Greater big-footed mouse (Macrotarsomys ingens)

Mohamed bin Zayed Species project number 14258646

Looking for the conservation strategy apropriate to the greater big-footed mouse in the dry forest of Ankarafantsika Nationa Park

Introduction
The greater big-footed mouse is endemic in Madagascar. It is classified as an endangered species (IUCN 2009) because it is only find in the dry forest of Ankarafantsika National Park (Garbutt 1999, Carleton and Schmidt , 1990), its range is less than 5,000 km ², the extent and quality of habitat and number of mature individuals continues to decline ( Soarimalala & Goodman , 2011). The research about its ecology and biology is rare.  Our research on October 2013 leads to the low population size of this species (only 11 individuals during 40 days). It is important to know the cause of this fact. It can be caused by pressures (predator and habitat disturbance) or its less range or its biology (low reproduction rate) or its social behavior (inter-species and intra-species competition). We need to know also the dynamic of the population; because our database in October 2013 has been the first data about this species, and we want to know if this population fluctuates. So, our research has 3 objectives:

 - Objective 1: knowing all factors leading to low effectiveness of the greater big-footed mouse: threats and pressures (all kinds of situation or creatures that can involve decline of the population such as predation and human activities or climate change); biology (all situations affecting the species population size such as the reproduction rate, the descendants development), social behavior (all types of competition that can provoke decline of the population size such as territory competition and food competition; it can be inter-species competition or intra-species competition or both).

- Objective 2: predicting the future size of the target species population: The research about the biology of this species will lead us to the number of litter per year, the number of descendants per litter with their development success rate (baby to mature)

- Objective 3: adopting the conservation strategy of this species: it is the last step for this project; it depends on the results of the objectives 1 and 2. The knowledge of the factors responsible for the low species population size and the future population size will help us to find the conservation strategy appropriate to the greater big-footed mouse.

 

I.                    Materials and Methods

I.1 Knowing and measuring all factors leading to the low strength of the greater big-footed mouse are important in order to increase its population size.

We need

·         to evaluate the suspicious threats and pressures (human activities, predator, and climate change) by counting them,

·         to study the biology and behavior by radio tracking every season (dry and wet season) during 3 years.

Four transect of 1 km have been established. The threats and pressures have been listed and evaluated as a frequency of appearance along each transect; so, we can classify them according to their importance. And at the same time, census of the target species have been carried out overnight along the transects, at 08 pm to 11 pm during 40 days. We captured each individual by hand and we recorded the position of each individual captured, marked and observed by using GPS (Global Positioning System). This method will provide us more information about the rhythm of activity, the season and the time of optimal activity.

The study of biology and social behavior has been reported at a later time because we are still waiting for the response from the financial backer about the radiotracking materials. So, the method of capture-mark-recapture has been adopted. We can get the territory surface with this method by linking all capture point (site) for each individual.

The radiotracking will be done twice per year (dry and wet season) during three years; it will provide us more information about the reproduction rate, the number of litter per year, the number of descendants per litter with their development success rate (baby to mature), all types of inter or intra-species competition such as territory and food, the rhythm of activity and the territory surface.

So, we did habitat study, because we need to complete our database and to confirm our last result. For that, 08 variables have been measured to determine if this species has a an habitat or food preference : Number of small trees , number of big trees, number of fallen trees , depth and coverage of the litter , ground cover, quantity of debris branches , average tree height. The measurement results will be tested by Kruskall-Wallis test. We need to test if there is a difference between sites with capture of Big Footed Mouse and sites without capture.

 

I.2. Predicting the future size of the target species population (still wait)

 The research about the biology of this species will provide us the number of litter per year and the number of descendants per litter with their development success rate (baby to mature). We will calculate the future population size by using that result to allow for the impact of pressures and threats in the Greater big-footed mouse.

This result will be useful to know and adopt the type of the conservation strategy appropriate to the target species.

 

I.3. Adopting the conservation strategy of this species (still wait)

The knowledge of the factors responsible for the low species population size and the future population size will help us to find the conservation strategy appropriate to the greater big-footed mouse.

 

I.4. Sensitization of the local population

It’s necessary in order to change the behavior of the local community. The method is based on the conference debate with local people for the protection of the greater big-footed mouse because local population doesn’t know its importance; they think that it's dangerous for their culture.

