Browsing by Author "Fyumagwa, Robert"

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    A dead giveaway: foraging vultures and other avian scavengers respond to auditory cues
    (John Wiley & Sons, 2020) Jackson, Craig R.; Maddox, Thomas; Mbise, Franco P.; Stokke, Bård G.; Belant, Jerrold L.; Bevanger, Kjetil; Durant, Sarah M.; Fyumagwa, Robert; Ranke, Peter S.; Røskaft, Eivin; May, Roel; Fossøy, Frode
    Carrion represents an unpredictable and widely distributed primary food source for vultures and other avian scavengers. Avian scavengers in African savanna ecosystems are reported to rely exclusively on visual stimuli to locate carcasses. However, carnivores’ predation of large mammalian herbivores and subsequent competition for access to the carcass can result in considerable noise, often audible over long distances and for prolonged periods. Vultures and other avian scavengers may therefore detect and respond to these auditory cues, as do the mammalian carnivores alongside which vultures have coevolved, but this has not been investigated to date. Working in the Serengeti ecosystem, Tanzania, we used diurnal auditory broadcasts to simulate predation and competitive carnivore feeding interactions. Based on the current understanding of avian scavenger ecology, we hypothesized that avian responses to call‐in stations would be evoked exclusively by visual, rather than auditory, cues. We therefore predicted that (a) the arrival of avian scavengers at call‐in stations should be preceded and facilitated by mammalian carnivores and that (b) the arrival of avian scavengers would be positively correlated with the number of mammalian scavengers present, which would increase detectability. We recorded 482 birds during 122 separate playback events. In 22% of these instances, avian scavengers arrived first, ruling out responses based exclusively on visual observations of mammalian carnivores, thereby contradicting our first prediction. Furthermore, the first avian arrivals at survey sessions were inversely related to the number of hyenas and jackals present, contradicting our second prediction. Since no bait or carcasses were used during the experiments, these responses are indicative of the birds’ ability to detect and respond to audio stimuli. Our findings challenge the current consensus of sensory perception and foraging in these species and provide evidence that avian scavengers have the ability to use sound to locate food resources.
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    Do carnivore surveys match reports of carnivore presence by pastoralists? a case of the eastern Serengeti ecosystem
    (2020) Mbise, Franco P.; Jackson, Craig R.; Lyamuya, Richard; Fyumagwa, Robert; Ranke, Peter S.; Røskaft, Eivin
    Human-carnivore encounters are common where humans and wild carnivores share the same landscape. The frequency of such encounters gives insight regarding carnivore density and might correlate with human-carnivore conflict incidences. We interviewed livestock owners in the eastern Serengeti ecosystem and recorded reported carnivore presence and relative abundance. We simultaneously conducted a carnivore survey to assess the potential variability of reported carnivore presence that was recorded during the surveys. The playback surveys attracted 9 lions (Panthera leo), 88 spotted hyenas (Crocuta crocuta) and 47 black-backed jackals (Canis mesomelas schmidti) to 12 call-in stations which were resurveyed three times (36 playbacks in total). Reported encounters with lions, leopards (Panthera pardus), cheetahs (Acinonyx jubatus), spotted hyenas, African wild dogs (Lycaon pictus) and jackals were higher closer to the Serengeti National Park (SNP). Data from carnivore surveys were positively correlated with what people reported in questionnaires. These results indicate that local reports of encounters with wild carnivores may act as an important indicator of carnivore presence. Combining observational data through surveys with data reported by local people in areas where humans and wild carnivores coexist may improve existing data on carnivore abundance and distribution in such areas.
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    Human habituation reduces hyrax flight initiation distance in Serengeti
    (John Wiley & Sons, Inc., 2019) Mbise, Franco P.; Fredriksen, Kari-Elise; Ranke, Peter S.; Jackson, Craig; Fyumagwa, Robert; Holmern, Tomas; Fossøy, Frode; Røskaft, Eivin
    Many animal populations are exposed to disturbance originating from human ac‐ tivities. In response to human disturbance, certain animals display a variety of po‐ tentially costly behavioural responses, such as increased antipredator behaviour or relocation to new areas. In contrast, other animals seemingly thrive in the presence of humans and benefit from human‐derived resources. Flight initiation distance (FID: the distance between predator and prey when prey starts to flee) is a measure com‐ monly used to assess animals’ tolerance to humans. In this study, we tested how FID changes in relation to human presence in two hyrax species in Serengeti National Park. Hyraxes living on kopjes (rock outcrops) among human settlements showed a significantly shorter FID than hyraxes living on kopjes without human settlements. In addition, we found that hyraxes feeding before the experiment had shorter FID than hyraxes resting or being vigilant, and hyraxes disturbed during the early morn‐ ing had shorter FID than hyraxes disturbed during late morning. We did not find any significant effects of group size or species composition on FID. Our results suggest that hyraxes living in the presence of humans are habituated and are not adversely affected by human settlements