Assessing roost disturbance of straw-coloured fruit bats (Eidolon helvum) through tri-axial acceleration

The disturbance of wildlife by humans is a worldwide phenomenon that contributes to the loss of biodiversity. It can impact animals' behaviour and physiology, and this can lead to changes in species distribution and richness. Wildlife disturbance has mostly been assessed through direct observation. However, advances in bio-logging provide a new range of sensors that may allow measuring disturbance of animals with high precision and remotely, and reducing the effects of human observers. We used tri-axial accelerometers to identify daytime flights of roosting straw-coloured fruit bats (Eidolon helvum), which were used as a proxy for roost disturbance. This bat species roosts on trees in large numbers (often reaching hundreds of thousands of animals), making them highly vulnerable to disturbance. We captured and tagged 46 straw-coloured fruit bats with dataloggers, containing a global positioning system (GPS) and an accelerometer, in five roosts in Ghana, Burkina Faso and Zambia. Daytime roost flights were identified from accelerometer signatures and modelled against our activity in the roosts during the days of trapping, as a predictor of roost disturbance, and natural stressors (solar irradiance, precipitation and wind speed). We found that daytime roost flight probability increased during days of trapping and with increasing solar irradiance (which may reflect the search for shade to prevent overheating). Our results validate the use of accelerometers to measure roost disturbance of straw-coloured fruit bats and suggest that these devices may be very useful in conservation monitoring programs for large fruit bat species.info:eu-repo/semantics/publishedVersio

Overall Dynamic Body Acceleration in Straw-Colored Fruit Bats Increases in Headwinds but Not With Airspeed

Atmospheric conditions impact how animals use the aerosphere, and birds and bats should modify their flight to minimize energetic expenditure relative to changing wind conditions. To investigate how free-ranging straw-colored fruit bats (Eidolon helvum) fly with changing wind support, we use data collected from bats fit with GPS loggers and an integrated triaxial accelerometer and measure flight speeds, wingbeat frequency, and overall dynamic body acceleration (ODBA) as an estimate for energetic expenditure. We predicted that if ODBA reflects energetic expenditure, then we should find a curvilinear relationship between ODBA and airspeed consistent with aerodynamic theory. We expected that bats would lower their airspeed with tailwind support and that ODBA will decrease with increasing tailwinds and increase with wingbeat frequency. We found that wingbeat frequency has the strongest positive relationship with ODBA. There was a small, but negative, relationship between airspeed and ODBA, and bats decreased ODBA with increasing tailwind. Bats flew at ground speeds of 9.6 ± 2.4 ms−1 (Mean ± SD, range: 4.3–23.9 ms−1) and airspeeds of 10.2 ± 2.5 ms−1, and did not modify their wingbeat frequency with speed. Free-ranging straw-colored fruit bats therefore exerted more total ODBA in headwinds but not when they changed their airspeed. It is possible that the flexibility in wingbeat kinematics may make flight of free-ranging bats less costly than currently predicted or alternatively that the combination of ODBA and airspeed at our scales of measurement does not reflect this relationship in straw-colored fruit bats. Further work is needed to understand the full potential of free-ranging bat flight and how well bio-logging techniques reflect the costs of bat flight

Protected Areas in Tropical Africa: Assessing Threats and Conservation Activities

