Ndoki-Likouala Large Mammal Survey 2016-2017

RESULTS OF THE 2016-2017 LARGE MAMMAL SURVEY OF THE NDOKI-LIKOUALA LANDSCAPE

Design, planning, management, writing: Terry BRNCIC

Design and data collection: Team leaders: Bola MADZOKE, Christian NDZAI, Venant BOMOMO, Onesi SAMBA, Frelcia BAMBI, Joules ELARI, Ferré MBOUSSA; Assistants: Adrich MOUAMANA, Vigny MPAMBOURI, Phael MALONGA, Jess BAHAMBOULA, Arel MAPEMBI, Espoir MAGEMA, Christ MOUGANI, Aristide MOUELE, Gaston ABEA.

Data analysis: Terry BRNCIC, Fiona MAISELS, Samantha STRINDBERG

Ndoki-Likouala large mammal survey 2016-2017

CONTENTS Executive summary ...... 3 Introduction ...... 5 Ecological monitoring in the Ndoki-Likouala Landscape ...... 5 Methods ...... 6 Study area ...... 6 Survey design ...... 7 Implementation schedule ...... 9 Data collection ...... 10 Transect methodology ...... 10 Analysis ...... 11 Great ape nest determination ...... 11 DISTANCE analysis ...... 11 Comparison with 2006 and 2010-2011 survey data ...... 12 Results ...... 14 Great ape abundance and distribution ...... 14 Comparison with previous surveys ...... 15 Great ape distribution in the landscape ...... 18 Elephant abundance and distribution ...... 20 Comparison with previous surveys ...... 21 Elephant distribution in the landscape ...... 22 Ungulate relative abundance and distribution ...... 23 Comparison with previous surveys ...... 24 Ungulate distribution in the landscape ...... 25 Human sign abundance and distribution ...... 26 Human sign distribution in the landscape ...... 28 Comparison with previous surveys ...... 30 Other species distribution ...... 31 Red River Hog (Potamochoerus porcus) and Giant Forest Hog (Hylochoerus meinertzhageni) ...... 31 African Grey Parrot (Psittacus erithacus) ...... 33 Monkeys ...... 35 Forest Buffalo (Syncerus caffer nanus) ...... 37 Discussion and recommendations ...... 38 Elephants ...... 38 Great apes ...... 39 Ungulates ...... 39 Human impact ...... 39 Acknowledgements ...... 40 References ...... 41

Ndoki-Likouala large mammal survey 2016-2017

EXECUTIVE SUMMARY In northern Congo, a long-term monitoring program has been set up to repeat large mammal surveys in the Ndoki and Likouala landscapes every five years, estimating the density, abundance, and distribution of different large mammal species under different management systems and subject to different degrees of human pressure. The results of this monitoring help inform management decisions, assess the effectiveness of different management policies and practices, and monitor changes over time. We present here the results of the third round of monitoring, which took place from February 2016 to April 2017.

Although data on all large mammal species (and other species under threat such as African grey parrots) were collected during each survey, the main targets for which the surveys are principally designed to monitor are the abundance and distribution of elephants, great apes, ungulates (particularly duikers which are part of the bush meat trade), and signs of human impact.

The methodology used for estimating abundance was distance sampling, using line transects. The objects used for estimating animal abundance were elephant and ungulate dung and great ape nests. For each stratum, the sampling effort was based on minimizing the coefficient of variation for elephants, gorillas, and chimpanzees. Total transect effort was 703.5 km on 353 transects, covering nine strata and an area of 33,850 km2. A total of 347 km of guided recce was completed and more than 3,000 km of travel recces. More than 37,000 observations were recorded.

The estimated number of great apes in the Ndoki-Likouala landscape was around 56,000 weaned individuals (95% CI 47,700-69,400), including 43,500 gorillas (95% CI 36,700-51,100), and 11,500 chimpanzees (95% CI 9,400-13,900). Pokola and Loundoungou Forest management units (FMUs) had the highest number of gorillas, with approximately 9,300 and 9,900 gorillas respectively. Nouabalé-Ndoki National Park (NNNP) and the Loundoungou FMU held the largest number of chimpanzees with around 3000 chimpanzees each. Great ape populations have been stable or increasing over the last ten years.

Elephant abundance for all strata in the 2016-17 survey was 10,550 elephants in the landscape (95% CI 8705-12,566). The density of elephants was highest in NNNP with around 3000 individuals, followed by Pokola FMU with approximately 2,500 elephants. Elephant populations showed a significant increase from 2010 and 2016 in the NNNP, and were stable across the rest of the landscape over the last six years.

The highest dung density for ungulates was found outside of the park in the southern part of the Mokabi concession, followed by Loundoungou FMU. Kabo FMU had very low densities of ungulates, almost a third of that in NNNP. Between 2006 and 2016-17, the ungulate population showed a significant increase in Bailly and Lac Télé Community Reserve, and was stable in all other strata.

During the survey 26 elephant carcasses were found. Only two carcasses were observed on transects, one with signs of poaching, and the other where the cause of death remained unknown. 24 carcasses were found on travel recces (16 poached, six unknown cause, and two presumed natural deaths). Elephants killed by poachers were all found in the Kabo and Pokola concessions.

In 2016-17, Mokabi had the highest encounter rate of human signs. However, when looking only at hunting sign, Loundoungou swamp (primarily near Mokengui), Kabo FMU, and then Mokabi had the highest encounter rates of hunting signs. NNNP had the lowest encounter rate of all strata: 0.01 [0.00-

Ndoki-Likouala large mammal survey 2016-2017

0.04] signs/km. Compared with 2006 and 2010-11, no strata had a significant difference in the human encounter rate with the exception of a decrease in human signs in Pokola North in 2016.

For African Grey Parrots, we calculated the encounter rate per hour of observation on transects. 318 groups or individual parrots were seen or heard during 2440 hours of observation. Parrots were most frequently encountered Kabo FMU, followed by NNNP and Mokabi FMU. Parrots appeared to be scarce in swamps.

The most common monkey species encountered was the putty-nosed monkey (Cercopithecus nictitans). For all monkeys, NNNP had the highest encounter rate of all strata, with 1.81 groups of monkeys per km of transect in the park. After the putty-nosed monkey, the most common species were the crowned guenon (C. pogonias) and the gray-cheeked mangabey (Lophocebus albigena).

In summary, the Ndoki-Likouala landscape continues to be a reasonably safe haven for regionally important populations of large mammals, and for ten years the populations of flagship species have been stable, or even increasing in some strata. NNNP remains a stronghold for all animal species, with very few human signs in the park. Nevertheless, human activities completely surround the park, especially in the south with new logging roads in Kabo FMU, giving poachers easier access to the park. For large mammals with extensive home ranges – especially elephants – the results clearly demonstrated the benefits of the landscape management approach.

Ndoki-Likouala large mammal survey 2016-2017

INTRODUCTION

ECOLOGICAL MONITORING IN THE NDOKI-LIKOUALA LANDSCAPE The earliest surveys and research conducted by the Wildlife Conservation Society (WCS) in northern Congo from the late 1980s through to the mid- 1990s identified important populations of key wildlife species, such as forest elephant, gorilla, and chimpanzee (Blake 1993, 1994a, b, and c, 1995, 1996, Blake et al. 1997, Fay 1993, Fay & Agnagna 1991, 1992, Fay et al. 1989, Kano & Asato 1994). As a result, in collaboration with the Congolese Government and other international partners, both state and private, WCS set up three major conservation projects implementing three management strategies within the Ndoki-Likouala landscape: 1 ) Integral protection of wildlife and their habitat within a core protected area - Nouabalé-Ndoki National Park (WCS-Government agreement in 1991; gazetted as a Park in 1993), 2) Community conservation and management of wildlife and other natural resources in the Lac Télé Community Reserve (first study in 2000; gazetted in 2001), and 3) Wildlife management and conservation in commercial logging concessions (Forest Management Units or FMU), conducted in collaboration with an international logging company Congolaise Industrielle de Bois (CIB – now OLAM) through the Program for the management of the ecosystems of the park and its periphery (PROGEPP) (agreement signed in 2000). As a result, a total of 22,354 km² (78%, of the entire landscape) benefits from better conservation management. The goal of these programs is to conserve biodiversity and ecosystem integrity, including target populations of forest elephants, great apes, and other key wildlife species, across the Ndoki-Likouala landscape.

