Phase 192 Science Report April-June 2019 · MGF 192 Science Report 2 STUDY AREA The Madagascar...

Acknowledgements

The author extends special thanks to the staff members that have assisted with the project, includingLindi Olivier, who helped handover to the new Research Officer at the beginning of the Phase, as wellas Kerry Lambourne, Nick Pearce, and Charlotte Møller. Additional thanks go to the many volunteerswho assisted with data collection and contributed to our project. Credit goes to Liam Curran for thephotograph used on the first page of this report. The Project Coordinator David Best deserves majorthanks for his management and support of the overall Madagascar Project, and as do the staff at LondonHQ for making this research possible, especially Alice Fields for her helpful feedback on this document.

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Contents

Acknowledgements 1

1 INTRODUCTION 31.1 Biogeography . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31.2 Species Diversity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

2 STUDY AREA 52.1 Phase 192 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52.2 Survey Routes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52.3 Habitat Types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

3 PROJECTS 83.1 Herpetofauna Project . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

3.1.1 Aims . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83.1.2 Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83.1.3 Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83.1.4 Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

3.2 Lemur Project . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113.2.1 Lemurs on Nosy Be . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113.2.2 Aims . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 123.2.3 Methodology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 123.2.4 Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 123.2.5 Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

3.3 Avifauna Project . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

4 Summary 15

5 Future Work 15

6 References 16

7 Appendix 19

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MGF 192 Science Report

1 INTRODUCTION

1.1 Biogeography

Madagascar’s unique and isolated evolutionary history, as well as its varied topography and climate,have produced remarkable levels of biodiversity and endemicity (Myers et al., 2000). The wildlife ofMadagascar includes some very old lineages but is dominated by taxa that are believed to have radiatedextensively after their arrival on the island via rafting (Nagy et al., 2003;Vences et al., 2003). Recentwork has also highlighted that this process has continued into recent geological time, with the currentfaunal assemblage containing many arrivals from the last few million years, the result of many raftingevents and highly mobile dispersers weakly constrained by sea barriers such as birds and bats (Samondset al., 2012). The arrival of humans is most widely accepted to have occurred approximately 2000 yearsago and both they and the animals they introduced have now made significant changes to the island’sfauna (Wang et al., 2019).The island of Nosy Be is particularly significant due to it being the type locality for many species and forits Lokobe National Park, a surviving portion (862 ha) of the original Sambirano forest of Nosy Be. Thisrepresents one part of what is believed to have been a network of areas of such forest in North-WesternMadagascar connected by forest corridors in the recent geological past, based on evidence such as theirsimilar reptile inventories (Andreone et al., 2003). Nosy Be has been regularly connected to the mainlandof Madagascar in the Quaternary, most recently about 8000 years ago, and all the islands in its groupwere merged into one landmass 15,000 years ago (Colonna et al., 1996). Hence it is an interesting casein that there are several endemic species of primate and herptile, which do not seem to have establishedthemselves on mainland Madagascar. However, some species previously thought endemic to Nosy Behave been discovered on surveys elsewhere, for example the Mantellid Boophis jaegeri (Andreone etal., 2003). While initially described on Nosy Be and believed endemic (Glaw & Vences 1992), it wassubsequently discovered on the Sahamalaza peninsula (Andreone et al., 2001). As work continues it ispossible more species thought unique to Lokobe or Nosy Be may be found to have wider distributions,with consequences for their conservation status.As elsewhere in Madagascar, the landscape of Nosy Be has been shaped by human agriculture, withplantations of coffee, ylang-ylang, and other crops occupying a large proportion of the island’s area. Inorder to clear land for pastoralists and rice agriculture, the traditional practice of tavy has been used.This method involves the cutting and then burning of an area of forest so that rain-irrigated rice orother crops can be planted, and then leaving the area to fallow until it has recovered to a state wherethis can be repeated, or the clearance of an area to retain a plant community conducive to zebu farming(Minten et al., 2003). While slash and burn allows for intensive agriculture in the cleared area, this isonly very short term and causes long term negative effects such as the washing away of nutrients, landerosion and the destruction of the microbial soil community (Styger et al., 2007). The loss of forest andproductive landscape has been aggravated by increasing population pressure, decreasing the time forwhich land is left fallow and resulting in the removal of surrounding forest areas, from which forest canmore effectively regrow on degraded landscapes. While the scale of deforestation in Madagascar is oftenentirely or mostly blamed on the combination of the practice of tavy and population growth, the landuse changes resulting from industries introduced since colonisation such as cash cropping (particularlyof coffee) and timber concessions were responsible for the loss of the majority of Madagascar’s primaryforest in the early 20th century, a period for part of which the practice of tavy was in fact banned bythe colonial government (Jarosz, 1993).There have been repeated calls by workers in Malagasy taxonomy for additional faunal surveys concen-trating on secondary and degraded habitats in Madagascar in order to establish in more detail the spatialdistribution of species of herpetofauna(e.g. Andreone et al., 2003, Irwin et al., 2010). The diversity inthese areas is far more poorly understood than that of the primary forests, but with the oldgrowthhabitat of Madagascar greatly shrunk and fragmented (Salmona et al., 2017) the role of other habitatsin species dispersal and as reservoirs of endemic Malagasy wildlife is of vital interest. Frontier’s studyarea situates us in a prime location to study the differences in faunal inventory in environments acrossa gradient of human disturbance levels and histories of clearance.