Numerous protected areas (PAs) have been created in Africa to safeguard wildlife and other natural resources. However, significant threats from anthropogenic activities and decline of wildlife populations persist, while conservation efforts in most PAs are still minimal. We assessed the impact level of the most common threats to wildlife within PAs in tropical Africa and the relationship of conservation activities with threat impact level. We collated data on 98 PAs with tropical forest cover from 15 countries across West, Central and East Africa. For this, we assembled information about local threats as well as conservation activities from published and unpublished literature, and questionnaires sent to long-term field workers. We constructed general linear models to test the significance of specific conservation activities in relation to the threat impact level. Subsistence and commercial hunting were identified as the most common direct threats to wildlife and found to be most prevalent in West and Central Africa. Agriculture and logging represented the most common indirect threats, and were most prevalent in West Africa. We found that the long-term presence of conservation activities (such as law enforcement, research and tourism) was associated with lower threat impact levels. Our results highlight deficiencies in the management effectiveness of several PAs across tropical Africa, and conclude that PA management should invest more into conservation activities with long-term duration.Additional co-authors: Jef Dupain, Atanga Ekobo, Manasseh Eno-Nku, Gilles Etoga, Takeshi Furuichi, Sylvain Gatti, Andrea Ghiurghi, Chie Hashimoto, John A. Hart, Josephine Head, Martin Hega, Ilka Herbinger, Thurston C. Hicks, Lars H. Holbech, Bas Huijbregts, Hjalmar S. Kühl, Inaoyom Imong, Stephane Le-Duc Yeno, Joshua Linder, Phil Marshall, Peter Minasoma Lero, David Morgan, Leonard Mubalama, Paul K. N'Goran, Aaron Nicholas, Stuart Nixon, Emmanuelle Normand, Leonidas Nziguyimpa, Zacharie Nzooh-Dongmo, Richard Ofori-Amanfo, Babafemi G. Ogunjemite, Charles-Albert Petre, Hugo J. Rainey, Sebastien Regnaut, Orume Robinson, Aaron Rundus, Crickette M. Sanz, David Tiku Okon, Angelique Todd, Ymke Warren, Volker Somme

Quantifying the ecological impact of the straw-coloured fruit bat (Eidolon helvum) in West Africa

