Mahenge Scarp Forest Reserve - Frontier-publications.co.uk

Mahenge Scarp Forest Reserve: a biodiversity survey
Butterfly Blendon canopy traps
Five Blendon-style canopy traps were set up at the trapsites, one trap close to one bucket pitfall line, and
two traps on each of the remaining two lines. Traps were baited with fermented banana in the mornings
(usually around 08.00hr). Traps were checked morning and late afternoon. One individual of each species
captured was taken; any ‘repeat species’ butterflies were identified, recorded and released.
Mollusc and millipede quadrats
Molluscs and millipedes were sampled in eight 0.25m x 0.25m quadrats per bucket pitfall line, thus
totalling 24 quadrats per trapsite. Quadrats were established systematically along the lines (see figure 4).
Ten centimetres of soil was removed and placed on a plastic sheet and sifted until completed. All molluscs
and millipedes encountered were collected and preserved.
1
4
6
2
LINE 1
• ↔ ↔ •
2m
2m
7
3 5
8
Figure 4 Diagram of systemmatic positioning of mollusc and millipede quadrats per bucket line
Timed bird counts
Timed-bird species counts were used to assess the relative abundance of birds, based on the assumption
that the birds seen first are the most common species. Suitable habitats were chosen within the forest
reserve and a ‘circuit’ walk of an hour was established. A maximum of three people conducted the bird
count at any one time to minimise disturbance in the area. Walks were optimally conducted at dawn and
dusk, with some data collection at midday, accumulating to 16 hours of survey data. A species list was
collected with a count made each time the species was first positively identified by sight or sound. A
cumulative score was given for each species by counting the scores across all the walks, with a higher
mean score indicating greater observation frequency. The 60 minute fixed time period was broken into 10
minute bands with birds recorded in the first 10 minutes allocated a score of 6, and so on, with a score of
zero for those birds not observed in that count. Data were recorded on standardised sheets.
Animal sign transects
Spoor and other signs of animal presence were assessed along every established transect line through the
Forest Reserve (Figure 3). A 2m strip either side of each transect line was assessed for animal dung, tracks
and paths, as well as other signs such as burrows, diggings, feathers etc. All animal signs were recorded
along with brief geographical and habitat details. To determine identification of indirect evidences, the
knowledge of experienced field assistants was utilised, in conjunction with a Reference Dung Collection
and Walker (1996).
Opportunistic collection and observations
All taxa were also collected and observed on a casual basis throughout the survey period.
Opportunistic collections of amphibians, reptiles, molluscs and millipedes were taken and direct and
indirect observations of birds and larger mammals were recorded to determine the presence of species
otherwise omitted in the standardised techniques. Given the right weather conditions and habitat types,
night searches for tree frogs, chameleons, geckoes and bushbabies were conducted as well as attempting to
record vocalisations of nocturnal fauna, such as bushbabies, hyrax and birds.
Frontier Tanzania Environmental Research Report 107 10