DOI: 10.5061/dryad.j3tx95xdj
title: Fragmented landscapes affect honeybee colony strength at diverse spatial scales in agro-ecological landscapes in Kenya

description: Landscape fragmentation and habitat loss at multiple scales directly
 affect species abundance, diversity and their productivity. There is a
 paucity of information about the effect of the landscape structure and
 diversity on honeybee colony strength in Africa. Here, we present new
 insights into the relationship between landscape metrics such as patch
 size, shape, connectivity, composition and configuration and honeybee
 (Apis mellifera) colony strength characteristics. Remote sensing-based
 landscape variables were linked to honeybee colony strength variables in a
 typical highly fragmented small holder agro-ecological region in Kenya. We
 examined colonies in six sites with varying degrees of land degradation,
 during the period from 2017 to 2018. Landscape structure was first mapped
 using medium resolution bi-temporal Sentinel-1 and Sentinel-2 satellite
 imagery with an optimized random forest model. The influence of the
 surrounding landscape matrix was then constrained to two buffer distances
 i.e., 1 km representing the local foraging scale and 2.5 km representing
 the wider foraging scale around each investigated apiary and for each of
 the six sites. The results of zero-inflated negative binomial regression
 with mixed effects showed that lower complexity of patch geometries
 represented by fractal dimension and reduced proportions of croplands were
 most influential at local foraging scales (1 km) from the apiary. In
 addition, higher proportions of woody vegetation and hedges resulted in
 higher colony strength at longer distances from the apiary (2.5 km).
 Honeybees in moderately degraded landscapes demonstrated the most
 consistently strong colonies throughout the study period. Efforts towards
 improving beekeeper livelihoods, through higher hive productivity, should
 target moderately degraded and heterogeneous landscapes, which provide
 forage from diverse land covers. 
description: Standard Langstroth hives were used for this study. Each of the
 hives were labeled randomly from 1 to 10 in each apiary and subsequently
 the frames in the hives labeled 1 to 10 with each side of the frame
 labeled A or B. Initially, 60 hives were setup for this study, i.e., 10
 hives per site. However, throughout the study period, we only inspected
 and sampled 30 hives (i.e., colonies) which were the only ones occupied by
 natural swarms as observed during our first field data collection. Visual
 estimates from two observers were used, as this method is less disruptive
 compared to using empirical measurements such as weight of the honeybees
 (Delaplane et al, 2013a). All the data measurements were conducted during
 the early hours around 07h00 and 08h00 local time (Greenwich Mean Time:
 GMT + 3) of the day to control for the foraging activities of honeybees,
 which might affect the observations, especially of the adult honeybee
 population. Each of the occupied hives was lightly smoked, opened and
 frames containing combs were sequentially removed and examined. The
 estimated percentage coverage of each frame side by the target resource
 (adult population, sealed and open brood, eggs, honey and pollen) was
 visually done. Honeybee colony strength was estimated following Delaplane
 et al. (2013) and Imdorf and Gerig (2001) Liebefeld protocol. 
 In order to generate the landscape fragmentation indices, a
 honeybee habitat map was generated from a fused bi-temporal Sentinel-1 and
 a single season Sentinel-2 dataset ((European Space Association (ESA),
 2017), which had an overall accuracy of 86% (Ochungo et al., 2019),
 (Figure 1). Fragmentation indices were thereafter generated from the
 habitat map at various spatial scales ranging from 0.5 km to 3
 km.