Breeding phenology and population dynamics of the endangered Forest Spiny Reed Frog Afrixalus sylvaticus Schiøtz, 1974 in Shimba Hills, Kenya
Main Article Content
Abstract
Afrixalus sylvaticus Schiøtz, 1974 is a species of hyperoliid frog inhabiting coastal forest Kenya. It is classified as endangered under IUCN B2ab(iii) ver 3.1 and occurs in the Shimba Hills National Park and hinterlands. Habitat loss and other human activities are threatening the species. Therefore, understanding the breeding ecology and population dynamics is important for its conservation. This study assessed the breeding ecology and population dynamics of the species in the protected and community landscapes in Shimba Hills National Reserve in Kenya. Data was collected through ecological surveys conducted from June 2016 to July 2017 using a visual encounter surveys (VES) method. The results show that the species was more abundant during the wet season than dry (58% and 42%, respectively). The population estimate was 192 individuals and a density of 0.98 individuals/km2. Regarding the morphology, the mean snout-vent length (SVL) for males was 15.12 mm and females 15.96 mm, but there was no significant difference (t-test = 0.87, p = 0.390, df = 39). The mean weight of both gravid and non-gravid females was 6.05 g and males was 4.82 g. The weights were statistically different between both sexes (t-test = 3.50, p-value = 0.001, df = 39). The sex ratio was 1:2 (male: female). There was more activity in the wet season (April and May), and the breeding habitats were reeds and water lilies. The threats identified to their habitat include; human activities such as bush burning, livestock grazing, drainage, and plantation of exotic tree species (Eucalyptus sp.) that have led to habitat loss and degradation. The study recommends that the reforestation processes such as plantation of exotic species such as Eucalyptus sp. and Casuarina sp. and bush burning in the wetlands and species habitats must be discouraged among the stakeholders (community and park management). Moreover, more synchronized studies are necessary to highlight the driver(s) of imbalanced sex ratios and species habitat shifts.
Article Details
This work is licensed under a Creative Commons Attribution 4.0 International License.
Authors own the copyright to the articles published in JoTT. This is indicated explicitly in each publication. The authors grant permission to the publisher Wildlife Information Liaison Development (WILD) Society to publish the article in the Journal of Threatened Taxa. The authors recognize WILD as the original publisher, and to sell hard copies of the Journal and article to any buyer. JoTT is registered under the Creative Commons Attribution 4.0 International License (CC BY), which allows authors to retain copyright ownership. Under this license the authors allow anyone to download, cite, use the data, modify, reprint, copy and distribute provided the authors and source of publication are credited through appropriate citations (e.g., Son et al. (2016). Bats (Mammalia: Chiroptera) of the southeastern Truong Son Mountains, Quang Ngai Province, Vietnam. Journal of Threatened Taxa 8(7): 8953–8969. https://doi.org/10.11609/jott.2785.8.7.8953-8969). Users of the data do not require specific permission from the authors or the publisher.
References
Beebee, T.J. & R.A. Griffiths (2005). The amphibian decline crisis: A watershed for conservation biology? Biological Conservation 125(3): 271–285. https://doi.org/10.1016/j.biocon.2005.04.009
Blaustein, A.R., S.C. Walls, B.A. Bancroft, J.J. Lawler, C.L. Searle & S.S. Gervasi (2010). Direct and indirect effects of climate change on amphibian populations. Diversity 2(2): 281–313. https://doi.org/10.3390/d2020281
Burrowes, P.A., R.L. Joglar & D.E. Green (2004). Potential causes for amphibian declines in Puerto Rico. Herpetologica 60(2): 141–154. https://doi.org/10.1655/03-50
Bwong, B.A., J.O. Nyamache, P.K. Malonza, D.V. Wasonga, J.M. Ngwava, C.D. Barratt, P. Nagel & S.P. Loader (2017). Amphibian diversity in Shimba Hills National Reserve, Kenya: A comprehensive list of specimens and species. Journal of East African Natural History 106(1): 19–46. https://doi.org/10.2982/028.106.0104
Crump, M.L. & N.J. Scott (1994). Visual encounter survey, pp. 84–92. In: Heyer, R., M.A. Donnelly, M. Foster & R. Mcdiarmid (eds.). Measuring and Monitoring Biological Diversity—Standard Methods for Amphibians. Smithsonian Institution, USA, 320 pp.
Donnelly, M., G. Craig, J. Juterbock & A. Ross (1994). Techniques for marking amphibians, pp. 277–283. In: Heyer, W.R., M.A. Donnelly, R.W. Mcdiarmid, L.C. Hayek & M.S. Foster (ed.). Measuring and Monitoring Biological Diversity: Standard Methods for Amphibians. Smithsonian Institution Press, 383 pp.
Frost, D. (2011). Amphibian species of the world: An online reference. American Museum of Natural History, New York, USA. Version 5.5.
