Canopy cover stops aerial wildlife census in the Selous-Mikumi ecosystem

Matambwe, Selous Game Reserve, 6 October 2017 – Fieldwork of a dry season aerial wildlife census in the Selous-Mikumi ecosystem in Tanzania is halted due to unusual and unexpected field conditions. Unusually dense canopy cover is reducing visibility. The census started on September 20 and targeted large mammals in the area of the Selous Game Reserve, the Mikumi National Park, the Selous-Niassa corridor, Wildlife Management Areas and open areas. After surveying a quarter of the more than 110,000 square kilometres’ survey area, the team decided to stop the field work. Widespread early greening of the canopy would lead to inconsistent results. The census will be repeated next year in the dry season. The exact time remains to be determined in consideration of the rainfall and canopy cover.

Unusually dense canopy decreases the percentage of animals that are visible for aerial surveys. Photo: André Baumgarten/FZS
“The Miombo is experiencing an extended and early flush this year due to the unusually long rains,” said Edward Kohi, senior scientist leading the survey team from the Tanzanian Wildlife Research Institute (TAWIRI). Surveys have been conducted regularly since 1976 in the dry season, when the canopy is relatively open. “But this year the situation has changed significantly so that due to the poor visibility we would have difficulties providing reliable estimates and comparing our results to previous surveys,” said Kohi.

Initial results showed that the final estimate for large mammals would not be consistent with previous surveys, and survey scientists from TAWIRI advised the Director of Wildlife, the senior management from the Tanzanian Wildlife Management Authority, the Selous Game Reserve, Tanzania National Parks, Frankfurt Zoological Society and the donor KfW to halt the current survey and postpone further survey implementation.

The decision is based on the outcomes of reconnaissance flights, taking into account observer daily reports and thousands of photos. The long-term rainfall data shows that dry season conditions were strongly modified by the late rains that continued about a month longer than normal. Additionally, unseasonal rainfall at higher levels continued sporadically. This increases tree canopy density and grass height particularly in the west of the ecosystem and the southern parts of the Selous Game Reserve. Also, the Selous Niassa corridor displays an unusually dense canopy for this time of the year. Under these conditions a smaller percentage of animals is visible from the air.

One of the key objectives for this year’s aerial wildlife survey in the Selous Mikumi ecosystem was to provide accurate and reliable data on the population status of elephants and other wildlife species, including trend analysis and population estimates. The Government of Tanzania intended to share these wildlife census results with the UNESCO World Heritage Committee through its “state of conservation report” in February 2018. The census has been implemented as part of the ‘Selous Ecosystem Conservation and Development Program’, funded by the German Government through KfW German Development Bank.

Aerial surveys have been done in the Selous ecosystem since 1976, and are normally conducted every three to four years. Aerial surveys target large mammals. Animals from the size of Impala antelopes and larger can be counted reliably. The observers also record signs of human activities such as livestock and agriculture. Aerial surveys are a vital part of management of large protected areas. They provide trends in numbers of large mammal species, allowing managers to see, for example, the decline or recovery of elephants after increases in protection or other management interventions.

Notes for editors

The Selous Game Reserve is one of Africa’s largest protected areas, with photographic tourism and hunting permitted in designated parts of the reserve. It covers about 50,000 square kilometres which is an area larger than Switzerland and was inscribed in 1982 on the UNESCO World Heritage list for its global significance. In recent times the Selous has been faced by threats including serious declines in its elephant and rhino populations. As a result, it was listed as a World Heritage Site ‘in danger’ in 2014.

The dominant vegetation in Selous Game Reserve is Miombo woodland with a high density and diversity of species. It is a home to large populations of wild dog and lion. There are also important populations of ungulates including hippo, buffalo, sable antelope, Lichtenstein's hartebeest, greater kudu, eland and wildebeest. In addition, there is also a large number of Nile crocodile and over 430 species of birds.

The Selous Ecosystem Conservation and Development Project (SECAD) is co-financed by the German Government through the German Development Bank KfW and the Government of Tanzania. Frankfurt Zoological Society (FZS) and the Worldwide Fund for Nature (WWF) are co-financing and implementing partners of the project. The project objective is effective protection and management of natural resources of the Selous Game Reserve and selected community use zones in adjacent districts in a coordinated manner by SGR management and other stakeholders. Under agreement with the Ministry of Natural Resources and Tourism, FZS is responsible for delivering on strengthening of the management of Selous Game Reserve, WWF supports sustainable ecosystem management of the natural resources in priority parts of the buffer zone and a consultant maintains infrastructure and equipment.

Further information