1.2 Species Diversity

The explanatory value of simple metrics of species richness and diversity has been questioned by someworkers in the field, especially after results such as Vellend et al. (2013) and Dornelas et al. (2014) thatran contrary to expectations in finding no significant local-scale diversity (alpha diversity) changes inspecies richness across large, global datasets spanning many biomes. While the validity of these papershas been brought into question (Gonzalez et al., 2016), and their results contradicted by meta-analysessuch as Murphy & Romanuk (2014) and Newbold et al. (2015), they have highlighted major differencesin the magnitude of measured species richness changes in different localities, with Newbold et al. findingonly a 13.6% reduction in within-sample richness globally, but up to a 76.5% reduction in the worstaffected habitats.It has been proposed that while the global trend is towards a decline in species diversity, with extinctionrates far exceeding the background rate estimated from the fossil record (Ceballos et al., 2015), localdiversity as measured by number of species per unit area within habitats is partially stable. While thismay seem counterintuitive, at least part of this effect is attributable to scenarios such as the replacementof specialist species only abundant locally with generalists of widespread distribution. This means thatthe total number of species in a large study area can decline while the locality sees its naive speciesrichness preserved, and can lead to misleading results based on narrow-scope studies (Thomas, 2013).This kind of change can be distinguished from a truly stable community in which vulnerable species arenot in decline by measuring and comparing beta-diversity. As the ratio between gamma (regional) andalpha (local) diversities, beta diversity reflects differences in community composition between differentstudy sites. Different kinds of disturbance due to human activity can have different effects on beta di-versity; for example, in cases where disturbance is patchy such as in selective logging a locality can seeits beta diversity remain stable or increase as generalist species colonise forest gaps. But equally, wherea natural ecosystem is wholly converted into an agricultural area shaped by humans for the cultivationof particular species beta-diversity can dramatically decline (Socolar et al., 2016).MGF’s study area allows us to use the species inventories of degraded, fragmented, primary and sec-ondary habitats in order to find beta diversity measurements that make our measures of species richnessmore useful by demonstrating whether specialist and threatened species are able to utilise cleared andfragmented habitats, or if they are being substituted for by abundant generalists. Our results in sur-veying herpetofauna and lemur diversity may be highly useful beyond these taxa, as in other studies inMadagascar which have found that beta-diversities in one group of animals can act as useful predictorsfor that of a much larger collection of organisms. In one notable case, lemurs act as successful predictorsof species richness and all components of beta diversity among carnivorans and rodents in forest ecosys-tems (Muldoon & Goodman, 2015).


