69 research outputs found
Carnivorous <i>Nepenthes</i> pitcher plants are a rich food source for a diverse vertebrate community
No full textCarnivorous pitcher plants capture insect prey to acquire essential nutrients while growing on extremely poor soils. A few individual species have evolved mutualistic relationships with small mammals that visit the traps to harvest nectar, and in return leave faecal droppings in the pitchers. Here we report that a diverse guild of nectar-harvesting vertebrates visits pitchers of two common lowland Nepenthes species without providing any obvious benefit for the plants. Over four consecutive field seasons, we observed four species of sunbirds and one species of tree shrew drinking nectar from pitcher plants. Foraging activity was highest in the morning and late afternoon. Van Hasselt’s, Brown-throated and olive-backed sunbirds were regular and highly abundant pitcher visitors in two different field sites. A crimson sunbird and a lesser tree shrew were each observed harvesting nectar on one occasion. The vertebrates harvested nectar from the pitcher rim (peristome) of N. rafflesiana and from the underside of the pitcher lid of N. gracilis. A comparison of the nectar production of these and three further sympatric species revealed exceptionally high quantities of nectar for N. rafflesiana. Other factors such as plant and pitcher abundance and the habitat preferences of the observed vertebrates are likely to also play a role in their choice to visit particular species. This is the first account of a case of obvious nectar robbing from Nepenthes pitchers by a guild of species that are too large to serve as prey, while the pitcher size and shape prevent faecal droppings from reaching the pitcher’s inside. This interaction provides an example of a possible starting point for the evolution of the elaborate mutualistic relationships observed in some species. Follow-up adaptations of pitcher shape could enable the plants to catch the droppings of their visitors and turn an exploitative relationship into a mutualism
Figure 7 in Carnivorous Nepenthes pitcher plants are a rich food source for a diverse vertebrate community
No full textFigure 7. Large nectar droplets (arrow) regularly accumulate on the lower lid surface of Nepenthes gracilis pitchers early in the morning.Published as part of <i>Bauer, Ulrike, Rembold, Katja & Grafe, T. Ulmar, 2015, Carnivorous Nepenthes pitcher plants are a rich food source for a diverse vertebrate community, pp. 483-495 in Journal of Natural History 50</i> on page 491, DOI: 10.1080/00222933.2015.1059963, <a href="http://zenodo.org/record/3985530">http://zenodo.org/record/3985530</a>
Research article
No full textBackground: In many species of birds, pair bonded males and females precisely co-ordinate their vocalisations to form duets. Duetting behaviour, although still somewhat of an enigma, is thought to function primarily in territorial defence and mate guarding. We identify an additional function of duetting in an afrotropical bird, the tropical boubou (Laniarius aethiopicus), that uses one duet type as a postconflict display probably to advertise victory to other boubous. Results: We simulated intrusions into boubou territories in the field in Ivory Coast, West Africa using playbacks of four different types of boubou duets to test the use of the presumptive acoustic victory display before, during and after playbacks. These staged encounters resulted in either retreat of the focal birds during playback or continued presence accompanied by vocal displays after playback had ceased. Losers of encounters never sung after retreating whereas 11 out of 18 pairs sung the presumptive victory duet after the encounter. Analysis revealed that the presumptive victory display was sung significantly more often after than before or during the playback treatment
Figure 3 in Prolonged parental behaviour by males of Limnonectes palavanensis (Boulenger 1894), a frog with possible sex-role reversal
No full textFigure 3. Embryonic development of the eggs of L. palavanensis. (a) The vegetal pole differentiates from the animal pole 24 h after fertilisation. (b) Neural folds develop, Gosner stage 15 (3 days old). (c) The head forms and the tail elongates around the yolk sac, Gosner stages 18–19 (4 days old). (d) Eyes become apparent and external gills are visible, Gosner stages 21–22 (6 days old). (e) The tadpoles are now sensitive to light, the eyes are completely formed and the gills are not visible anymore, Gosner stages 24–25 (9 days old). (f) The tadpoles are ready to hatch (10 days old).Published as part of Goyes Vallejos, Johana, Grafe, T. Ulmar & Wells, Kentwood D., 2018, Prolonged parental behaviour by males of Limnonectes palavanensis (Boulenger 1894), a frog with possible sex-role reversal, pp. 2473-2485 in Journal of Natural History 52 (37-38) on page 2479, DOI: 10.1080/00222933.2018.1539196, http://zenodo.org/record/517766
Figure 4 in Prolonged parental behaviour by males of Limnonectes palavanensis (Boulenger 1894), a frog with possible sex-role reversal