Gallant, A.L., R.W. Klaver, G.S. Casper & M.J. Lannoo (2007). Global rates of habitat loss and implications for amphibian conservation. Copeia 2007(4): 967–979. https://doi.org/10.1643/0045-8511(2007)7[967:GROHLA]2.0.CO;2
Gardner, T.A., J. Barlow & C.A. Peres (2007). Paradox, presumption, and pitfalls in conservation biology: The importance of habitat change for amphibians and reptiles. Biological Conservation 138(1–2): 166–179. https://doi.org/10.1016/j.biocon.2007.04.017
Grant, E.H.C., D.A. Miller & E. Muths (2020). A synthesis of evidence of drivers of amphibian declines. Herpetologica 76(2): 101–107. https://doi.org/10.1655/0018-0831-76.2.101
Hamer, A.J. & K.M. Parris (2011). Local and landscape determinants of amphibian communities in urban ponds. Ecological Applications 21(2): 378–390. https://doi.org/10.1890/10-0390.1
Houlahan, J.E., C.S. Findlay, B.R. Schmidt, A.H. Meyer & S.L. Kuzmin (2000). Quantitative evidence for global amphibian population declines. Nature 404(6779): 752.
IUCN SSC Amphibian Specialist Group (2016). Afrixalus sylvaticus. The IUCN Red List of Threatened Species 2016: e.T56080A84396971. https://doi.org/10.2305/IUCN.UK.2016-1.RLTS.T56080A84396971.en. Accessed on 12 May 2022.
Malonza, P.K., D.M. Mulwa, J.O. Nyamache & G. Jones (2018). Biogeography of the Shimba Hills ecosystem herpetofauna in Kenya. Zoological Research 39(2): 97. https://doi.org/10.24272%2Fj.issn.2095-8137.2017.048
Martin, P., P. Schiøtz & H. Kim (2004). Afrixalus sylvaticus. The IUCN Red List of Threatened Species 2004. https://doi.org/10.1371/journal.pone.0187283
Peek, R.A., S.M. Yarnell & A.J. Lind (2017). Visual Encounter Survey Protocol for Rana Boylii in Lotic Environments. Center for Watershed Sciences, John Muir Institute of the Environment, University of California, Davis, CA, USA.
Pickersgill, M. (1984). Three new Afrixalus (Anura: Hyperoliidae) from south-eastern Africa. Durban Museum Novitates 13(17): 203–220.
Pickersgill, M. (2005). The taxonomy and ethology of the Afrixalus stuhlmanni complex (Anura: Hyperoliidae). Steenstrupia 29(1): 1–38.
Schiøtz, A. (1999). Treefrogs of Africa. Chimaira, Frankfurt am Main, 350 pp.
Schmidt, B.R., M. Schaub & B.R. Anholt (2002). Why you should use capture-recapture methods when estimating survival and breeding probabilities: On bias, temporary emigration, over dispersion, and common toads. Amphibia-Reptilia 23: 375–388.
Shine, R. (1979). Sexual selection and sexual dimorphism in the Amphibia. Copeia 1979(2): 297–306. https://doi.org/10.2307/1443418
Spawls, S., R.C. Drewes & D.V. Wasonga (2019). The amphibians of Kenya. Stephen Spawls, 56 pp. https://doc.rero.ch/record/328050/files/Amphibians_of_Kenya_Book_August_2019_Downloadable_Version.pdf.
Stuart, S.N., J.S. Chanson, N.A. Cox, B.E. Young, A.S. Rodrigues, D.L. Fischman & R.W. Waller (2004). Status and trends of amphibian declines and extinctions worldwide. Science 306(5702): 1783–1786. https://doi.org/10.1126/science.1103538
Tillack, F., R. de Ruiter & M.O. Rödel (2021). A type catalogue of the reed frogs (Amphibia, Anura, Hyperoliidae) in the collection of the Museum für Naturkunde Berlin (ZMB) with comments on historical collectors and expeditions. Zoosystematics and Evolution 97: 407.
Valencia-Aguilar, A., A.M. Cortés-Gómez & C.A. Ruiz-Agudelo (2013). Ecosystem services provided by amphibians and reptiles in Neotropical ecosystems. International Journal of Biodiversity Science, Ecosystem Services & Management 9(3): 257–272.
Vitt, L.J., T.C. Avila‐Pires, J.P. Caldwell & V.R. Oliveira (1998). The impact of individual tree harvesting on thermal environments of lizards in Amazonian rain forest. Conservation Biology 12(3): 654–664. https://doi.org/10.1111/j.1523-1739.1998.96407.x
Wake, D.B. (1991). Declining amphibian populations. Science 253(5022): 860–861. https://doi.org/10.1126/science.253.5022.860
Walls, S.C., L.C. Ball, W.J. Barichivich, C.K. Dodd, K.M. Enge, T.A. Gorman, K.M. O’Donnell, J.G. Palis & R.D. Semlitsch (2017). Overcoming challenges to the recovery of declining amphibian populations in the United States. Bioscience 67(2): 156–165. https://doi.org/10.1093/biosci/biw153
Yildiz, M.Z. & B. Göcmen (2012). Population dynamics, reproduction, and life history traits of Taurus Frog, Rana holtzi Werner, 1898 (Anura: Ranidae) in Karagöl (Ulukışla, Niğde), Turkey. Herpetologica Romanica 6: 1–40.