2 STUDY AREA

The Madagascar Frontier project (MGF) is located on the eastern part of Nosy Be, Madagascar’s largestoffshore island (25,000 ha), located in the Diana Region of North-western Madagascar. Nosy Be lies∼8km from the mainland and is itself part of an offshore archipelago of several islands of significant sizeand many more small islets.The eastern region of the island contains Lokobe National Park, a surviving portion of the Sambiranoforest. The peninsula south-east of Lokobe is maintained by the villages of Ampasipohy, Ambalahonko,and Antafondro, which rely on agricultural areas including wet rice paddies, ylang-ylang and vanillaplantations, and a variety of other crops in MGF’s study area. A small amount of primary forest mostlycontiguous with Lokobe passes along the park’s margin, but further to the east towards the MGF campthis is replaced firstly with secondary forest of <40 years’ age and then degraded forest.Named after the Sambirano river, Sambirano forest is climatologically described as sub-humid forest,falling short of having the typical annual rainfall (only 225 cm, where a rainforest requires 250 cm) of arainforest. It represents a transitional zone between the perhumid Eastern Rainforest and the dry forestsof Western Madagascar, containing a mix of evergreen forests and scrub-dominated terrain adapted tothe pronounced dryness of the April-September dry season (Blumgart et al., 2017). There is a rainyseason peak in rainfall of 462 mm in January and a marked dry season with a minimum of 37 mm ofrainfall in July (Andreone et al., 2003). It is also marked by its sandstone substrate, as opposed to theigneous and metamorphic basement of its neighbour biomes; however, on the volcanic island of Nosy Be,both are present (Du Poy & Moat, 2003).Sambirano forest is the most recently developed of Madagascar’s biomes, having formed only eight mil-lion years ago as a result of increasing rainfall in the region (Wells 2003). However, it is the dominantform of forest in the speciose massifs of north-west Madagascar, which include many wildlife reserves, theStrict Nature Reserve of Tsaratanana, and the national parks of Lokobe and Montagne d’Ambre. Thesesurviving pockets of forest are believed to have recently been connected, a hypothesis supported by ge-netic evidence comparing certain species of herpetofauna from Tsaratanana, Manongarivo and Montagned’Ambre and indicating little divergence and very recent gene flow between the populations (Andreoneet al., 2009).

2.1 Phase 192

Phase 192 is synonymous with the second quarter of 2019, running from April to the end of June. Thisperiod includes the end of the rainy season and transition into the dry season. 2019 saw a late onset toMarch-May rains, but above average rainfall in the northern part of the country that continued longerthan usual into the dry season (NOAA, 2019). While some surveys during the early part of the phasewere suspended due to bad weather, this became much less common in May. The data analysed in thisreport has been collected between 1st April 2019 – 14th June 2019.

2.2 Survey Routes

MGF utilises 12 survey routes passing through a variety of terrains in the study area. These trails aredesigned to survey Primary (P1-3), Secondary (S1-3), Degraded (D1-3), and Corridor (C1-3) habitattypes (Fig 1). These routes are 400m in length and pass along pre-existing forest trails, some of whichare still in use by local people.


Figure 1: Transects in use by MGF. Green routes are primary forest, blue aresecondary forest, red are degraded forest and yellow are corridor transects. Madeusing QGIS and Google Satellite. Map data c©2019 Google.

2.3 Habitat Types

MGF separates the research area into four broad habitat types:

Primary: Native forest with little anthropogenic disturbance, characterised by a high canopy, oftenwith little understory (Fig. 2a).

Secondary: A mixture of native and planted trees, of medium canopy height with thick understory(Fig. 2b).

Degraded: Mostly open forest with high levels of anthropogenic disturbance, canopy height varies witha mixture of cleared areas, planted trees and perennials, ground cover highly variable throughout theyear (Fig. 2c).

Corridor: Describes transects passing through secondary forest with high levels of anthropogenic dis-turbance and the presence of agricultural areas, e.g. ylang-ylang plantations or rice paddies (Fig. 2d-f).This habitat type was introduced for this phase.


Figure 2: Examples of different habitat types found throughout the researcharea. Top to bottom, left to right: a. Primary, b. Secondary, c. Degraded. Theremaining images are of examples of locations on corridor routes; d. shows a routewith disturbed secondary forest on the left and a rice paddy on the right of thetransect; e. shows secondary forest to the left and fallow fields to the right; f.shows a banana plantation to the left and field border made of a line of trees onthe right of the transect.


