Ecology and population dynamics of small mammals in the Ankazomivady Forest, Madagascar

Voahangy Soarimalala

Association Vahatra CRVOI Introduction

• Madagascar: rich in endemic small mammal, 92% occuring species, but little known about their zoonoses,

• The exception is plague transmitted by introduced species, Rattus rattus and R. norvegicus,

• Plague results in human epidemics and could contributed to the decline of endemic rodents. Endemic small mammals

Tenrecidae 32 species

Microgale dobsoni Hemicentetes nigriceps

Nesomyinae Rodentia 27 species

Eliurus minor Nesomys rufus Introduced small mammals

Rattus rattus Suncus murinus Rodentia Soricomorpha High abundance of Transmission cycles of Rattus rattus in human various potential diseases disturbed forest areas to endemic species and at a range of human populations living elevations. near the forest area. Objectives

Environmental contamination by other pathogens probably responsible for human and endemic mammal infections. CRVOI and Vahatra Association conducting inventory of small mammals :

1. To increase available information,

2. Provide biological samples for pathogen detection and identifying infectious agents,

3. Evaluation of the possible pathogen transmission routes between endemic and introduced small mammals. Study site

• Ankazomivady, Ambositra

• 1670 m

• Central Highlands humid montane forest

• Degraded, fragmented and isolated from other forest blocks Methods • Trapping sessions:  December 2010  November 2011  March 2012

• Traps:

 80 Shermans and

20 National traps x Sherman National 6 nights

 3 lines of pit-fall x 6 nights

• Collection of ectoparasites, muscle for molecular studies and organs for Pit-fall Laboratory pathogen research Species richness

S1 S2 S3 S4 S5 S6 S7 S8

Elevation (m) 1625 1575 1500 1550 1500 1500 1670 1600 Tenrecidae 9 7 9 11 11 9 12 10 endemic Rodentia 7 6 5 1 1 7 1 6 endemic Total Rodentia 8 6 6 2 2 8 2 6 Total endemic small 16 13 14 12 12 16 13 16 mammals Total small 17 13 15 13 14 17 14 16 mammals

S1 : Andringitra, S2 : Ivohibe, S3 : Andohahela, S4 : Tsinjoarivo, S5 : Ambohitantely, S6 : Fandriana-Marolambo, S7 : Ankazomivady, S8 : Manambolo Individuals captured

Species December 2010 November 2011 March 2012 Microgale cowani 21 25 35 Microgale dobsoni 7 8 32 Tenrec ecaudatus 0 5 0 Microgale gymnorhyncha 0 1 3 Oryzorictes hova 9 0 0 Microgale longicaudata 4 1 2 Microgale majori 3 3 0 Hemicentetes nigriceps 4 4 0 Microgale parvula 8 1 0 Microgale principula 1 2 0 Microgale cf. taiva 1 1 0 Setifer setosus 0 1 1 Eliurus minor 14 78 62 Rattus rattus 11 26 70 Total 83 156 205 Species that tested positive for Paramyxoviruses 90 80 70 60 50 40 December 2010 30 November 2011 20 March 2012 10 0 Species that tested positive for Paramyxoviruses

Species Tested Total number positive individual Eliurus minor 11 109 Rattus rattus 1 10 Microgale cowani 34 73 Microgale dobsoni 19 44 Microgale gymnorhyncha 2 3 Microgale longicaudata 1 7 Microgale majori 2 6 Microgale principula 2 3 Microgale taiva 1 1 Population dynamics of Eliurus minor

90 Inventory of others 80 forests cover at

70 same elevation in

60 Ankazomivady forest and using 50 same trapping 40 methodology 30 20 10

0 3 to 12 individuals of January December November March 1998 2010 2011 2012 Eliurus minor Shifts in abundance of Eliurus minor

• E. minor appears to be adapted to forest habitat disturbance, at least on the short and middle-term,

• Slight decrease between November 2011 and March 2012 may be best explained by population cycling or food availability,

• Different biotic and abiotic factors acting in unison, might explain the notable shift starting in December 2010, Shifts in abundance of Eliurus minor

• Shrinkage of forest cover due to anthropogenic disturbance could stimulate small mammal population sinks in remaining forested areas,

• Data from Central higlands of Madagascar confirm when R. rattus colonized naturals habitats, distinct reduction density and diversity of native rodents,

• During the last two sessions, E. minor and R. rattus occurred in strict syntopy and in high densities. High abundance on Microgale cowani and M. dobsoni

• Not surprising, amongst Microgale spp. these two species are able to adapt to disturbed and degraded habitats, at least on the short and medium-term,

• Results of studies in fragmented and isolated forests of Ambohitantely colonized by R. rattus or S. murinus show no clear impact on Microgale spp. Conclusion

• Paramyxoviruses detected in Ankazomivady. Question is if it is pathogenic or not to the native and introduced small mammals? • Given its detection since 2010, it can be presumed not to be virulent, particularly in light of population expansion of certain endemic small mammals in two different groups. • Recommendation: continued monitoring of small mammals at the site and if: A) detection rate increases and mammal populations remain stable = probably not virulent or B) major decline in small mammals follows increase in detection rate = probably virulent or at least cyclic.

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