To evaluate the impacts of these different forms of management, WCS has set up a regular monitoring program for large mammal populations in the Ndoki-Likouala landscape. The results of this monitoring help inform management decisions, assess the effectiveness of different management policies and practices, and monitor changes over time.

To this end, a long-term monitoring program has been set up to repeat large mammal surveys at the landscape scale every five years, estimating the density and abundance of different large mammal species under different management systems and subject to different degrees of human pressure. The first iteration, which established the methodology both in this and five other landscapes across central Africa, was carried out as part of the CITES-MIKE project and only included NNNP and the Mokabi concession (MIKE 2005), and only included elephant, great ape, and human sign. In 2006, the first wildlife transect survey of the entire landscape revealed that it was still of great importance for the conservation of gorillas, chimpanzees, and forest elephants (Stokes et al., 2010). In 2010-2011, a second survey was conducted, which revealed that in some strata there were significant reductions in elephant and duiker densities as well as changes in human impact due to logging activities (WCS report Maisels 2012). In 2016-2017, a third survey was conducted, the results of which are reported here.

To train a new cadre of researchers capable of conducting such a study, and to retrain experienced researchers, a one-month training course on standardized methodology (Kühl et al., 2008, Maisels & Aba'a 2010, Maisels et al. 2008a, Maisels et al., 2008b) was conducted in November 2015 for the ten new assistants recruited, two WCS research assistants, four experienced team leaders, and two CNIAF

Ndoki-Likouala large mammal survey 2016-2017

(the Congolese National Center for Inventory and Management of Forest and Wildlife Resources) staff. The training included modules on the scientific approach, an introduction to statistics, knowledge of animals, the practice of field methodologies, new technologies, and the manipulation and understanding of various analytical and GIS software packages.

METHODS

STUDY AREA The landscape of Ndoki-Likouala covers an area of nearly 34 000 km2, consisting of dense tropical Guineo-Congolese forest, swamps, and flooded savannahs between the Sangha and Oubangui rivers in northern Congo-Brazzaville (figure 2a). The landscape includes protected areas (NNNP, IUCN Protected Area Category II), natural resource management zones (Lake Tele Community Reserve: IUCN Category VI), multiple use forests managed for wildlife protection and sustainable harvesting of timber (Forest Stewardship Council (FSC)) certified concessions -Pokola, Loundoungou, and Kabo), and forestry concessions without an official strategy for reduced-impact logging or wildlife protection (Mokabi). The Loundoungou, Bailly, and Batanga swamps currently have no management status or strategy, but they represent an important habitat for great apes, dwarf crocodiles, and other swamp forest fauna and flora (figure 2b). The landscape contains regionally important populations of great apes, elephants, and other forest mammal species, such as bongo (Tragelaphus eurycerus), forest buffalo (Syncerus caffer nanus), and many duiker species. Human population densities vary, being zero inside the national park, but higher elsewhere. In 2014, all the CIB concessions (all the villages, and the logging towns of Pokola, Kabo, Loundoungou combined) held over 25,000 people, with Pokola alone holding over 13,000 (CIB census figures). The Lac Tele Community Reserve has 17,000 people living within its limits; again many are concentrated in the town of Epena, but villages are strung along all of the rivers and along the Epena to Impfondo road.

The seasonality of the climate is typically bimodal, with a long dry season between December and February and a long rainy season between August and October (figure 1). The annual rainfall during the three years of the surveys, measured in Bomassa, shows the differences between years and an average for the zone (figures 1 and 3). Recurrent irregular El Niño Southern Oscillation (ENSO) cycles occur, and ENSO events happened in 2010 and 2014-2016, though the effect and timing on Central Africa is not clear. These events could have contributed to the lower than normal rainfall in Bomassa from Jan-Feb 2016 and to higher than normal rainfall from Apr-June 2016 and in July 2010.

Ndoki-Likouala large mammal survey 2016-2017

Figure 1. Average monthly rainfall between 2001 and 2017 in Bomassa, Congo (TEAM, WCS) and comparison with survey months for all surveys Rainfall during survey months and average rainfall 2001-2017 500 450 400 Mean 2001-17 350 300 2006 mm 250 2010 200 2011 150 2016 100 2017 50 0 Jan Fev Mar Avr Mai Jun Jul Aou Sep Oct Nov Dec

SURVEY DESIGN

The delineated strata correspond to the administrative boundaries of protected areas and forest concessions in order to better meet the objectives of assessing different types of management. The only exception was the Mokabi FMU where only the southern sector of the concession was sampled (hereafter called Mokabi FMU South). A previous survey of the whole area up to the Central African Republic (CAR) border (Bourges & Mpati 1996) and a subsequent one as far north as the Ibenga river (Boudjan 2003) showed that the northern part of the concession was already depleted of elephant and great ape populations, and therefore was not a priority for monitoring. A 3-km buffer around each village was excluded from the sampling area to avoid agricultural areas.

The survey design (placement of transects) was done with Distance software using the 'Systematic Segmented Trackline Sampling' option (Buckland et al., 2001, Thomas et al., 2010, Strindberg et al., 2004). To improve the accuracy of the results, the orientation of transects in each stratum was perpendicular to the main elements that can create a gradient in animal density (roads, main rivers). The sampling effort used was a compromise between the need for sufficient precision to detect change over time, and logistical, financial and human resource constraints. The precision target for this study was to have a coefficient of variation (% CV) of less than 15% for the landscape for elephants, gorillas, and chimpanzees, as these were the focal species of the study. The estimate of the level of effort required was based on the results of the 2010-2011 survey, using the Buckland et al. 2001 method (section 7.2.2.1).

The final design included 354 transects of 2-km length and 354 guided recces of 1-km length, covering nine strata and an area of 33,850 km2 (table 1). The number of transects in each stratum ranged from 18 to 51. During movement between transects, the distance was covered by travel recces, used to collect data on the presence and distribution of human activities.

Ndoki-Likouala large mammal survey 2016-2017

Figure 2. a) Ndoki-Likouala landscape vegetation and infrastructure map, and b) The 2016-2017 sampling plan. Strata outlined in orange correspond to strata in common with the 2006 survey (see table 3).

Due to extreme flooding in May, one of the transects was not completed, for a total effort of 703.5 km on 353 transects (table 1). A total of 347 km of guided recce was completed, and more than 3,000 km of travel recce was walked. More than 37,000 observations were recorded.

Ndoki-Likouala large mammal survey 2016-2017

Table 1. The Ndoki-Likouala 2016-17 survey strata and distance traveled. Survey Area No. No. Transects Km Strata (sq. km) Transects walked walked Bailly swamp 5,477 41 41 81.3 Batanga 2,276 41 41 81.0 Kabo FMU 2,773 51 51 101.6 Lac Télé Community Reserve 4,219 43 43 85.8 Loundoungou FMU 5,455 35 35 69.8 Loundoungou swamp 3,028 34 34 68.0 Mokabi FMU (south) 1,753 18 18 36.0 Nouabalé-Ndoki NP 4,071 45 45 90.0 Pokola FMU 4,797 46 45 90.0 Total 33,849 354 353 703.5

IMPLEMENTATION SCHEDULE The study was conducted in two phases (one phase between Feb-Sep 2016 and the second from Jan-Apr 2017) (table 2). The schedule was based on (i) the timing of the 2006 and 2010-11 surveys that were conducted between February and August and (ii) taking advantage of the low water level in the first half of the year. Thus, between February and June 2016, the wetlands of Loundoungou and Bailly were completed, and the swamp strata of Lac Télé and Batanga were completed between February and April 2017.

Table 2. The months in which the survey was carried out in each stratum. Darker grey indicates when the majority of transects were walked for that stratum. Month Strata J F M A M J J A S 2016 Loundoungou swamp Loundoungou FMU Bailly swamp Kabo FMU NNNP Pokola FMU 2017 Mokabi FMU (south) Lac Tele CR Batanga

Strata were planned to be surveyed at the same time of year as the two previous surveys to minimize differences in climatic conditions. However, even within the same month, rainfall varies annually, and these differences may have an impact on the rate of degradation of dung and nests. Figure 3 shows the intra-annual difference in rainfall (measured at Bomassa) for the month before and the months during which a stratum was surveyed. These results show that the year 2010 had a slight increase of rainfall compared to 2006 and 2016-17.

