Methods
We captured bats over a 12-week period between January
30th and April 14th, 2022, timed to
encompass the short dry season (January to February) and the beginning
of the long-wet season (March to May) in Taita-Taveta County,
south-eastern Kenya (Tuure et al. 2020). We targeted M.
condylurus and M. pumilus bats by netting at building and bridge
roosts thought or known to contain these species (Figure 1). Bats were
captured using mist nets (Ecotone 716/3-12P) set at or above roosting
height (for buildings and bridges), and hand-held butterfly nets
(Hyönteistarvike Tibiale Oy, 65cm net and 550cm telescopic pole) to
block additional, smaller entrance/exit points of buildings not covered
by mist nets (buildings only). Nets were either opened at dusk to
capture bats leaving the roost to forage or opened from approximately
one hour after dusk and operated through the night (17:30-22:30), to
capture bats returning to the roost after foraging. Bats were removed
from the nets immediately to minimize stress or injury. Where feasible,
bats were also captured directly from roosting spaces during daytime
hours by entering the roost space and removing as many as possible. Bats
were held in individual cloth bags and sampled the morning following
capture (for night netting), or the same day (in the case of daytime
roost capture).
Demographic information (sex, age, and reproductive status) and standard
measurements (weight and forearm length) were recorded for all captured
bats. Age (juvenile or adult) was determined by evidence of current or
previous reproduction, size, and ossification of the epiphyses
(juveniles having an incomplete ossification, and adults having a
complete ossification) (Anthony 1988; Monadjem et al. 2007). We
categorised reproductive status into five states for females:
non-reproductive, pregnant and not lactating, pregnant and lactating,
lactating and not pregnant, and post-lactating. Nipples that were
lactating were discernible by a bare patch of skin around an engorged
nipple. Post-lactating nipples were those that appeared visibly engorged
but did not have a bare patch of skin (i.e., not presently lactating but
which might have lactated recently). Gestation was noted by gentle
palpation of the abdomen. If a uterine bulge was present (not palpable
on juveniles, subadults or males), pregnancy was classified as early
(the uterine bulge was palpable but not significant), mid (the foetus
was able to be felt, but the females’ abdomen did not extend past the
ribs), or late (the foetus/bulge was obviously wider than the female’s
rib cage). Females classified as non-reproductive were not detectably
pregnant, lactating or recently lactating (i.e., without enlarged
nipples). Species were identified following Patterson and Webala (2012).
Individuals of appropriate size (with a forearm length between roughly
31-54 mm) were banded (Porzana, Ltd., Icklesham, East Sussex, UK) with
numbered, 2.9 mm, aluminium alloy, split-lipped rings to allow
identification upon recapture. Post-processing, bats were released at
the roost after dusk to reduce risk of predation. Personal protective
equipment was worn at all times during capture, sampling, and release of
bats. Procedures involving bat captures and handling followed
established guidelines (Sikes et al. 2016). To characterise the birth
pulse phenology in M. condylurus and M. pumilus bats, and
evaluate the consistency of reproductive stage per week, we used
chi-squared tests. Comparisons were made per week and included: 1)
numbers of gestating and non-gestating females; 2) numbers of females at
early, mid, and late gestational stages; 3) numbers of lactating and
non-lactating females.