Ecosystems worldwide provide beneficial services to humans and other life-forms. Fruit-eating and flower-visiting animals play a particularly important role in the regeneration of numerous plant species through their dispersal of pollen and seeds, thereby ensuring the maintenance or restoration of these ecosystems especially in tropical Africa. However, the ability of ecosystems to function effectively and to provide these services is being compromised by many factors, including defaunation, such as through bushmeat, trophy and pet utilization; and habitat degradation, fragmentation and loss. Therefore, animals capable of long-distance seed dispersal are particularly important in fragmented landscapes for maintaining gene flow and colonizing new sites for plants. Volant seed dispersers such as birds and fruit bats capable of utilizing fragmented landscapes are thus receiving increasing attention to quantify their seed disperser services. However, many seed dispersers that eat fleshy fruit do not cover large distances and/or leave the forest cover; even those that do usually drop most seeds under the source tree, or quickly defecate ingested seeds after feeding. Thus, animal vectors, such as the straw-coloured fruit bat (Eidolon helvum), that are capable of covering large distances and retaining seeds for long periods are particularly important for maintaining connectivity among plant populations in fragmented landscapes. I expected that the seasonal migration of E. helvum over vast distances across the African continent, probably following seasonal bursts of resource availability, would cause enormous fluctuations in population size, which in turn may influence the bats' impact on local ecosystems. I used a combination of state-of-the-art GPS/acceleration loggers and concurrent monitoring of the seasonal fluctuations in colony size, phenology of bat food resources and field-based feeding experiments to collect high spatio-temporal resolution data on the eco-physiological behaviour of fruit bats under different seasonal and landscape conditions. I quantified: 1) changes in foraging movements and colony population size in response to inter-seasonal environments; 2) changes in bat colony size, activity budgeting, movement ecology and body condition responses to intra-seasonal changes in food availability; and 3) dispersal distances for seeds of bat food resources. I found that in the urban landscape in and around Accra, located in the forest ecosystem in southern Ghana, bats foraged locally (3.5 -36.7 km) and in urban areas with low tree cover during the wet season, when colony populations were low (~ 4000 individuals); major food sources during this period were fruits of introduced trees. This was in contrast to a tripling of foraging distances (24.1 - 87.9 km) during the dry season, with population peak (~ 150,000 individuals), which was not compensated for by reduced resting periods. Dry season foraging areas were random with regard to urban footprint and tree cover, and food consisted almost exclusively of nectar and pollen of native trees. Fluctuations in food abundance potentially drive a variety of eco-physiological responses in frugivorous bats, including changes in body condition, activity budgets, diets and foraging areas. In view of earlier findings that pronounced inter-seasonal changes in E. helvum movement and foraging ecology, I next expected that if there were sufficiently strong environmental factors within a single season, the bats would exhibit distinct eco-physiological responses. In a savanna ecosystem in Ouagadougou, central Burkina Faso, I concurrently investigated intra-seasonal changes in food resource availability, colony size, bat activity budget and spatio-temporal movement patterns, and bat body condition during the mono-modal wet. I found that food availability was markedly different in the early (food high) and later (food low) stages of the wet season, with different composition of dominant food species during each period. The results indicate that E. helvum opportunistically shifted diets to capitalize on different food resources as they became dominant in the landscape within the same season. Colony size correlated positively with food availability, showing a two-fold decrease with increasing food scarcity. Body condition declined significantly during food scarcity. Although bats were equally active at night in both food periods, they spent more time foraging and commuting during food low. Travel time away from day roost was lower during food high, but travel distance was similar for the two food periods. The space use in core and foraging areas did not differ in the two periods. Overall, intra-seasonal fluctuations in food resources are markedly different and apparently caused significant changes in body condition and foraging time budgets but not in distance and area use. In addition, I report for the first time the ability of E. helvum to relocate to new day roosts as solitary individuals. Individual excursions last for 1 – 6 consecutive nights before returning to the main colony during periods of food scarcity. I report for the first time that the highly gregarious, central-foraging E. helvum can spend time as solitary individuals at day roosts in foraging areas far away from colonies, apparently in response to food scarcity. Finally, I sought to translate the seasonal changes in E. helvum movements into a quantification of seed dispersal distances. By using a combination of high-resolution GPS-tracking of movements, field observations and gut retention time experiments, I modelled potential dispersal distances for small- and large-seeded fruits foraged by E. helvum during periods of colony population low (wet season) and high (dry season) in an urban and a rural landscape in the forest zone of Ghana. Nightly movements were generally longer in the urban than in the rural landscape and also longer in the dry than in the wet season. Gut passage time (mean 116 min; range 4-1143 min) was comparable to those of other fruit bats. Seed dispersal distances were similar for both large (median 42-67 m) and small (median 42-65 m) seeds, and reflected the fact that majority of seeds are dispersed only to feeding roosts through the foraging behaviour of shuttling between food trees and nearby feeding roosts. Estimated maximum seed dispersal kernel distance for small seeds was 75 km, four times further than previous maximum distance estimated for a frugivore. Furthermore, small seeds were dispersed over distances almost twice as long in the rural (49.7 km) compared to the urban (31.2 km) landscape. Maximum distances for small seeds in the urban landscape were three times longer during the dry season (75.4 km) versus the wet season (22.8 km); in contrast, distances in the rural landscape were three times longer in the wet season (67 km) compared to the dry season (24.4). For large seeds in the rural landscape, dispersal distance during the dry season (551 m) was almost twice that in the wet season (319 m). Phenology of food resources did not appear to influence seed dispersal distances. The maximum likelihood for seed dispersal beyond feeding roosts (99th percentile distance from food tree 263 m) was 4.7%. Small seeds were dispersed over even longer distances, > 500 and >1000 m, with a likelihood of 3.0 % and 2.3 % respectively. I show that E. helvum retains ingested seeds for very long periods and traverses large distances, along which both long and short-distance seed dispersal occur. This probably makes E. helvum the most important animal seed disperser currently known, at least in tropical Africa. These findings suggest that E. helvum is a keystone species for ecosystem functioning and urge its conservation. This study suggests that straw-coloured fruit bats are likely to disperse seeds in the range of hundreds of meters up to dozens of kilometres, and to pollinate trees for up to 88 km. Straw-coloured fruit bats forage over much larger distances compared to most other Old World fruit bats, thus providing vital ecosystem services across extensive landscapes. I recommend increased efforts aimed at maintaining E. helvum populations throughout Africa, since their suspected keystone role in various ecosystems is likely to increase due to the escalating loss of other seed dispersers as well as continued urbanization and habitat fragmentation. These findings provide additional evidence that (1) fruit bats may adapt their foraging movement patterns and diets within a single wet season in the savannah; similar changes were previously observed between seasons in the forest ecosystem; (2) the super-abundant production of shea and fig fruits in the savannah ecosystem may be an important factor in the annual northwards migration of E. helvum from the southern coastal forests in West Africa, thereby confirming the tight ecological inter-dependence of fruit trees and their seed dispersal via fruit bats.publishe