Ndoki-Likouala large mammal survey 2016-2017

Figure 3. Rainfall measured at Bomassa during survey of each stratum. Each bar represents the average rainfall for the months during and one month before each stratum was surveyed.

A maximum of seven teams were deployed at the same time in the same stratum to complete each stratum in as short a time as possible. Each team consisted of two observers (one for tree nests, and one for ground signs), a compass bearer, a transect cutter, and a group of porters (locally recruited).

DATA COLLECTION TRANSECT METHODOLOGY At the start of each transect, basic habitat variables were recorded, and every 250m thereafter. If the vegetation type changed along the transect between the 250 m blocks, it was duly noted. All signs of mammal presence were recorded on transects and guided recces (such as nests, dung, feeding, tracks, carcasses, resting spots, etc.). Signs of human activity were noted on transects and all recces.

Animal density (elephants and apes) was estimated using standardized Distance sampling methodology for line transects (Buckland et al., 2001, Thomas et al., 2010). Ape densities (gorillas and chimpanzees) used nest counts; and elephant densities used dung counts. Relative abundance of small, medium, and large classes of ungulates (primarily duikers) was estimated from dung density (we cannot estimate animal density as we have no dung production rates for these species for this landscape, and are unsure of dung decay rates: the only existing study (Breuer et al. 2009) showed very rapid decay rates, a potential confounding effect of dung beetles and suggested that habitat type also affects decay rate). The perpendicular distance was measured to the nearest centimeter from the transect line to the center of the sign. A series of covariates was also recorded for each sign (vegetation type/ slope/ age of sign, etc).

All data was entered directly into a rugged smartphone in the field with the Cybertracker application, and imported into a SMART database upon return from the mission. GPS track logs were recorded for every mission and a GPS waypoint was recorded for every sign.

APE NESTS Due to logistical constraints, a preliminary study on the rate of degradation of nests (and elephant) dung for the different strata was not done. However, this landscape contains an ongoing great ape study that started in 1999 (in the Goualougo Triangle, in the south of the Nouabalé-Ndoki NP). To convert nest density to great ape density, the rate of nest degradation was therefore taken from an intensive nest decay study at Goualougo, (Morgan et al. 2014), which estimated the average degradation time of an ape nest to be 146.4 (SE 3.0) days. For chimpanzees, the degradation time used was 143.8 (SE 7.86) days, and for gorillas, the nest degradation time used was 149.1 (SE 8.32) days. The nest construction rate of chimpanzees was estimated to be 1.09 (SE 0.05) nests per day in NNNP (Morgan et al., 2006).

Ndoki-Likouala large mammal survey 2016-2017

This construction rate was also used for gorillas, which have been observed sometimes building more than one nest per day like chimpanzees.

In order to discriminate between old chimpanzee and gorilla nests built in trees, multiple characteristics (covariates) were recorded for each nest encountered on a transect. The factors noted were: Construction type (ex. woody, herbaceous, bare ground), forest type, nest height, tree species used, openness of understory below the nest, and canopy openness above the nest. Fresh nests were directly assigned to a species if verifying signs (feces, odor, or hair) were present. Nest groups were defined as all nests created by the same ape species and of the same age class created less than 50 m from each other. If one nest of a group was found on the ground, the whole group was assigned to gorillas, as chimpanzees have not been recorded building ground night nests in this region.

ELEPHANT DUNG CLASSES For elephants, we used a dung production rate of 19.76 (SE 0.23) dung per day from a study in Cameroon (Tchamba 1992). The degradation rate of 51.3 (SE 2.81) days was obtained from a study conducted in NNNP over a three year priod (Breuer et al., 2007). Dung was classed in the field according to the MIKE ‘S’ classification system (Hedges and Lawson 2006) based on their state of structural decomposition.

The tables presented in this report show estimates of sign densities as well as animal densities (using these conversion factors).

ANALYSIS GREAT APE NEST DETERMINATION For 2016-17, a total of 4530 nests were recorded on transects, of which 1408 were assigned to gorillas based on field characteristics, 141 were attributed to chimpanzees, and 2981 were attributed to unknown 'great apes'. To correctly assign unknown nests to a species, log-linear regression models were created using different combinations of the variables associated with nests (Sanz et al. 2007). When the model assigned different species to nests in the same group, nests were manually reassigned to one species.

DISTANCE ANALYSIS Preliminary analyses of the linear transect data were done at Epena, Congo in April 2017. The team leaders and assistants who performed the field work, the Assistant Conservator, the Lac Tele SMART Focal Point, and two collaborators from CNIAF (the Congolese National Center for Inventory and Management of Forest and Wildlife Resources) attended the training. Final analyses on the cleaned dataset were completed by T. Brncic.

DISTANCE 7.0 software (Thomas et al. 2010) was used to evaluate the detection probability, density, and abundance of elephants, gorillas, and chimpanzees, and the density of ungulate dung for each stratum. The MCDS (Multi-covariant DISTANCE Sampling) option was used to control the influence of factors such as nest height, undergrowth density, forest type, sign age, and observers on the detection function.

We used a global model to fit the detection function, but calculated density estimates at the stratum level. AIC was used in model selection and the results of the χ2 goodness-of-fit test were also considered. The variance of density at the landscape level was estimated using the bootstrap method.

Ndoki-Likouala large mammal survey 2016-2017

COMPARISON WITH 2006 AND 2010-2011 SURVEY DATA To compare the 2016-17 results with previous surveys, the boundaries of each stratum were reconfigured to conform to the original 2006 strata, which were generally the smallest (with the exception of Mokabi). For example, the Pokola stratum sampled in 2006 was divided between several larger strata in 2010, and was larger in 2017, so the common limits used for intra-year comparison were the 2006 Pokola boundaries (see figure 2b). All transect outside these common boundaries were removed from the analysis of the data, and the density of transects was harmonized across the stratum, removing some transects if necessary (table 3). Raw data from 2006 and 2010-11 surveys was completely re-analyzed using the common strata using the same rates of production and degradation of the great ape nests and elephant dung.

Ndoki-Likouala large mammal survey 2016-2017

Table 3. Details of the reconfiguration of transects and strata boundaries from the different survey years to make common, comparable strata (see figure 2b). Area used for Changes made to each survey stratum Common analysis strata (km2) 2006 2010-2011 2016-2017 Mokabi FMU 1,753 Reduced to 2017 stratum NA 2017 stratum South 10 transects 18 transects NNNP 4,071 2006 stratum 2 strata combined: Removed 15 2017 stratum 20 transects transects from ‘NNNP N’ to have 45 transects same density of transects as ‘NNNP S’. 49 transects Kabo FMU 2,773 2006 stratum 2 strata combined: 2017 stratum 15 transects Retained 2 transects from ‘Low Ele 51 transects Density’ stratum; 14 transects from ‘High Ele Density’ 16 transects Pokola FMU 4,502 2006 stratum (smaller 2 strata combined: Reduced to 2006 stratum. North than 2017 Pokola FMU) Retained 6 transects from ‘Low Ele Took out southern 7 21 transects Density’; transects. 14 transects from ‘High Ele 38 transects Density’, 1 transect from ‘Bailly North’. 21 transects Loundoungou 4,228 2006 stratum (mix of 3 strata combined: 2 strata combined: North terra firma and swamp 2 transects from ‘High Ele Density’, 18 transects from forest) 30 transects from ‘Loundoungou ‘Loundoungou FMU’, 9 18 transects TF’, 1’ transects from transects from ‘Loundoungou swamp’. ‘Loundoungou swamp’ No change in density. 27 transects 46 transects Bailly North 5,792 2006 stratum (mix of 3 strata combined: 3 strata combined: Loundoungou FMU with 18 transects from ‘Bailly North’, 7 18 transects from ‘Bailly’, 16 unattributed swamps) transects from ‘High Ele Density’, transects from 24 transects 12 transects from ‘Loundoungou ‘Loundoungou FMU’, 13 swamp’. transects from 37 transects ‘Loundoungou swamp’. 47 transects Lac Tele CR 4,219 3 Strata combined: 2 strata combined: 2017 stratum 17 transects from ‘Lac 14 transects from (Bailly S and Lac 43 transects Tele swamp’, 6 transects Tele S’, 33 transects from ‘Lac Tele from ‘Lac Tele TF’, 21 N’ transects from ‘Lac Tele 47 transects Seasonally Inundated’ 44 transects Landscape 27,338 All strata used. Of 166 All strata used. Of 280 completed Batanga not included in transects completed, 5 transects, 34 removed for density, comparison. Of 353 removed for area, 9 31 removed for area. completed transects, 84 removed for density. 216 transects used for comparison removed for area. 152 transects used for (509 km) 269 transects used for comparison (302 km) comparison (524 km)

Ndoki-Likouala large mammal survey 2016-2017

RESULTS

GREAT APE ABUNDANCE AND DISTRIBUTION The estimated number of great apes in the Ndoki-Likouala landscape was around 56,000 weaned individuals, including 43,500 gorillas, and 11,500 chimpanzees (table 4). The stratum with the highest density of gorillas was Batanga, with 2.59 gorillas / km2, for a total of almost 6,000 gorillas. The Pokola and Loundoungou FMUs had the highest number of gorillas, with 9,300 and 9,900 gorillas respectively.