3 PROJECTS

3.1 Herpetofauna Project

While research into the fauna of Nosy Be has been taking place for over 130 years, there are still newrecords being made, e.g. McLellan (2013) and Hyde-Roberts & Daly (2014). It has been noted that NosyBe is inhabited by a number of species which are mainly found in anthropogenic habitats and rarely inforests, and may undergo population explosions when areas are cleared for agriculture (Andreone et al.,2003). In addition to preserving the value of primary forest species, it is vital that researchers are able toestablish the species present in and reliant on degraded habitats, and also those able to utilise a varietyof habitat types in their life history.

3.1.1 Aims

• Determine if herpetile species diversity varies in our research area as a function of habitat type

• Determine what proportion of the gamma diversity is captured by different habitats in our studyarea

3.1.2 Methods

To locate herpetofauna, visual encounter surveys were employed, and all observations of reptiles andamphibians along our twelve 400m transects recorded. All transects were scheduled to be surveyed twicein the three-month survey period. Surveys were of two types: diurnal surveys beginning between 7 and10 am, and nocturnal surveys beginning between 7-7:30 pm. These times were chosen to ensure recordsat peak activity times for herptiles. Groups of at least three personnel, always including at least one staffmember as survey leader, began recording on arrival at the start of the transect and walked in single fileat a regular pace until its end. A two-metre separation between surveying personnel was observed.Nocturnal surveys were conducted using head torches for illumination. Weather conditions, such as thecloud cover present and whether there was or had been any recent rain, were also recorded. Surveys werenot performed when weather conditions were perceived as posing a significant danger, such as duringheavy rain.When a reptile or amphibian was located, the time of the observation and GPS co-ordinates wererecorded. A staff member trained in identification then identified the species, or made records and tookphotographs to identify the organism when back at camp. Measurements of the distance of the organismfrom the transect, its height above the ground, and the substrate it was located on were also taken usingeither a tape measure or handheld callipers. If the terrain or height of the organism prevented thesemeasurements from being taken, they were estimated by research staff.The routes used to access and perform the transect were pre-cut by the local population, and many arestill in frequent use. Whenever locals were found to be present on a transect the time and number ofpeople was recorded. A limitation of the routes used was the lack of access to certain routes (all primaryforest routes and one secondary) except at low tides, resulting in limits of how many surveys could beundertaken over the time period even when this was considered during survey scheduling.Both on and off survey periods, opportunistic data was recorded for the region’s inventory of herpeto-fauna. Data was analysed using R studio with the packages plyr, ggplot2, vegan, and betapart.

3.1.3 Results

A total of 340 herptile observations were made during surveys this phase, representing 29 different species.These consisted of 22 reptile species and 7 amphibian species, which were plotted on a species accumula-tion curve. This was found to be close to asymptotic (Fig 3). A calculation of estimated species richnessfrom all habitat types found an estimated four more species in the pool (33.125, using the chao estimator).

Observed abundance varied, with 6 (21% of all) species observed only a single time on surveys, consistingof Bloomersia wittei, Boophis brachychir, Brookesia minima, Calumma boettgeri, Gephyromantis granu-latus, and Ithycyphus miniatus. This contrasted with more frequently recorded species such as Brookesiastumpffi which was observed 82 times, making up 24% of all herptile observations. Presence data by


habitat is shown in Fig 4.

Multi-site dissimilarity tests (beta.multi, betapart package) performed on the species found in each habi-tat found a Simpson dissimilarity index of 0.5 and a Sorensen dissimilarity of 0.592 with a nestedresultantcomponent of 0.0918 between all habitats.The diversity of Primary habitats was found to be the most differentiated from the others in a prin-cipal component analysis of Sorensen dissimilarities (0.47 vs Secondary, 0.60 vs Degraded, and 0.57vs Corridor habitats) (Fig 5). Secondary forest had a dissimilarity of 0.46 vs Degraded habitat. Thelowest dissimilarities were between Corridor and the Secondary (0.33) and Degraded (0.31) habitat types.

