Aspects of the behaviour of African giant pouched rats (Cricetomys sp. nov) which impacts seed dispersal of large- seeded tree species in a West African montane forest landscape. A thesis submitted in partial fulfilment of the requirements for the Degree of Doctor of philosophy in Ecology at the University of Canterbury Biplang G. Yadok University of Canterbury Christchurch, New Zealand 2018 Table of Contents Table of Contents ....................................................................................................................... ii List of Tables ........................................................................................................................... viii List of Figures ............................................................................................................................. x Acknowledgements .................................................................................................................. xv Abstract ..................................................................................................................................xviii Chapter 1: Background, scatterhoarding, small mammals and seed dispersal ........................ 1 1.1 Introduction................................................................................................................. 1 1.2 Food hoarding ............................................................................................................. 1 1.2.1 Ecology of tropical scatterhoarding rodents ....................................................... 3 1.2.2 Scatterhoarding rodents and seed dispersal ....................................................... 4 1.2.3 Factors influencing scatterhoarding behaviour in rodents ................................. 6 1.2.4 Habitats of tropical scatterhoarding rodents ...................................................... 8 1.2.5 Scatterhoarding rodents in Africa ...................................................................... 10 1.3 African Giant Pouched rats Cricetomys spp .............................................................. 11 1.4 Seed dispersal in the study area - Ngel Nyaki forest ................................................ 13 1.5 Aim and research questions ...................................................................................... 15 1.6 References ................................................................................................................. 16 Chapter 2: Population dynamics and activity patterns of the African giant pouched rat Cricetomys sp nov. in Ngel Nyaki Forest Reserve .................................................................... 21 2.1 Introduction............................................................................................................... 22 2.1.1 Population density of forest mammals.............................................................. 22 2.1.2 Demographics of small mammals ...................................................................... 23 2.1.3 Methods for sampling small mammals.............................................................. 26 2.1.4 Population dynamics of small mammals in the tropics ..................................... 28 2.1.5 Distribution of African giant pouched rats. ....................................................... 28 ii 2.1.6 Hypotheses ........................................................... Error! Bookmark not defined. 2.2 Methods .................................................................................................................... 30 2.2.1 Live-trapping ...................................................................................................... 31 2.2.2 Camera trapping ................................................................................................ 32 2.2.3 Statistical Analyses ............................................................................................. 33 2.3 Results ....................................................................................................................... 35 2.4 Discussion .................................................................................................................. 46 2.4.1 Microhabitats with burrows and the presence of Cricetomys .......................... 47 2.4.2 Cricetomys morphometrics ................................................................................ 47 2.4.3 Distribution of Cricetomys in NNFR ................................................................... 48 2.4.4 Uneven density of Cricetomys in the forest core .............................................. 49 2.4.5 Uneven densities of male and female Cricetomys ............................................ 51 2.4.6 Spatial movement of Cricetomys ....................................................................... 52 2.4.7 Cricetomys activity pattern ................................................................................ 52 2.5 Conclusion ................................................................................................................. 53 2.5 References ..................................................................................................................... 53 Chapter 3: Effect of food availability on the abundance of African giant pouched rat (Cricetomys sp. nov.) in Ngel Nyaki Forest Reserve ................................................................. 62 3.1 Introduction............................................................................................................... 62 3.1.1 Food availability and the density of small mammals......................................... 64 3.1.2 Distribution of tropical scatterhoarding rodents and their associated food items 65 3.1.3 Distribution of Afrotropical scatterhoarding rodents........................................ 66 3.1.4 Hypotheses ........................................................... Error! Bookmark not defined. 3.2 Methods .................................................................................................................... 68 3.2.1 Large plots .......................................................................................................... 69 iii 3.2.2 Camera trapping and burrow survey ................................................................. 70 3.2.3 Small plots .......................................................................................................... 71 3.2.4 Statistical analyses ............................................................................................. 71 3.3 Results ....................................................................................................................... 72 3.3.1 Density of Cricetomys in large plots .................................................................. 72 3.3.2 Density of Cricetomys burrows in small plots. ................................................... 74 3.4 Discussion .................................................................................................................. 77 3.4.1 Cricetomys abundance and distribution of trees .............................................. 77 3.4.2 Density of Cricetomys burrows and distribution of trees .................................. 79 3.4.3 Implications for seed dispersal .......................................................................... 81 3.4.4 Conclusion .......................................................................................................... 81 3.5 References ................................................................................................................. 82 Chapter 4: Effect of predation risk on microhabitat use by African giant pouched rats (Cricetomys sp. nov) ................................................................................................................. 85 4.1 Introduction............................................................................................................... 86 4.1.1 Predation risk and vegetation structure ............................................................ 87 4.1.2 Measuring predation risk ........................................................................................ 88 4.1.3 Predation risk in small mammals ............................................................................ 90 4.1.4 Predation risk, microhabitat use and seed dispersal by African giant pouched rats .......................................................................................................................................... 92 4.1.2 Hypotheses ........................................................... Error! Bookmark not defined. 4.2 Methods .................................................................................................................... 93 4.2.1 Study site. ........................................................................................................... 94 4.2.2 GUD experiment ................................................................................................ 94 4.2.3 Spool and line experiment ................................................................................. 96 4.2.4 Statistical analyses ............................................................................................. 98 iv 4.3 Results ....................................................................................................................... 99 4.3.1 GUD and predation risk ....................................................................................