The most important stratum for chimpanzees was the Nouabalé-Ndoki National Park, with a density of 0.74 chimpanzees/km2 (3,000 weaned individuals). Loundoungou FMU was also rich in chimpanzees with around 2,700 chimpanzees in this stratum. These two strata contain more than 50% of the chimpanzee population in the landscape.

Ndoki-Likouala large mammal survey 2016-2017

Table 4. Estimates for the density of nests, density of great apes, and abundance of great apes in each stratum and the Ndoki-Likouala landscape for 2016-17 survey. Nest construction rate used for all great apes: 1.09 (SE 0.05) (Morgan et al., 2006). Nest degradation rate for gorillas: 149.1 (SE 8.32); chimpanzees: 143.8 (SE 7.86); and all great apes: 146.4 (SE 3.0) (Morgan et al., 2014). N Species Stratum km nests Nests/km2 [95% CI] CV % Ind/km2 [95% CI] CV % N [95% CI] Bailly swamp 81.3 143 56 [33-95] 26.4 0.35 [0.20-0.60] 27.4 1,900 [1,107-3,260] Batanga 81 842 422 [250-711] 26.3 2.59 [1.51-4.45] 27.3 5,905 [3,446-10,120] Kabo FMU 101.6 559 234 [179-307] 13.5 1.44 [1.07-1.95] 15.3 3,997 [2,954-5,408] Lac Télé CR 85.8 428 260 [136-499] 33.1 1.60 [0.83-3.11] 33.8 6,761 [3,487-13,109] Loundoungou swamp 69.8 164 94 [57-156] 25.2 0.58 [0.34-0.97] 26.2 1,754 [1,043-2,948] 68

Gorillas Loundoungou FMU 270 296 [185-473] 23.6 1.82 [1.12-2.97] 24.7 9,921 [6,082-16,181] Mokabi FMU South 36 41 67 [27-164] 45.3 0.41 [0.17-1.02] 45.9 719 [290-1,782] Nouabalé-Ndoki NP 90 165 87 [59-127] 19.3 0.53 [0.35-0.80] 20.6 2,168 [1,443-3,257] Pokola FMU 90 508 317 [225-447] 17.2 1.95 [1.35-2.83] 18.7 9,368 [6,474-13,556] NL Landscape 703.5 3120 209 [175-248] 9.7 1.28 [1.08-1.51] 9.52 43,415 [36,703-51,119]

Bailly swamp 81.3 120 42 [26-69] 24.7 0.27 [0.16-0.45] 25.7 1,477 [889-2,455] Batanga 81 79 31 [15-62] 35.4 0.20 [0.10-0.40] 36.2 448 [221-906] Kabo FMU 101.6 215 47 [29-75] 24.1 0.30 [0.18-0.49] 25.1 824 [502-1,351] Lac Télé CR 85.8 68 25 [12-53] 39.2 0.16 [0.07-0.34] 39.9 669 [309-1,448] Loundoungou swamp 69.8 120 46 [27-80] 27.5 0.30 [0.17-0.52] 28.4 898 [512-1,575] Loundoungou FMU 68 210 80 [52-122] 21.1 0.51 [0.33-0.79] 22.3 2,784 [1,789-4,335]

Chimpanzees Mokabi FMU South 36 35 29 [13-65] 40.1 0.19 [0.08-0.42] 40.7 327 [145-737] Nouabalé-Ndoki NP 90 446 116 [79-170] 19.1 0.74 [0.49-1.11] 20.4 3,018 [2,015-4,521] Pokola FMU 90 117 33 [17-63] 32.7 0.21 [0.11-0.41] 33.5 1,012 [526-1,946] NL Landscape 703.5 1410 53 [44-64] 10.1 0.34 [0.28-0.41] 10.08 11,522 [9,370-13,890]

Bailly swamp 81.3 263 100 [70-145] 18.3 0.63 [0.43-0.92] 19.0 3,443 [2,359-5,025] Batanga 81 921 433 [270-694] 23.7 2.71 [1.68-4.39] 24.2 6,177 [3,819-9,992] Kabo FMU 101.6 774 274 [216-349] 12.1 1.72 [1.33-2.23] 13.1 4,764 [3,678-6,171] Lac Télé CR 85.8 496 309 [166-575] 31.6 1.93 [1.03-3.63] 32.0 8,158 [4,351-15,297] Loundoungou swamp 69.8 284 147 [103-210] 17.8 0.92 [0.64-1.33] 18.5 2,784 [1,924-4,029] Loundoungou FMU 68 480 403 [300-542] 14.8 2.52 [1.85-3.44] 15.6 13,767 [10,089-18,786]

Great apes Mokabi FMU South 36 76 96 [52-177] 30.0 0.60 [0.33-1.11] 30.4 1,055 [570-1,951] Nouabalé-Ndoki NP 90 611 198 [143-274] 16.3 1.24 [0.88-1.74] 17.1 5,043 [3,591-7,082] Pokola FMU 90 625 369 [263-518] 17.0 2.31 [1.62-3.29] 17.7 11,082 [7,793-15,760] NL Landscape 703.5 4,530 266 [228-312] 9.19 1.66 [1.41-2.05] 9.53 56,275 [47,692-69,362]

COMPARISON WITH PREVIOUS SURVEYS Repetition of large mammal surveys in 2006, 2010-11, and 2016-17, using the same methods, has allowed us to detect trends in animal populations. The gorilla and chimpanzee population was stable between 2006 and 2016-17 without any statistically significant change in population (table 5). The density and number of gorillas in the Bailly north stratum increased between 2006 and 2016. This increase was probably due to the fact that the stratification in 2016-17 separated the part of Loundoungou terra firma (very rich in gorillas) from the Bailly swamp and placed more transects in the terra firma forest. When strata were combined to match the strata used in 2006 (table 3), the increase in terra firma transects contributed to the high density of gorillas for 2016-17. Thus, the difference in the population of gorillas in the Bailly North stratum was an effect of re-stratification and does not represent an increase in the population.

Ndoki-Likouala large mammal survey 2016-2017

At the Ndoki-Likouala landscape level, there was no significant change in gorilla abundance between the three surveys (tables 5 and 6).