No full textFigure 4. Climbing behaviour of the tadpoles of L. palavanensis. (a) The male stimulates hatching by touching the eggs with its chin and fingers. (b) The male positions himself on top of the eggs and twitches his abdomen and fingers. (c) He steps on the eggs, breaking the egg capsule and separating them. (d) The first tadpole starts climbing (indicated by the arrow). The male sits on top of the now free tadpoles and waits for them to climb. (e) The male starts to turn around while the tadpoles wriggle onto his back. After every turn he remains still for a few seconds while the tadpoles climb. (f) The tadpoles move around and rearrange themselves while the last tadpole makes it to the top.Published as part of Goyes Vallejos, Johana, Grafe, T. Ulmar & Wells, Kentwood D., 2018, Prolonged parental behaviour by males of Limnonectes palavanensis (Boulenger 1894), a frog with possible sex-role reversal, pp. 2473-2485 in Journal of Natural History 52 (37-38) on page 2480, DOI: 10.1080/00222933.2018.1539196, http://zenodo.org/record/517766
Supplementary feeding affects the breeding behaviour of male European treefrogs (<it>Hyla arborea</it>)
No full textAbstract Background We investigated the effects of energetic constraints on the breeding behaviour of male European treefrogs Hyla arborea and how calling males allocated additional energy supplied by feeding experiments. Results Presence in the chorus was energetically costly indicated by both fed and unfed males losing weight. Males that were supplied with additional energy did not show longer chorus tenure. Instead, fed males returned sooner to the chorus. Additionally, fed males called more often than control males, a novel response for anurans. A significantly higher calling rate was noted from males even 31 nights after supplementary feeding. Conclusion This strategy of allocating additional energy reserves to increasing calling rate is beneficial given the preference of female hylids for males calling at high rates and a female's ability to detect small incremental increases in calling rate.</p
Conservation Status of the Amphibians of Brunei Darussalam
No full textBrunei Darussalam is located on the northern coast of the island of Borneo and has a total land area of 5766
km2 . It is divided into two disjunct regions: the districts of Brunei/Muara, Tutong, and Belait in the west and Temburong in the east (Fig. 1). The two parts are completely surrounded and separated by the Malaysian state of Sarawak. The major forest types in Brunei are (1) lowland mixed-dipterocarp rainforests, (2) peatswamp forests, (3) heath forests (Kerangas), and (4) mangrove forests (Ashton et al. 2003)
Evidence for alternative trapping strategies in two forms of the pitcher plant, <i>Nepenthes rafflesiana</i>
No full textNepenthes pitchers are specialized leaves that function as insect traps. Several pitcher components may contribute to trapping, including the pitcher fluid, slippery wax crystals and downward-pointing epidermal cells on the inner pitcher wall, and the wetness-dependent pitcher rim (peristome), but the relative importance of these traits is unclear. Mechanisms of prey capture and retention in the field were investigated by quantifying the effect of 'knock-out' manipulations of individual pitcher structures, and by testing the ability of pitcher fluids and water to retain insects. Two forms of Nepenthes rafflesiana Jack ('elongate' and 'typical') with contrasting combinations of pitcher traits were compared. Wax crystals on the inner pitcher wall were found to be the most important trapping structure in the elongate form, whereas the typical form relied primarily on the peristome. The pitcher fluids of both forms, differing markedly in the degree of viscoelasticity, retained significantly more ants than water. The present results show that pitcher plants utilize several mechanisms for prey capture and retention, varying in efficiency and relative importance between forms. It is proposed that these differences represent alternative prey capture strategies that may provide a mechanism to reduce competition and facilitate species co-existence in nutrient-limited habitats
Temporal variation in acoustic and visual signalling as a function of stream background noise in the Bornean foot-flagging frog, Staurois parvus
No full textHigh background noise can interfere with signal detection and perception. Bornean foot-flagging frogs,Staurois parvus, live along noisy streams and use both acoustic and visual signals to communicate. It remains unclear why acoustic signalling is retained given that visual signalling appears to have clear advantages under these noisy conditions. We hypothesized that temporal dynamics in stream noise have shaped the multimodal communication system inS. parvuswith acoustic signalling at an advantage under more quiet conditions, whereas visual signals will prevail when the noise of rushing water is high after rains. We found that as predicted, maleS. parvusincreased foot flagging and decreased advertisement calling when presented with playbacks of stream noise compared to less noisy pre-playback conditions. Such context-dependent dynamic-selection regimes are recently gaining wider attention and enhance our understanding of the flexibility seen in the use of multimodal signals inS. parvus.</jats:p
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