Figure 3: Cumulative number of reptile and amphibian species observed over theApril-June survey period.

Figure 4: Presence of herptile species by habitat. Filled in dots denote that thespecies was only found in that habitat during surveys; species with a dot to theleft of the name abbreviation were only observed once in total during surveys. SeeAppendix for a list of full species names.


Figure 5: PCA distances based on Sorensen dissimilarities between habitat typesin survey area.

3.1.4 Discussion

Primary forest was found to have the most unique faunal assemblage in the dissimilarity analysis. Thisfits with the observation that seven of the observed species were found only in primary habitats; noother habitat type had more than two unique species observations. Of these, Sanzinia volontany wasalso observed twice on Primary routes outside herpetofaunal surveys, indicating that increased surveytime would make this difference more significant. The group of species shared by Primary forest andother habitat types such as Boophis tephraomystax and Trachylepis gravenhorstii were mostly composedof generalists found in all habitats. However, cryptic and threatened species such as the two species ofUroplatus were only found in Primary habitats.This leads towards the conclusion that threatened and endangered species such as Uroplatus speciesand Brookesia minima are unable to colonise other forms of habitat, and are reliant on the preserva-tion of primary forest to sustain their population. While some species such as Stumpffia pygmaea andZonosaurus rufipes have managed to recolonise the Secondary forest bordering our Primary habitat,many others have not, and may require a much older forest than the <40 year growth that has occurred.These two examples contributed to the higher similarity between Primary and Secondary than Primaryversus other habitats, but still leave the faunal assemblages highly distinct in the principal componentanalysis.Corridor forest was found to be closer to both Degraded and Secondary habitat than any other twohabitats were to each other. This matches our observation that Corridor forest consists of a mixture ofdegraded (agricultural and cleared) areas and secondary forest fragments.These results match the scenario raised in Thomas (2013) wherein a select number of generalist speciesare able to colonise cleared and secondary forest, but a large number of specialist species are unable tocross this threshold and become concentrated in shrinking and fragmented forest areas, which requireprotection to ensure their survival. Previous reports describe the greater species richness of primaryforest routes, but the addition of information about whether these species are able to utilise alternativehabitats has major conservation implications. It is notable that the new Corridor forest type also had ahigher species richness on surveys than Primary forests; generalists preferring both forested and clearedareas were present on these transects to the extent that more species were recorded than in Primaryhabitat.As this Phase included both the delayed end of the wet season in May and onset of the dry season, it wasexpected fewer species would be active than in the height of the wet season in Phase 191. This matchesthe lower total number of species observed (34 versus 29).


Several species were noted outside of herpetofaunal surveys, including Acrantophis madagascariensis,Dromicodryas bernieri, Dromicodryas quadrilineatus, Hemidactylus frenatus, Langaha madagascarien-sis, Mimophis occultus, Stumpffia psologlossa, and Thamnosophis stumpffi. This number is significantlygreater than the estimated number of species remaining in the pool after the survey effort and fits thegradient of the species accumulation curve poorly. Many of these were snake species, which fits withprevious reports mentioning their low detectability. Further research may help resolve how dependentupon different habitats they are (see Future Work).

3.2 Lemur Project

Modern lemurs are nearly exclusively arboreal and are commonly found in all layers of the Malagasycanopy (Behrens & Barnes, 2016). From the world’s smallest primate, the mouse lemur, to the largestextant lemur, the Indri, these animals occupy a broad range of ecological roles within their respectivehabitats (Herrera, 2017). While lemurs are generally predominantly frugivores, some species commonlyfeed on leaves, nectar, and opportunistically predate smaller animals such as small lizards (Garbutt,2007). Studies such as Bayart & Simmen (2005) have provided evidence that human disturbance effectslemur behaviour in ways such as home range area, group size, and feeding behaviour. The extensiveresearch of Seiler et al. (2014) examined the effect of a variety of variables on sportive lemur presenceand behaviour; the large number of Sportive lemurs found during Frontier’s lemur surveys led us toexamine whether we could test whether these correlates held true for the sportive lemurs of Nosy Be.

