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Long-term Monitoring of Gazelles and Partridges

Amir Arnon, Bill Woodley, Hila Shamoon and Liat Hadar

The mountain gazelle (Gazella gazella) and the chukar partridge (Alectoris chukar) are used as bio-indicators sensitive to changes in the composition of their shrubby (garrigue) environment and the landscape formation of their main habitat; therefore, these species were chosen as key species for long-term monitoring.

chukar

Monitoring began in November 2003 as part of a long-term ecological research (LTER) study of a range of selected variables, which was set up and began operating that same year, and has continued until today.

The aim of the survey is to monitor temporal changes in their population size, demography, and ability to produce offspring.

The data are collected throughout the year, using direct observations along a transect on two mornings and two evenings per month.

The transect is 12 km long, covers most of the park’s area and represents the range of factors that may affect population distribution, such as height above sea level, aspect, slope, vegetation type, grazing management, land use, and proximity to roads and built-up areas. The starting point of the survey is rotated. For every observation we record the coordinates, the date and time, the weather conditions, and the sex, age (young/mature) and number of individuals in the group.

Gazzel_01

The data were analysed gradually, at three points in time: 2009, 2015 and 2019

2003–2009 Results

These data were analysed by the ecologist, Amir Perlberg. A Hebrew version of the full report can be found here.

Although there was an increase in the estimate of the general population size in 2009, with respect to the previous year, the gazelle population at Ramat Hanadiv appears to have experienced a general decreasing trend during the monitoring period (2003–2009).

We note that while the number of males in recent years has remained stable, there has been a worrying decrease in the number of females and young individuals.

When examining the seasonal impact on the estimate of gazelle population size, it was found that the number of gazelles observed in winter was higher than in spring or summer, probably due to behavioural effects. In contrast to the gazelles, the partridge population at Ramat Hanadiv appears to have remained stable among years; the highest number of individuals is observed in summer and autumn, with intermediate numbers in winter, and lowest numbers in spring.

In addition, the impacts of cattle grazing, anthropogenic factors and topographic characteristics on the spatial distribution patterns of the gazelles and the partridges are examined and presented.

2003–2015 Results

The gazelle data only were analysed by the ecologist, Dr. Hila Shamoon, and can be found in the executive summary here. The results of the analysis show that during the years 2004–2012 there was a decrease in the size of the gazelle population at Ramat Hanadiv, while from 2012 there was a trend of recovery.

We note that during 2012 changes were made in the way the survey was conducted (horseback riding was replaced by driving an off-road vehicle), and a wildlife feeding station (that had operated until 2012), which had probably encouraged the predator community, particularly the jackals, was closed.

2004–2021 Results

The survey dataset was analyzed by ecologist Amir Arnon.

Trends in the gazelle population are presented in the  graph:

The data indicate that after a recuperation of the gazelle population between 2012 and 2015, it remained stable for a few years. However, it seems that since 2018, there is a constant decline in gazelle numbers. Other data suggest that this is related to an increase in the population of golden jackals (Canis aureus) in the park during those years. To understand the factors for the increase in jackal population in the region, we have initiated research on the topic. At this stage, it seems that jackals in the region of Zikhron Yaakov, Binyamina, and Ramat Hanadiv have plenty of available food, which is mostly comprised of agricultural waste, cat food which is given in an uncontrolled manner, and garbage. Once we identify the various food sources, we will take actions to diminish them, thus reducing jackal densities, and helping gazelles and other wildlife populations in the park, to recuperate.

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