AfriCat Namibia - Cats Whisper News
Tuesday, 26th June 2018
“Leopards are shy, solitary and very intelligent creatures – far more silent than any of their cousins. They are found in a wide range of habitats from forests to deserts.
At the 17th Congress of Parties of the Convention on Illegal Trade in Endangered Species (CITES CoP17) in Johannesburg, a side event reinforced the fact that leopards (Panthera pardus) need to stay in the spotlight and remain a conservation priority.
The growing threat facing these iconic animals in the wild resulted in their conservation status declining from "Near Threatened" to "Vulnerable" in the June 2016 update of The IUCN Red List of Threatened Species.
Whist it is the most resilient and adaptable of big cats, it has nevertheless seen its historic range decline by up to 67% in Africa and 87% in Asia, due in no small part to pressures exerted by rapidly expanding human populations. This has contributed to extinction of the leopard in 23 of its 85 original range countries.”
The Assessment of Leopard (Panthera pardus) Density and Population Size via a Capture – Recapture Framework in an Island Bound Conservation Area.
Okonjima Nature Reserve, Namibia.
UPDATE AND PROGRESS REPORT
After the initial and in-depth assessment of the leopard population in the Okonjima Nature Reserve via the use of remote camera traps that provided a detailed insight of their demography as well as temporal and spatial distribution patterns, a long-term monitoring program has been introduced. This aims to observe and monitor fluctuations in the composition of the population, as well as shifts and overlaps of home ranges and territories.
AIM OF THE STUDY
To assess the density and population size of leopards (Panthera pardus) in the Okonjima Nature Reserve using photographic capture-recapture sampling and provide scientific data on their demography as well as spatial and temporal distribution patterns.
- To determine leopard density and population size via a capture-recapture framework using remote camera traps.
- To determine the demography of leopards within the Okonjima Nature Reserve.
- To develop a dataset that can be applied as a baseline for comparisons to similar areas.
- To develop a long - term population monitoring programme.
A camera trap survey was conducted in the study area for 250 days from July 2015 – May 2016.
The 20 000 ha Okonjima Nature Reserve was sub-divided into five approximately equally sized blocks of 40 km2 (36.9 km2 ± 5.1 km2).
Each sub-block was sampled sequentially for 50 continuous days and was monitored by a set number of remotely triggered flash cameras (Cuddeback Triple Flash, model C123).
The number of cameras used was proportional to the size of each sub-block resulting in 95 camera trap stations in an effectively sampled area of 184.6 km2 over the entire study period.
A preliminary inspection of the study site was implemented in order to identify suitable camera trap locations. Geographic Position System (GPS) points were taken of every trap site and transferred onto a Google earth satellite map.
To enhance accuracy of abundance estimates and to increase the number of leopards being photographed, camera traps were preferably placed in areas that suggested an elevated frequency of leopard occurrence such as dry riverbeds, riverbanks and/or frequently used roads and pathways.
An inter-trap distance of 1.6 km ± 0.13 km was maintained throughout all five blocks to ensure a complete and regular coverage of the study area and to maximize the capture frequency.
Baited camera stations were used to increase leopard capture frequency. Tall trees at each trap site were selected and baits positioned approximately 1.5 – 2.5 metres above the ground to prevent theft from other carnivores.
A single camera trap was placed two to three metres perpendicular to the branch on which the leopard was expected to occur to access the bait. Cameras were housed in a protective case (CuddeSafe®) to prevent cameras from wildlife damage. Baits were fastened with double wound wire to ensure that leopards don’t remove bait and feed out of sight.
Once triggered, a single camera trap took a series of three consecutive photographs, followed by a delay of six seconds until it was able to trigger again.
Cameras were serviced once a week in order to verify battery status, change of SD cards, renew bait and to ensure the correct functionality of each trap.
Photographs from each trap site were evaluated and leopards were identified via their unique spot patterns. Each individually identified leopard was assigned with a unique identification number and sex and age class were recorded.
SUMMARY OF RESULTS OF LEOPARD POPULATION ASSESSMENT STUDY 2015 / 2016
Leopards were present throughout the entire sampling area. The total sampling effort accumulated 4,566 trap nights and resulted in a total number of 36 captured leopards including 29 adult leopards (14 females, 15 males) and seven dependent juvenile leopards (≤ 18 months).
Leopards were captured a total of 457 times expanded over 250 trapping occasions. Capture frequencies ranged from 1 - 27 captures per individual leopard (12.1 ± 8.1).
Female capture frequencies showed an overall higher capture frequency 15.7± 7.3 within their demographic class when compared to male capture frequencies (12.0 ± 8.5).
14 of the captured 29 adults were fitted with radio collars at the time of capture; equivalent to the total number of collared leopards in the reserve, indicating a 100% detection rate for all collared individuals via the use of remote camera traps.
Leopards were photographed at 90 out of the 95 camera stations. Density was calculated 19.5 leopards/100km2.
Average male home range size was 21.7 km2 ± 10.1 km2 compared to the average female home range size of 8.9 km2 (± 4.3 km2).
Range overlap was observed between and within sexes. Overlap within sexes mainly occurred by dispersing sub-adults in search for territory or offspring that often remains within their natal range.
Home range size varies highly in Sub-Saharan Africa depending on resource availability ranging from 0.5 to 23.8 animals/100km2 (Stander, 1997).
High resource availability and the presence of a boundary fence surrounding the reserve are leading factors resulting in comparably smaller home ranges of the sampled population.
The next phase: Leopard population long-term monitoring programme
In order to observe and monitor dynamics in the composition of the resident leopard population as well as shifts in home ranges and territories, a long-term monitoring programme has been established. For the correct management of an island-bound conservation area, it is fundamental to identify changes in the size and composition of population numbers and to evaluate population trends in terms of resource availability, competition and spatial organization.
The Okonjima Nature Reserve (200 km2) is fully surrounded by an electrified predator proof fence, which creates an enclosed conservation area that protects resident carnivores from all-surrounding farmland on which they'd stand a high chance of human persecution.
Fencing provides an important tool in conservation in limiting the loss of livestock due to carnivores and thus persecution, in response to livestock predation. However, effective fencing also restricts natural dispersal patterns of carnivores and causes differences in their ecology and behavior when compared to their free-ranging counterparts and ultimately might lead to inbreeding, a decline in genetic diversity and local extinction if not managed correctly.
To effectively manage carnivores within a closed reserve, a thorough understanding of their altered ecology is needed to make informed and sustainable management decisions.
To read more about this and other worthwhile projects by Africat Namibia please visit their website at www.africat.org