Figure 4. Comparison of number of gorillas in each survey stratum by survey year 25000

20000

15000 2006

10000 2010-11 2016-17

Number of of gorillas Number 5000

0 Bailly north Kabo FMU Lac Tele CR Loundoungou Mokabi FMU Nouabale-Ndoki Pokola FMU north South NP north

Figure 5. Change in the number of (a) chimpanzees and (b) gorillas in the Ndoki-Likouala landscape for the three survey periods. These estimates do not include the Mokabi stratum, which was only surveyed in 2006 and 2016. Abundance of chimpanzees Abundance of gorillas by by survey year survey year 14000 60000 12000 50000 10000 40000 2006 2006 8000 2010-11 30000 2010-11 6000 2016-17 2016-17 20000 4000

2000 gorillas of Number 10000 Number of chimpanzees of Number 0 0 NL landscape (without Mokabi) NL landscape (without Mokabi)

Figure 6. Comparison of number of chimpanzees in each survey stratum by survey year 5000

4000

3000 2006 2000 2010-11 2016-17 1000

Number o chimpanzees o Number 0 Bailly north Kabo FMU Lac Tele CR Loundoungou Mokabi FMU Nouabale-Ndoki Pokola FMU north South NP north

Ndoki-Likouala large mammal survey 2016-2017

Table 5. Comparison of great ape nest densities between the three survey periods. The p-values for the difference between each period are given in the last columns. P-values that are significant at p ≤ 0.05 are in red. Nest Density 2006 2010-11 2016-17 p-value for significant diff 2006 -- 2006 -- 2010-11 -- Species Stratum Nests/km2 [95% CI] CV% Nests/km2 [95% CI] CV% Nests/km2 [95% CI] CV% 2010-11 2016-17 2016-17 Bailly north 78 [37-164] 37.5 192 [112-328] 27.0 238 [164-345] 18.7 0.06 0.003↑ 0.50 Kabo FMU 240 [111-521] 37.6 182 [65-508] 51.5 255 [195-333] 13.4 0.65 0.88 0.46 Lac Tele CR 145 [90-232] 23.7 229 [113-465] 36.4 282 [148-539] 33.0 0.35 0.17 0.67 Loundoungou north 72 [29-179] 45.5 101 [57-178] 28.7 165 [79-341] 36.8 0.52 0.18 0.34

Gorilla Mokabi FMU South 10 [2-50] 82.3 66 [27-162] 45.1 0.07 Nouabale-Ndoki NP 60 [29-121] 35.4 55 [34-89] 24.5 94 [64-138] 19.4 0.85 0.22 0.08 Pokola FMU north 454 [243-848] 30.7 655 [349-1228] 30.9 390 [271-560] 18.1 0.41 0.68 0.22 NL Landscape 158 [107-211] 16.9 242 [165-325] 16.9 228 [187-284] 10.6 0.09 0.05↑ 0.77

Bailly north 37 [20-69] 30.9 69 [37-130] 32.1 63 [41-98] 22.2 0.20 0.15 0.82 Kabo FMU 35 [20-59] 25.4 22 [10-47] 37.0 46 [29-74] 23.9 0.30 0.41 0.08 Lac Tele CR 17 [8-36] 40.1 27 [16-45] 25.5 24 [11-51] 39.2 0.27 0.53 0.78 Loundoungou north 60 [31-115] 32.1 45 [31-66] 19.0 73 [46-115] 22.8 0.49 0.61 0.14 Mokabi FMU South 6 [2-27] 74.6 29 [13-66] 40.3 0.07

Chimpanzee Nouabale-Ndoki NP 98 [58-166] 25.6 79 [55-115] 18.7 119 [81-174] 19.2 0.52 0.54 0.15 Pokola FMU north 37 [16-85] 42.1 49 [28-88] 28.6 35 [18-69] 34.7 0.55 0.93 0.44 NL Landscape 44 [29-56] 17.2 49 [35-64] 14.7 60 [48-73] 11.0 0.57 0.10 0.30

Bailly north 117 [72-189] 23.9 256 [161-407] 23.2 311 [238-408] 13.5 0.03↑ 0.0001↑ 0.45 Kabo FMU 264 [149-466] 27.3 260 [113-599] 41.1 283 [222-360] 12.1 0.97 0.81 0.84 Lac Tele CR 157 [101-244] 22.1 257 [142-465] 30.1 339 [182-633] 31.6 0.24 0.11 0.53 Loundoungou north 138 [79-241] 27.1 163 [111-238] 19.3 250 [166-378] 20.5 0.62 0.08 0.15 Mokabi FMU South 21 [5-87] 73.7 106 [58-196] 30.3 0.02↑

Great apes Great Nouabale-Ndoki NP 152 [103-226] 19.2 145 [104-204] 17.0 204 [147-283] 16.4 0.86 0.24 0.16 Pokola FMU north 482 [282-822] 26.2 661 [391-1119] 25.7 442 [308-635] 18.1 0.40 0.79 0.24 NL Landscape 197 [150-250] 14.3 295 [213-365] 14.6 312 [236-386] 8.9 0.04↑ 0.004↑ 0.72

Ndoki-Likouala large mammal survey 2016-2017

Table 6. Comparison of the abundance of great apes between the three survey periods. The p-values for the difference between each period are given in the last columns. P-values that are significant at p ≤ 0.05 are in red. Nest construction rate used for all great apes: 1.09 (SE 0.05) (Morgan et al., 2006). Nest degradation rate for gorillas: 149.1 (SE 8.32); chimpanzees: 143.8 (SE 7.86); and all great apes: 146.4 (SE 3.0) (Morgan et al., 2014). Great ape abundance 2006 2010-11 2016-17 p-value for significant diff 2006 -- 2006 -- 2010-11 -- Species Stratum N [95% CI] CV% N [95% CI] CV% N [95% CI] CV% 2010-11 2016-17 2016-17 Bailly north 2774 [1303-5905] 38.2 6955 [4033-11993] 27.5 8471 [5705-12578] 20.0 0.06 0.004↑ 0.55 Kabo FMU 4095 [1871-8960] 38.3 3160 [1127-8860] 51.7 4351 [3222-5876] 15.2 0.68 0.88 0.50 Lac Tele CR 3762 [2305-6139] 24.8 6055 [2964-12369] 36.7 7323 [3781-14184] 33.8 0.34 0.18 0.70 Loundoungou north 1884 [754-4704] 46.1 2675 [1510-4741] 29.2 4284 [2046-8972] 37.5 0.50 0.19 0.37

Gorilla Mokabi FMU South 113 [24-542] 82.6 713 [288-1762] 45.7 0.08 Nouabale-Ndoki NP 1492 [724-3073] 36.1 1400 [857-2287] 25.0 2354 [1564-3543] 20.7 0.89 0.24 0.11 Pokola FMU north 12586 [6657-23795] 31.6 18484 [9802-34859] 31.3 10795 [7331-15897] 19.5 0.40 0.69 0.21 NL Landscape 27384 [18554-37288] 18.3 38729 [24988-52953] 18.8 38292 [29947-50272] 13.2 0.18 0.11 0.96

Bailly north 1376 [730-2595] 31.7 2506 [1320-4756] 32.5 2332 [1474-3692] 23.3 0.22 0.17 0.86 Kabo FMU 612 [357-1050] 26.4 385 [181-821] 37.4 820 [502-1339] 25.0 0.29 0.43 0.08 Lac Tele CR 446 [203-981] 40.8 718 [430-1197] 26.0 642 [297-1390] 39.9 0.30 0.53 0.81 Loundoungou north 1613 [829-3140] 32.9 1203 [815-1774] 19.6 1962 [1216-3165] 23.9 0.48 0.62 0.15 Mokabi FMU South 72 [17-305] 74.9 329 [146-745] 40.9 0.08

Chimpanzee Nouabale-Ndoki NP 2547 [1485-4371] 26.6 2023 [1378-2968] 19.4 3086 [2059-4624] 20.4 0.50 0.56 0.15 Pokola FMU north 1059 [454-2469] 42.7 1394 [774-2509] 29.0 1009 [505-2018] 35.4 0.58 0.93 0.48 NL Landscape 7577 [5317-10490] 17.6 8147 [5818-10963] 15.6 10382 [8033-13028] 11.9 0.69 0.10 0.21

Bailly north 4237 [2593-6923] 24.4 9305 [5804-14916] 23.7 11300 [8487-15045] 14.4 0.04↑ 0.0003↑ 0.47 Kabo FMU 4587 [2582-8149] 27.8 4515 [1950-10455] 41.4 4917 [3792-6375] 13.1 0.97 0.82 0.84 Lac Tele CR 4155 [2652-6512] 22.7 6796 [3733-12372] 30.5 8976 [4785-16836] 32.0 0.25 0.11 0.54 Loundoungou north 3665 [2086-6439] 27.6 4311 [2907-6393] 19.9 6624 [4341-10107] 21.1 0.63 0.09 0.16 Mokabi FMU South 229 [55-958] 73.9 1169 [629-2171] 30.7 0.02↑ Great apes Great Nouabale-Ndoki NP 3885 [2592-5823] 19.9 3710 [2612-5269] 17.7 5213 [3709-7327] 17.1 0.86 0.26 0.18 Pokola FMU north 13590 [7903-23370] 26.7 18656 [10950-31786] 26.2 12475 [8579-18139] 18.8 0.40 0.80 0.25 NL Landscape 34008 [24341-45121] 15.6 46636 [36669-60461] 17.9 50350 [42529-59798] 10.4 0.20 0.03↑ 0.71

GREAT APE DISTRIBUTION IN THE LANDSCAPE Figures 7 and 8 show that the distribution of chimpanzees and gorillas has remained more or less stable since 2006. Gorillas were concentrated in the southern part of the landscape in Pokola, Bailly, Lac Télé, and Batanga where the canopy of the forest is often more open with thicker understory which gorillas prefer for nesting. Chimpanzees were concentrated more in the north of the landscape, mainly in NNNP and Loundoungou FMU, where the canopy is more closed and the understory more open.