3.2.1 Lemurs on Nosy Be

Three species of lemur are found within MGF’s study area:

Claire’s Mouse Lemur (genus Microcebus)

Mouse lemurs are the smallest primates in the world. They have successfully colonised many forest types,preferring the lower forest layers with a high density of fine branches. Claire’s Mouse lemur (Microcebusmamirata) was first described as a distinct species in the early 2000s (Rasoloarison et al., 2000, Yoder etal., 2000). Claire’s Mouse lemur is medium-sized, nocturnal, solitary, and currently only known from theSambirano forest of Nosy Be (Behrens & Barnes, 2016). Conservation status: Critically Endangered(IUCN 3.1)

Hawk’s Sportive Lemur (genus Lepilemur)

The name Sportive lemur is derived from their powerful hind-legs, enabling them to leap considerabledistances. Hawk’s Sportive lemur (Lepilemur tymerlachsoni) is a large sportive lemur found in Sambiranotype forests. Its behaviour is primarily nocturnal and solitary. They are found in both from degraded toprimary forests (Andrews et al., 1998). They have been frequently observed utilising wooden nest boxesfixed into trees by a previous project in our study area, and are the only species seen to have done so inPhase 192. Conservation status: Critically Endangered (IUCN 3.1)

Black Lemur (genus Eulemur)

Black lemurs (Eulemur macaco macaco) are sexually dichromatic, with the males being dark brown toalmost black in colour and the females being golden-brown to chestnut-brown. Both sexes have tuftedears. They are diurnal lemurs that live in groups ranging from two to ten individuals (Colquhoun, 1993).Proportion and males and females are roughly equal in groups. Extent of nocturnal activity varies withlunar cycles due to variation in light availability. During the middle of the dry season (June-July),black lemurs are inactive at night, while spending the mornings sunning at the canopy apex. Duringthe dry period (October – December), nocturnal activity is dominant, coinciding with the fruiting ofcertain species of tree, and thus food availability. Black lemurs are found in both degraded areas andprimary forests, with larger groups more likely to occupy degraded habitats (Behren & Barnes, 2016).Conservation status: Vulnerable (IUCN 3.1)


3.2.2 Aims

• Determine if lemuriforme abundance varies in our research area as a function of habitat type.

• Determine if the height above ground at which lemurs are observed varies in our research area asa function of habitat type.

3.2.3 Methodology

Lemur surveys were conducted in a broadly similar way to those in the Herpetofauna project. Diurnalsurveys began between 7-10 am and nocturnal lemur surveys began between 7-7:30 pm. In daytime thecanopy was scanned visually for lemurs in the trees, and lemur boxes in the study area were noted to seeif any residents were visible, which were then recorded as ‘in box’.The measurements taken when a lemur was observed included the time and GPS co-ordinates, as wellas which of the lemur species it was, their distance from the path, and their height above the ground.These latter two measurements were estimated by trained staff as lemurs were largely too far from thepath for them to be measured.Nocturnal lemur surveys primarily relied on detecting eyeshine using headtorches. Only sightings whichcould be confirmed by a staff member were recorded.

3.2.4 Results

94 observations of lemurs or groups of lemurs were made during Phase 192, of which 82 (87%) wereof sportive lemurs. Only six observations of black lemurs were made during surveys in Phase 192; thesame number of mouse lemur observations were recorded. For this reason no analysis was performedon either of the two species. However, all species were observed in all habitat types, except that nomouse lemurs were observed during surveys on Corridor transects. The highest lemur abundance wasfound on Corridor transects, followed by Secondary; Degraded and Primary routes had less than half theabundance found in Corridor routes (Fig 6).

Figure 6: Number of lemurs observed in total on surveys by habitat.