Protected Areas in Tropical Africa : Assessing Threats and Conservation Activities

Numerous protected areas (PAs) have been created in Africa to safeguard wildlife and other natural resources. However, significant threats from anthropogenic activities and decline of wildlife populations persist, while conservation efforts in most PAs are still minimal. We assessed the impact level of the most common threats to wildlife within PAs in tropical Africa and the relationship of conservation activities with threat impact level. We collated data on 98 PAs with tropical forest cover from 15 countries across West, Central and East Africa. For this, we assembled information about local threats as well as conservation activities from published and unpublished literature, and questionnaires sent to long-term field workers. We constructed general linear models to test the significance of specific conservation activities in relation to the threat impact level. Subsistence and commercial hunting were identified as the most common direct threats to wildlife and found to be most prevalent in West and Central Africa. Agriculture and logging represented the most common indirect threats, and were most prevalent in West Africa. We found that the long-term presence of conservation activities (such as law enforcement, research and tourism) was associated with lower threat impact levels. Our results highlight deficiencies in the management effectiveness of several PAs across tropical Africa, and conclude that PA management should invest more into conservation activities with long-term duration

Long-distance seed dispersal by straw-coloured fruit bats varies by season and landscape

On-going fragmentation of tropical forest ecosystems and associated depletion of seed dispersers threatens the long-term survival of animal-dispersed plants. These threats do not only affect biodiversity and species abundance, but ultimately ecosystem functions and services. Thus, seed dispersers such as the straw-coloured fruit bat, E. helvum, which traverse long distances across fragmented landscapes, are particularly important for maintaining genetic connectivity and colonizing new sites for plant species. Using high-resolution GPS-tracking of movements, field observations and gut retention experiments, we quantify dispersal distances for small- and large-seeded fruits foraged by E. helvum during periods of colony population low (wet season) and high (dry season) in an urban and a rural landscape in the forest zone of Ghana. Gut passage time averaged 116 min (range 4–1143 min), comparable to other fruit bats. Movements were generally longer in the urban than in the rural landscape and also longer in the dry than in the wet season. As the majority of seeds are dispersed only to feeding roosts, median dispersal distances were similar for both large (42–67 m) and small (42–65 m) seeds. However, small seeds were potentially dispersed up to 75.4 km, four times further than the previous maximum distance estimated for a similar-sized frugivore. Maximum seed dispersal distances for small seeds were almost twice as long in the rural (49.7 km) compare to the urban (31.2 km) landscape. Within the urban landscape, estimated maximum dispersal distances for small seeds were three times longer during the dry season (75.4 km) compared to the wet season (22.8 km); in contrast, distances in the rural landscape were three times longer in the wet season (67 km) compared to the dry season (24.4). Dispersal distances for large seeds during the dry season (551 m) in the rural landscape were almost twice that in the wet season (319 m). We found no influence of food phenology on dispersal distances. The maximum likelihood for seed dispersal beyond feeding roosts (mean distance from food tree 263 m) was 4.7%. Small seeds were dispersed over even longer distances, >500 and >1000 m, with a likelihood of 3.0 % and 2.3 % respectively. Our data show that E. helvum retains ingested seeds for very long periods and may traverse large distances, probably making it an important long distance seed disperser in tropical Africa. We suggest E. helvumis important for ecosystem functioning and urge its conservation.publishe

Linking colony size with quantitative estimates of ecosystem services of African fruit bats