Ndoki-Likouala large mammal survey 2016-2017

Figure 7. Distribution and density of gorillas in the Ndoki-Likouala landscape between 2006 and 2016-17.

Ndoki-Likouala large mammal survey 2016-2017

Figure 8. Distribution and density of chimpanzees in the Ndoki-Likouala landscape between 2006 and 2016-17.

ELEPHANT ABUNDANCE AND DISTRIBUTION The results for all original strata of the 2016-17 survey give a total of 10,550 elephants in the landscape (95% CI 8,705-12,566). The density of elephants was highest in NNNP with around 3000 individuals. The three CIB concessions of Pokola, Kabo, and Loundoungou were also very important for elephants; their distribution probably related to the combination of presence of yangas (figure 2a), the type of vegetation (mixed forest with dense understory), the permanent deep water of the Ndoki river, and areas of least human impact (Stokes et al., 2010).

Ndoki-Likouala large mammal survey 2016-2017

Table 7. Dung density, elephant density, and abundance of elephants in each stratum and the Ndoki-Likouala landscape for the 2016-17 survey. All dung density Elephant density Number of elephants Stratum %CV %CV Dung/km2 [95% CI] Elephants/km2 [95% CI] [95% CI] Bailly swamp 71 [32-155] 40.6 0.05 [0.02-0.12] 41.0 297 [135-656] Batanga 115 [51-263] 42.6 0.09 [0.04-0.20] 43.0 202 [88-463] Kabo FMU 898 [691-1166] 13.1 0.69 [0.52-0.92] 14.3 1915 [1444-2541] Lac Tele CR 82 [25-272] 65.2 0.06 [0.02-0.21] 65.4 267 [80-887] Loundoungou 159 [78-327] 36.7 0.12 [0.06-0.25] 37.2 371 [179-768] swamp Loundoungou FMU 335 [215-522] 22.2 0.26 [0.16-0.41] 22.9 1406 [892-2216] Mokabi FMU South 266 [110-639] 43.7 0.20 [0.08-0.49] 44.1 358 [148-866] Nouabalé-Ndoki NP 1013 [825-1245] 10.3 0.78 [0.62-0.98] 11.7 3174 [2517-4002] Pokola FMU 712 [401-1262] 29.1 0.55 [0.31-0.98] 29.6 2627 [1468-4702] NL landscape 408 [339-489] 9.1 0.31 [0.26-0.37] 9.2 10550 [8705-12566]

COMPARISON WITH PREVIOUS SURVEYS The density and number of elephants have remained stable since 2006, except for a loss of almost 1000 elephants in Loundoungou North between 2006 and 2010. There has been an increase of about 700 elephants in NNNP between 2010 and 2016. These results show that poaching pressure on elephants was reduced compared to other areas in the region that have experienced significant elephant losses. The increase in the elephant population in NNNP may be due to the arrival of elephants from elsewhere who seek the protection of the park. However, as the rest of the landscape in Congo outside NNNP has not experienced a decline in population (and the same is true of the contiguous Dzanga-Sangha complex in Central African Republic (N’Goran et al. 2016)), this suggests that the population is indeed stable. However, in neighboring Cameroon, the TNS lost elephants in the Lobeke NP (Nzooh Dongmo et al. 2016a) and in the TRIDOM area 75% of elephants were lost in five years (Nzooh Dongmo et al. 2016b).

Table 8. Comparison of elephant dung density between the three survey periods All elephant dung/km2 [95% CI] Elephants/km2 [95% CI] Stratum 2006 2010-11 2016-17 2006 2010-11 2016-17 Bailly north 599 [268-1341] 281 [172-459] 323 [214-486] 0.47 [0.20-1.09] 0.20 [0.11-0.36] 0.23 [0.15-0.35] Kabo FMU 1050 [706-1562] 1018 [584-1776] 904 [695-1174] 0.63 [0.40-0.98] 0.77 [0.43-1.38] 0.64 [0.48-0.85] Lac Tele CR 8 [2-29] 43 [18-103] 81 [24-269] 0.01 [0.00-0.03] 0.01 [0.00-0.07] 0.06 [0.02-0.19] Loundoungou north 453 [207-991] 193 [122-307] 150 [79-284] 0.33 [0.15-0.72] 0.07 [0.04-0.14] 0.11 [0.06-0.20] Mokabi FMU south 183 [77-432] 269 [112-648] 0.04 [0.02-0.13] 0.19 [0.08-0.46] Nouabalé-Ndoki NP 662 [508-862] 680 [555-832] 1020 [831-1253] 0.56 [0.40-0.77] 0.47 [0.36-0.61] 0.72 [0.57-0.91] Pokola FMU north 856 [517-1415] 683 [367-1270] 813 [450-1469] 0.70 [0.40-1.22] 0.46 [0.24-0.89] 0.58 [0.32-1.05] NL Landscape 540 [415-703] 499 [409-602] 0.42 [0.30-0.60] 0.35 [0.28-0.41] NL Landscape w/o Mokabi 441 [348-552] 0.30 [0.22-0.39]

Ndoki-Likouala large mammal survey 2016-2017

Table 9. Comparison of the number of elephants between the three survey periods. The p-values for the difference between each period are given in the last columns. P-values that are significant at p ≤ 0.05 are in red. P-values that are significant at p ≤ 0.10 are in bold. N elephants [95% CI] p-values

2006 2010- 2016- 2006- 2006 - 2010-11 - Stratum 2006 %CV 2010-11 11 %CV 2016-17 17 %CV 2010-11 2016-17 2016-17 Bailly north 2694 [1145-6337] 43.6 1136 [621-2080] 30.7 1328 [870-2027] 21.1 0.20 0.26 0.67 Kabo FMU 1734 [1109-2710] 20.6 2135 [1187-3840] 28.4 1780 [1342-2361] 15.1 0.57 0.92 0.59 Lac Tele CR 35 [10-125] 66.0 58 [12-292] 92.9 243 [73-808] 65.4 0.70 0.20 0.27 Loundoungou north 1404 [644-3058] 37.1 307 [162-583] 32.9 451 [236-861] 31.5 0.05↓ 0.09↓ 0.42 Mokabi FMU south 78 [27-228] 44.1 335 [139-811] 43.4 0.09↑ Nouabalé-Ndoki NP 2261 [1637-3122] 15.8 1902 [1452-2491] 13.6 2950 [2340-3720] 12.8 0.42 0.17 0.02↑ Pokola FMU north 3161 [1816-5503] 27.2 2090 [1095-3988] 32.0 2601 [1428-4738] 30.4 0.33 0.63 0.62 NL Landscape 11366 [8228-16384] 17.4 9529 [7677-11225] 8.9 NL Landscape w/o Mokabi 11288 [8201-16156] 7628 [5690-10028] 14.3 9194 [7538-10414] 0.10 0.33 0.25

Figure 9. Comparison of the number of elephants by stratum per survey year 7000

6000

5000

4000 2016 3000 2010-11

2000 2016-17 Nelephants 1000

0 Bailly north Kabo FMU Lac Tele CR Loundoungou Mokabi FMU Nouabale-Ndoki Pokola FMU north south NP north

ELEPHANT DISTRIBUTION IN THE LANDSCAPE With the exception of a loss of around 1,000 elephants in Loundoungou between 2006 and 2010, elephant distribution has been remarkably stable in the 10 years since the first survey. Elephants were most abundant in NNNP, and continue to use the corridor of yangas and baïs west of the Ndoki River that extends from the Kabo FMU to the south of the Pokola FMU.