 

II.                  Results

II.1. Knowing and measuring all factors leading to the low strength of the greater big-footed mouse

·         Predation by wild cat and domestic dog

The main threats for Macrotarsomys ingens is predation by domestic dog and wild cat. On average 1 domestic dog per 4 observations (per 4 nights) were seen in all transects during 80 days of work.

Density of domestic dog:  d = N / S
d: Density of population (individuals/ha)
N: Number of individuals captured
S: surface (ha)
d = 20/400
d = 0.05 individuals/ha
 We can say that the principal predator of this species is domestic dog walking in the forest because we didn’t see wild cat there. The cause of this predation can be their overpopulation in the village. This animal is also helpful for hunting terrestrial animal such as Common Tenrec, the Hedghog shrew Tenrec,…..by using smell.

·         Habitat disturbance

Firstly, it’s caused by tourists and researchers going and coming. On average 5 tourists per day visit the park. So, 400 tourists have been observed during our stay there (80 days). And on average 2 researchers per day go and come twice a day in the forest during at least one month. These facts can have an impact to the greater big footed mouse.

Secondly, it’s caused by illicit entrance in the forest. Some people go to the forest for collecting some product like: medicinal plants, birds, common Tenrec ...In average 1 person per night have been observed in the forest during our nocturnal observation. We couldn’t measure the importance of the illicit entrance because didn’t have a précised information about that. We think that they come for hunting, for searching medicinal plant or precious woods. The illicit entrance can be caused by the poverty.

·         Biology and behavior

These study require radiotracking materials (radiometer, receptor,….); but till now we are still waiting for the response from the financial backer about that.

So, the method of capture-mark-recapture has been adopted in order to know if this species has foods or habitat preference. We can get the territory surface with this method by linking all capture point (site) for each individual.

The measurement results of 8 variables (annex 01) will be tested to determine the preference and requirement of habitat. SPSS software has been used to know which variable is important for the greater big-footed mouse.
The Kruskal -Wallis test will be applied to the data to see if there is a difference between the items with no capture and without capture.
Chart 01: Kruskall Wallis test for the litter depth

H (observed value)

5,046

H (critical value)

3,723

DF 1

 

One-tailed p-value

0,013

Alpha

0,05

The Kruskal-Wallis H is distributed as a Chi-square

The litter depth has a significant difference (p=0,013<0, 05). It means that litter is very useful for Macrotarsomys ingens, may be for its nest or for its foods. This species can’t live in open area.

·         Abundance of the greater big-footed mouse

10 individuals have been captured and marked during the present study (80 days).
d = N / S
d : Density of population ( individuals/ha )
N: Number of individuals captured
S: surface (ha)
d = 10/400
d = 0.025 individuals/ha
We didn't get the surface of territory because the number of captured individuals was not enough for that. It means that we didn't have any recaptured individuals.

·         Future size of the target species population (still wait)

·         The conservation strategy of this species (still in process): this species needs forest to survive because no forest means no litter. So, the appropriate strategy consists to conserve the totality of the forest.

·         Sensitization of the local population: the sensitization has been assisted by 54 persons. We did it in the village and everybody has been invited. We shared 75 T-SHIRT (with the park stuff), 50 brochures showing the pictures of the greater big-footed mouse and explaining its importance in the forest and in our life.

 

III.                Discussion

The greater big-footed mouse is very difficult to catch by box traps. It can be caused by its small population size. So, we used manual capture even if it was very difficult.
We didn't get the surface territory because, first, the greater big-footed mouse is difficult to catch by box traps, and second we didn't have recapture. The causes can be its large territory or its small population size.
The greater big-footed mouse has a habitat preference; it needs litter to live. The litter can be used for the nest and also for food searching (fruit and insect). We observed that almost of this species is terrestrial, but they climb tree to avoid predator.

At the moment, we don’t have information about biology and behavior of the greater big footed mouse because we are still waiting the materials for that. We need that data for predicting the future population size and adopting the conservation strategy appropriate for the greater big footed mouse.

Conclusion and recommendations
The greater big-footed mouse is rare in Ankarafantsika National Park. Domestic dog is its predator potential. Its protection is necessary to avoid the population decline. It needs forest to survive normally. We must control the entry of tourists and researchers and avoid the entry of domestic dogs in the forest. We suggest a breeding in captivity of the greater big footed mouse and then, we can move them in the natural habitat. But, this suggestion requires more information about biology and behavior, so we hope to reach that goal.

Next step

·         Study of biology and behavior: Radiotracking of the greater big footed mouse

·         Predicting population size

·         Adopting conservation strategy

·         Breeding in captivity