong he is. Similarly, the females use the scent stations to update the males about their state of sexual receptivity (estrus). Indeed, these stations serve as a kind of community centre for the gazelles. A significant part of Arnon’s research attempts to make the gazelle counting process more accurate; therefore, it was decided to use trail cameras to monitor the gazelles that come to the scent stations (until a decade ago such cameras were not common at all). To this end Arnon installed trail cameras, which are activated when an animal pass by them, at 42 scent stations located around the park, for a period of two months. The choice of scent stations was based on the assumption that these are central locations that increase the chances of observing a gazelle. There are hundreds of scent stations around the entire Park; Arnon selected large scent stations located at relatively equal distances from each other.
During this short and intensive period, about 30,000 photos of gazelles from about 1,500 visits were taken by the cameras. Currently, most of the work involves repeatedly examining each photo to identify the individual appearing in it. With such a respectable amount of photos, it is possible to identify individual gazelles. Identification of individuals is done using external characteristics, such as the shape of the horns, which is unique to certain individuals. To complement the information coming from the cameras, Arnon uses complex statistical models designed to estimate how many individuals were not photographed.
In another study being conducted currently at Ramat Hanadiv by Omer Golan, under the supervision of Dr. Shirli Bar-David from Ben-Gurion University, genetic tests are being conducted on the scats to learn about the size of the gazelle population.
And Let’s Not Forget That Gazelles Need to Eat
In addition to estimating the number of gazelles and their distribution pattern across the Park, Arnon’s research also examines the quality of their nutrition in the Park: What types of foods do they prefer? Is their diet good enough? Does the native food they consume provide them with the required amount of protein? Using genetic and other analyses of the vegetation in the scats he learns about the gazelles’ diets. The research also examines how the presence of cattle in the Park impacts on the gazelles, with respect to competition for food. On one hand, the cows play a very important role in minimising the risk of fire and opening up the dense shrubby areas, but on the other hand, they are big eaters and we must ensure that this does not create a food shortage for the gazelles.
Naturally, studies like these take time and we need to wait patiently until all the results are obtained and analysed so that we can draw operative conclusions. We will continue to follow the research developments and keep you updated.
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