Ndoki-Likouala large mammal survey 2016-2017

Figure 10. Distribution and density of elephants across the Ndoki-Likouala landscape across three survey periods

UNGULATE RELATIVE ABUNDANCE AND DISTRIBUTION Ungulate dung is difficult to identify at the species level, and the droppings of the young of the largest ungulates can be confused with small ungulates. So we used three size classes of ungulates for recording dung:  U1: The small blue duiker Philantomba monticola, and infants and/or juveniles of medium-sized ungulates  U2: Medium-sized duikers Cephalophus callipygus, C. leucogaster, C. nigrifrons, and C. dorsalis; the water chevrotain Hyemoschus aquaticus, and young yellow-backed duikers, sitatunga, and bongo  U3: Large ungulates Cephalophus silvicultor, the sitatunga Tragelaphus spekii, and the bongo Tragelaphus euryceros

Buffalo (Syncerus caffer nanus) and Suidae (Red river hog (Potamochoerus porcus) and Giant forest hog (Hylochoerus meinertzhageni)) dung are distinct and are recorded separately. Normally bongo dung is also distinct, but for these analyzes it has been combined with the category U3.

Ndoki-Likouala large mammal survey 2016-2017

The results of the three classes were similar; therefore we combined all the duiker dung in one analysis to have better precision for the comparison between surveys. Results show that the highest dung density for ungulates was found outside of the park in the southern part of the Mokabi concession, followed by Loundoungou FMU. These densities were two times greater than that found in the park. Ungulate density was low in swampy strata, perhaps due to fast dung degradation or because within this habitat only three species of ungulate Sitatunga (Tragelaphus spekei), water chevrotain (Hyemoschus aquaticus) and black-fronted duiker (Cephalophus nigrifrons) are highly adapted to swamp living. Kabo FMU had very low densities of ungulates, almost a third of that in NNNP.

Table 10. Dung density of all ungulates (small (U1), medium (U2), and large (U3)) in each stratum as well as the Ndoki- Likouala landscape for the 2016-17 survey. All ungulates, including bongos (but not red river hogs, giant forest hogs, or buffalo), were analyzed together. N km N dung N dung N dung Total dung/ dung/km2 Strata 2016-17 transects transect U1 U2 U3 dung km [95% CI] %CV Bailly swamp 41 81.3 40 44 20 104 1.3 344 [145-816] 44.9 Batanga 41 81.0 19 342 19 380 4.7 1209 [745-1963] 24.3 Kabo FMU 51 101.6 70 388 185 643 6.3 594 [334-1057] 29.1 Lac Tele CR 43 85.8 8 148 50 206 2.4 485 [280-842] 27.7 Loundoungou swamp 35 69.8 39 58 36 133 1.9 485 [280-842] 27.7 Loundoungou FMU 34 68.0 202 523 105 830 12.2 3160 [2438-4097] 12.9 Mokabi FMU South 18 36.0 87 365 53 505 14.0 3611 [2730-4777] 13.4 Nouabalé-Ndoki NP 45 90.0 110 385 94 589 6.5 1676 [1306-2151] 12.5 Pokola FMU 45 90.0 123 377 145 645 7.2 1838 [1399-2417] 13.7 Total Landscape 353 703.5 698 2630 707 4035 5.7 1512 [1276-1743] 7.8

COMPARISON WITH PREVIOUS SURVEYS The density of the dung piles of small, medium and large ungulates was variable between the different survey years. The 2010-11 survey showed a decrease in dung density compared to 2006 and 2016-17. This result could be caused by the higher level of rainfall in 2010 (figure 3) which indicates that perhaps the detection and/or decay rate of dung in 2010-11 was affected by the high amount of rain. Taking into account the difference between 2006 and 2016-17, the ungulate population was stable in all strata, with a significant increase in Bailly and Lac Télé Community Reserve (table 11).

Table 11. Comparison of ungulate dung density between the three survey periods. P-values that are significant at p ≤ 0.05 are in red. P-values that are significant at p ≤ 0.10 are in bold. Ungulate dung/km2 [95% CI] p-values 2006 2010-11 2016-17 2006- 2006 - 2010-11 - Stratum 2006 2010-11 2016-17 %CV %CV %CV 2010-11 2016-17 2016-17 Bailly north 746 [470-1182] 22.7 828 [478-1433] 27.6 1467 [983-2188] 20.1 0.77 0.03↑ 0.09↑ Kabo FMU 1218 [804-1846] 20.0 638 [362-1125] 27.4 1488 [1142-1939] 13.3 0.05↓ 0.39 0.001↑ Lac Tele CR 204 [107-387] 32.8 194 [110-342] 29.0 588 [331-1045] 29.1 0.91 0.04↑ 0.03↑ Loundoungou north 2714 [1895-3887] 17.2 790 [555-1127] 17.8 2245 [1508-3342] 19.6 0.00↓ 0.46 0.00↑ Mokabi FMU south 3569 [2712-4696] 12.5 3544 [2680-4687] 13.4 0.97 Nouabale-Ndoki NP 1632 [1261-2111] 12.7 927 [686-1252] 15.1 1615 [1259-2072] 12.4 0.005↓ 0.95 0.00↑ Pokola FMU north 1323 [824-2125] 23.1 765 [509-1149] 19.9 2022 [1543-2651] 13.5 0.10 0.09↑ 0.00↑ Total Landscape 1404 [1207-1595] 7.4 701 [562-838]* 10.1 1687 [1447-1934] 7.4 0.005↓ 0.08↑ 0.00↑ 24

Ndoki-Likouala large mammal survey 2016-2017

*The landscape densities include Mokabi in 2006 and 2016-17, but not for 2010.

Figure 11. Comparison of ungulate dung density in each stratum between 2006 and 2016-17. Dung density for the landscape in 2010-11 does not include a density for Mokabi. Given the high density at Mokabi, the overall density of 2010-11 was probably underestimated. All ungulate dung density 5000

4000

3000 2006 2010-11 2000

Dung/km2 2016-17

1000

0 Bailly north Kabo FMU Lac Tele CR Loundoungou Mokabi FMU Nouabale-Ndoki Pokola FMU Total Landscape north south NP north

UNGULATE DISTRIBUTION IN THE LANDSCAPE The southern part of Mokabi FMU has the highest density of ungulates of all strata. This phenomenon was also evident in 2006. Despite strong hunting pressure in this area, especially near the border with CAR (figures 14 and 15), the presence of ungulates remains high. Forest type here is –anecdotally- very different from other forests of the region, being much drier (very few streams between the major rivers) and with a distinct vegetation type (Sylvie Gourlet-Fleury, pers. comm).

The Loundoungou FMU, especially on the edge of the swamp, was also very important for ungulates (figure 12). In contrast, swampy areas have low densities of ungulates. The center of Kabo FMU was also rich in ungulates, potentially due to the concentration of yangas and baïs in the area of Bonio.

Ndoki-Likouala large mammal survey 2016-2017

Figure 12. Comparison of the distribution and density of ungulate dung during three survey periods

HUMAN SIGN ABUNDANCE AND DISTRIBUTION Signs of human presence have been classified according to their threat to wildlife in three categories: Human Presence not related to hunting (Level 1), Human Presence that may be related to hunting (Level 2), and Hunting Signs or other threats (Level 3).

Ndoki-Likouala large mammal survey 2016-2017

Table 12. Classification of different types of human sings found on transects Level 1 Level 2 Level 3 Human signs not related to hunting Potential threats Hunting signs or other threats NTFP harvesting Machete cuts Hunting camp Forestry activities (Log bays, Trail Gun shot heard prospection transects, cut trees, Footprint or passage Shotgun cartridge logging truck, quarry for laterite) Camp fire Snare (metal, nylon, etc.) Agriculture (clearing, brush fire) Fishing or gathering camp Mine (diamond, gold) Wooden canoe fabrication Direct observation of hunter Motor noise Other activities linked to hunting or illegal collecting of animals

The majority of the signs observed on transects in 2016-17 were tracks and machete cuts (table 13). Direct hunting signs were rarer on transects. New forestry activity was visible in the north-east of Kabo FMU, where forest prospection has been carried out since 2014 and active exploitation started in 2016 (figure 13). Prospection transects and roads have opened the area to poachers, who are beginning to enter the park from these roads. Although poaching signs have not been detected south of the park on transects, poaching incidences in the Goualougo triangle have been more common since 2016, with an elephant killed 500 m from the Goualougo research camp in 2017.