To evaluate the assumption of normality, sportive lemur abundance data was tested for equality of vari-ance using Bartlett’s test in R. No significance was detected (K-squared = 0.73365, df = 3,p-value =0.8653). A one-way ANOVA was then conducted, and no significant difference was found at the 5%significance level (F(3,8) = 0.99; p=0.441).In order to compare the abundance data from this phase with previous reports, data was analysedagain without the Corridor habitat type. A Bartlett’s test found the assumption of normality satisfied(Ksquared = 0.50778, df = 2, p-value = 0.7758) and so a one-way ANOVA was also conducted. Thisalso found no significant difference at the 5% significance level (F(2,6) = 0.335; p=0.728).The height at which lemurs were observed was also compared between habitats. Mean height was high-est in Degraded habitat at 11.43m and lowest in Corridor habitats at 9.63m (Fig 7). The assumptionof equal variance was tested on height data using Bartlett’s test, and found to satisfy the assumption(Ksquared = 5.8223, df = 3, p-value = 0.1206). This was followed by a one-way ANOVA which detectedno significant difference at the 5% significance level (F(3,78)=0.388, p=0.762).

Figure 7: Heights of lemur observations in different habitats. Red points are themean value for that Habitat.

3.2.5 Discussion

Along with the Phase 191 Report, this analysis has produced a result conflicting with many previousreports that found a significant difference in abundance between habitat types, where Sportive lemurswere found to be significantly more abundant on Degraded transects. One explanation proposed forthis was the addition of the new Corridor habitat, which utilises sections of previous Degraded habitatsand includes secondary forest fragments, which could explain the shift from Degraded showing highestabundance to Corridor now demonstrating the highest level. However, when data was analysed withoutthe inclusion of Corridor transects no significant effect was detected. The number of Sportive lemursobserved during Phase 192 was comparable with those observed in studies finding a higher degradedabundance, with 82 in Phase 192 compared to 103 in Phase 183. However, Phase 182 found a veryhigh abundance on Secondary transects, despite a small sample size. It may be that this is the resultof a seasonal difference; additional data may help resolve this discrepancy, and demonstrate whetherSportives vary in habitat utilisation between different parts of the year.


The conclusion from this study that habitat has no strong effect on the height of lemur observationsis in conflict with Seiler’s (2012) previous study which found tree density and canopy cover had strongeffects on home range choice among Sportive lemurs on the Sahamalaza peninsula. Further details tolemur observations including canopy cover and number of nearby trees to an observation could providedata to test whether MGF’s Habitat classifications are not aligned with these variables at the locationsof lemur observations (see Future Work).

3.3 Avifauna Project

Due to a number of factors, no results from the MGF avifauna project are presented in this report.Surveys are currently underway and presence data continues to be collected, but insufficient surveyshave been performed to present any results at this time. After the departure of previous project staff, itwas not possible to collect all necessary data needed for avifauna surveys as no member was yet trainedin the calls and songs of the local species. After the staff had familiarised themselves with these, surveyswere attempted along the lines as in Phase 191 but found to be unsatisfactory in terms of survey pointplacement and lack of clarity in survey duration.The staff have since assembled a new set of survey points including sites with open and closed canopycover in primary and secondary forest, and a number of different degraded and agricultural habitat types.As per the previous phase, surveys are performed as point counts from pre-specified sites located in pri-mary and secondary forest, and agricultural areas. Surveys begin between 06:30 and 07:00 and consistof an initial 5 minute rest period, and then three ten minute survey periods separated by five minuterests. Visual and audio observations are recorded. On making an observation, the time is recorded, aswell as the species of bird. Its state is recorded as either V (visual, not in flight), F (flying, subject is inflight during observation) or A (audio, subject only detected by ear). Distance bands of 025, 25-50, or50+m were recorded.Data recorded for the avifauna project during this phase is intended to be analysed with that collectedin Phase 193.


4 Summary

In the two core survey types carried out by MGF, the data and analysis from Phase 192 has greatlybenefitted from the results of previous Phases to produce a more complex analysis and generate newresearch questions. The addition of measurements of beta-diversity to the Herpetofauna project hashelped understand the nature of the taxa shared between our habitat types and put the changes tospecies richness that have occurred locally in a global perspective. The absence of significant results incomparisons of abundance and height of Sportive lemurs between habitats is of interest as the formermay point to a seasonal variation which could be explored over the project’s continued activities in NosyBe, and the latter is in conflict with studies in similar habitats elsewhere in Madagascar. The collectionof more detailed observations to answer the questions this has developed may help clarify the ability ofthis species to utilise the degraded habitats of Nosy Be.