Animal-mediated seed dispersal is a pivotal component of functioning forest ecosystems all over the globe. Animals that disperse seeds away from their parental plants increase the seeds' chances of survival by releasing them from competition and specialised predators and so contribute to maintain the biodiversity of forests. Furthermore, seeds dispersed into deforested areas provide the opportunity for reforestation. Forest regeneration especially depends on animals that cover large distances easily and cross forest gaps, in particular large-bodied frugivores or mobile species such as birds and bats. Yet, frugivores have started to disappear from forests everywhere, with potentially dramatic consequences for forest composition, regeneration and overall forest biomass. Identifying which species contribute substantially to the dispersal of viable seeds, and how these services are affected by fluctuations in population size, is thus pivotal to the understanding and conservation of forest ecosystems.publishe

Overall Dynamic Body Acceleration in Straw-Colored Fruit Bats Increases in Headwinds but Not With Airspeed

Atmospheric conditions impact how animals use the aerosphere, and birds and bats should modify their flight to minimize energetic expenditure relative to changing wind conditions. To investigate how free-ranging straw-colored fruit bats (Eidolon helvum) fly with changing wind support, we use data collected from bats fit with GPS loggers and an integrated triaxial accelerometer and measure flight speeds, wingbeat frequency, and overall dynamic body acceleration (ODBA) as an estimate for energetic expenditure. We predicted that if ODBA reflects energetic expenditure, then we should find a curvilinear relationship between ODBA and airspeed consistent with aerodynamic theory. We expected that bats would lower their airspeed with tailwind support and that ODBA will decrease with increasing tailwinds and increase with wingbeat frequency. We found that wingbeat frequency has the strongest positive relationship with ODBA. There was a small, but negative, relationship between airspeed and ODBA, and bats decreased ODBA with increasing tailwind. Bats flew at ground speeds of 9.6 ± 2.4 ms−1 (Mean ± SD, range: 4.3–23.9 ms−1) and airspeeds of 10.2 ± 2.5 ms−1, and did not modify their wingbeat frequency with speed. Free-ranging straw-colored fruit bats therefore exerted more total ODBA in headwinds but not when they changed their airspeed. It is possible that the flexibility in wingbeat kinematics may make flight of free-ranging bats less costly than currently predicted or alternatively that the combination of ODBA and airspeed at our scales of measurement does not reflect this relationship in straw-colored fruit bats. Further work is needed to understand the full potential of free-ranging bat flight and how well bio-logging techniques reflect the costs of bat flight.publishe

Tilan vaikutus luovuuteen innovoinnissa

In the OVET project we study, how space affects users’ creativity during innovation activity. The space covers physical, virtual and social aspects, including communication technology, usage of a space and people’s behaviour in a space. The core of the project is to develop a model and methods for evaluating space experience and creativity from user-centred point of view. The impact of space on creativity is studied by simulating innovation activity in different space combinations.OVET-projektissa tutkitaan tilan vaikutusta käyttäjien luovuuteen innovaatiotoiminnassa. Tutkimuksessa tarkastellaan tilaa laajasta näkökulmasta, jossa otetaan huomioon paitsi fyysinen tila myös viestintäteknologian hyödyntäminen tilassa ja tilan sosiaalinen ulottuvuus, kuten ihmisten käyttäytyminen ja vuorovaikutus tilassa. Projektissa kehitetään menetelmä käyttäjien tilakokemuksen ja luovuuden arvioimiseen. Tilan vaikutusta käyttäjän luovuuteen tutkitaan simuloimalla innovaatiotoimintaa erilaisissa tilaratkaisuissa

GPS tracks of <i>E</i>. <i>helvum</i> from wet (a) and dry season (b).

<p>Round dots represent commuting and roosting locations, and octagons foraging locations of <i>E</i>. <i>helvum</i>. Black circles indicate the maximum foraging distance of wet season (37 km) and dry season (88 km). Southern part of map corresponds to Atlantic Ocean. See Supporting Information (<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0138985#pone.0138985.s004" target="_blank">S3 Fig</a>) for detailed maps of foraging areas of selected individuals.</p