5 Future Work

Phase 193 aims to address the low detectability of certain species, which is currently believed to influencethe habitat data analysed in these reports, by establishing a pilot snake ecology project. In this project,snakes encountered in any location on or off a survey would be recorded with the time of the observation,location, weather and other information. This is intended to reveal the shortcomings of current surveysand reveal if the current low detectability is due to insufficient survey time, the times at which surveystake place, weather, or other factors.In order to generate data more comparable with previous studies such as Seiler (2012) and Seiler et al.(2014), new measurements are planned to be added to lemur surveys of canopy cover and a measurementof tree density in the locality.The avifauna project will be fully operational from the beginning of Phase 193, and include data recordedat the end of Phase 192.


6 References

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7 Appendix

List of species abbreviations:

Abbreviation Scientific Name Family IUCN Conservation Status

BLWIBloomersia wittei

(Guibe, 1974)Mantellidae -

BOBRBoophis brachychir

(Boetgger, 1882)Mantellidae

Vulnerable(decreasing)

BOTEBoophis tephraeomystax

(Dumeril, 1853)Mantellidae Least concern

BRMIBrookesia minima(Boettger, 1893)

ChameleonidaeEndangered(decreasing)

BRSTBrookesia stumpffi

(Boettger,1894)Chameleonidae Least concern

CABOCalumma boettgeri(Boulenger,1888)

Chameleonidae Least concern

CANACalumma nasutum

(Dumeril & Bibron, 1836)Chameleonidae Least concern

FUPAFurcifer pardalis(Cuvier, 1829)

Chameleonidae Least concern

GEGRGephyromantis granulatus

(Boettger, 1881)Mantellidae Least concern

GEMAGeckolepis maculata

(Peters, 1880)Gekkonidae Least concern

HEMEHemidactylus mercatorius

(Gray, 1842)Gekkonidae Least concern

HEPLHemidactylus platycephalus

(Peters, 1854)Gekkonidae -

ITMIIthycyphus miniatus

(Schlegel, 1837)Pseuoxyrhophiidae Least concern

LEMALeioheterodon madagascariensis

(Dumeril, Bibron & Dumeril, 1854)Pseuoxyrhophiidae Least concern

MACOMadagascarophis colubrinus

(Schlegel, 1837)Pseuoxyrhophiidae Least concern

MAEBMantella ebenaui(Boettger, 1880)

Mantellidae Least concern

PASTParoedura stumpffi

(Boettger, 1879)Gekkonidae Least concern

PHABPhelsuma abbotti(Boettger, 1879)

Gekkonidae Least concern

PHGRPhelsuma grandis

(Gray, 1870)Gekkonidae Least concern

PHLAPhelsuma laticauda

(Boettger, 1880)Gekkonidae Least concern

PHSEPhelsuma seippi

(Meier, 1987)Gekkonidae Endangered

PTMAPtychadena mascareniensis(Dumeril & Bibron, 1841)

Ptychadenidae Least Concern

SAVOSanzinia volontany(Reynolds, 2014)

Boidae -

STPYStumpffia pygmaea

(Vences & Glaw, 1991)Microhylidae

Endangered(decreasing)

TRGRTrachylepis gravenhorstii(Dumeril & Bibron, 1839)

Scincidae Least Concern

UREBUroplatus ebenaui(Boettger, 1879)

GekkonidaeVulnerable

(decreasing)


URHEUroplatus henkeli

(Bohme & Ibisch, 1990)Gekkonidae Vulnerable

ZOMAZonosaurus madagascariensis

(Gray, 1831)Gerrhosauridae Least concern

ZORUZonosaurus rufipes

(Boettger,1881)Gerrhosauridae

Near Threatened(decreasing)

Phase 192 Science Report April-June 2019 · MGF 192 Science Report 2 STUDY AREA The Madagascar...

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