During the 2016-17 survey 26 elephant carcasses were found. Only two carcasses were observed on transects, one with signs of poaching, and the other where the cause of death remained unknown. 24 carcasses were found on travel recces (16 poached, 6 unknown cause, and 2 presumed natural deaths). Elephants killed by poachers were all found in the Kabo and Pokola concessions (figure 13).

Table 13. Number of human signs in 2016-17 of three different levels of threat detected on transects Level 1 Level 2 Level 3 Human signs not related to Potential Hunting Total Sign hunting threats signs Camp 21 21 Snare 20 20 Gunshot heard 16 16 Shotgun cartridge 14 14 Animal collection 12 12 Elephant carcass (poached) 1 1 Human trail 351 351 Machete cut 153 153 Fire 5 5 Fishing 3 3 Footprint 1 1 Direct observation 1 1 Forestry 92 92 NTFP 20 20 Canoe fabrication 4 4 Other 3 3 Brush fire 2 2 Agriculture 2 2 Total 123 514 83 721

Ndoki-Likouala large mammal survey 2016-2017

In 2016-17, Mokabi had the highest encounter rate of human signs with 2.83 signs per kilometer traveled on transects. However, when looking only at hunting sign, Loundoungou swamp (primarily near Mokengui), Kabo FMU, and then Mokabi had the highest encounter rates of hunting (table 14). NNNP had the lowest encounter rate of all strata. The only sign of hunting detected on transects in the park was a cable snare found in the north of the park near Bonye baï. Undoubtedly other illegal hunting had taken place in the park off transects, but none was found on travel or guided recces in the park. Hunting signs found on recces confirmed the patterns seen on transects, but also indicated much higher pressure on the east bank of the Sangha river between Kabo and Pokola, and south to Pikounda. The western half of the Mokabi south strata also had many more hunting signs observed on recces than on transects. This is to be expected, as recces can follow trails, which are also more likely to be used by humans to travel through the forest.

Table 14. Encounter rate of all human sign and hunting sign in the 2016-17 strata N Hunting km N human Signs/km [95% hunting signs/km [95% Strata 2016-17 N transects transect signs (all) IC] SE signs IC] SE Bailly swamp 41.0 81.3 61 0.76 [0.50-1.03] 0.14 6 0.08 [0.00-0.17] 0.04 Batanga 41.0 81.0 91 1.17 [0.84-1.50] 0.17 10 0.12 [0.02-0.23] 0.05 Kabo FMU 51.0 101.6 127 1.25 [0.95-1.56] 0.16 22 0.23 [0.10-0.36] 0.07 Lac Tele CR 43.0 85.8 47 0.55 [0.33-0.77] 0.11 7 0.08 [0.00-0.17] 0.04 Loundoungou 35.0 69.8 76 1.12 [0.76-1.48] 0.18 16 0.24 [0.07-0.40] 0.08 swamp Loundoungou FMU 34.0 68.0 78 1.12 [0.77-1.47] 0.18 6 0.09 [0.01-0.19] 0.05 Mokabi FMU South 18.0 36.0 102 2.83 [2.06-3.61] 0.40 8 0.22 [0.00-0.44] 0.11 Nouabalé-Ndoki NP 45.0 90.0 17 0.19 [0.06-0.32] 0.06 1 0.01 [0.00-0.04] 0.02 Pokola FMU 45.0 90.0 121 1.34 [1.01-1.68] 0.17 7 0.08 [0.00-0.16] 0.04 NL landscape 353.0 703.5 720 1.03 [0.93-1.14] 0.05 83 0.12 [0.08-0.16] 0.02

HUMAN SIGN DISTRIBUTION IN THE LANDSCAPE The southwestern Mokabi FMU was a hotspot for threats, including illegal diamond mining and incursions by CAR poachers. The riparian population of the northeastern Loundoungou FMU probably has a strong impact on wildlife, as well as the villages of Mokengui and Mboua at the northern limit of Lac Télé CR. The towns and villages on the banks of the Sangha (Kabo, Ouesso, Pokola, Pikounda) have a presence that extends inside Pokola and Kabo FMUs, and into the Bailly swamp.

The majority of signs were machete cuts and human trails, which if present in protected areas or far from villages are likely an indication of hunting. The Level 2 signs present in the western half of the Mokabi South stratum were thus very likely to be indicators of hunting (figure 13). While NNNP seems well-protected, the presence of human sign related to forestry activities to the east of the Goualougo Triangle on the southern limit of the park has increased poaching incursions into the park, becoming more intense after the 2016 survey. Poached elephant carcasses were found primarily in Kabo and Pokola concessions.

Ndoki-Likouala large mammal survey 2016-2017

Figure 13. Comparison of the relative abundance of human activity signs of the three different threat levels. The map on the right also shows elephant carcasses found on transects and recces during the survey. Carcasses identified with signs of poaching are in red.

Ndoki-Likouala large mammal survey 2016-2017

COMPARISON WITH PREVIOUS SURVEYS Compared with 2006 and 2010-11, no strata had a significant difference in the human sign encounter rate with the exception of a decrease in human signs in Pokola North in 2016 (table 15, figure 14).

Table 15. Comparison of human sign encounter rates between the three survey periods for common strata Encounter rate: All human signs/km p-values 2006- 2006 - 2010-11 - Common strata 2006 2010-11 2016-17 2010-11 2016-17 2016-17 Bailly north 0.77 [0.42-1.12] 0.73 [0.45-1.00] 0.63 [0.40-0.85] 0.90 0.59 0.70 Kabo FMU 1.47 [0.85-2.08] 0.93 [0.46-1.40] 1.25 [0.95-1.56] 0.73 0.73 0.57 Lac Tele CR 0.89 [0.61-1.16] 0.64 [0.41-0.87] 0.55 [0.33-0.77] 0.40 0.23 0.68 Loundoungou north 1.20 [0.69-1.71] 1.71 [1.33-2.09] 1.48 [1.02-1.93] 0.42 0.61 0.68 Mokabi FMU South 2.50 [1.52-3.48] 2.83 [2.06-3.61] 0.79 Nouabalé-Ndoki NP 0.13 [0-0.28] 0.14 [0.03-0.24] 0.19 [0.06-0.32] 0.92 0.74 0.73 Pokola FMU north 2.21 [1.58-2.85] 1.95 [1.35-2.55] 1.07 [0.74-1.39] 0.75 0.03↓ 0.07↓ NL landscape 1.15 [0.98-1.32] 0.96 [0.84-1.07] 0.28 NL landscape w/o Mokabi 1.06 [0.89-1.23] 0.75 [0.63-0.87] 0.82 [0.71-0.93] 0.47 0.15 0.52

Figure 14. Comparison of human sign encounter rates between the three survey periods for common strata

NNNP was still the most intact area of the landscape. However, there were incidences of poaching, especially elephants, in the park that were not detected during the survey. Since 2006, threats have approached the park from the east and south, especially with active logging in Kabo and Loundoungou. These forestry activities, in principle, do not pose a direct threat to wildlife, but in practice they increase accessibility for poachers to the borders of the park.

Another area that has remained more or less intact for 10 years (the darker green areas in figure 15) was the zone from the middle of Lake Tele CR, across the Bailly swamp, to southern Loundoungou and Pokola FMUs. This swampy area contains important populations of gorillas.

Ndoki-Likouala large mammal survey 2016-2017

Figure 15. Comparison of encounter rates and distribution of human signs between the three survey periods. Activity levels 2 (potential threats) and 3 (hunting signs) are combined in this figure.

OTHER SPECIES DISTRIBUTION RED RIVER HOG (POTAMOCHOERUS PORCUS) AND GIANT FOREST HOG (HYLOCHOERUS MEINERTZHAGENI)

The two species in the Suidae family are sometimes difficult to distinguish from their tracks. Photo trap data show that the Giant Forest Hog is generally less abundant than the Red River Hog, but it is likely that some traces attributed to Red River Hog are, in fact, that of the Giant Forest Hog. For this reason, both species were counted together for this study.

The results show that the southern part of the Mokabi FMU was the richest in Suidae with an encounter rate of 0.50 dung/km of transect (table 15). This abundance has remained stable for the past 10 years (figure 16). Within the common strata, Loundoungou North and Pokola North showed a decline in the Suidae population between 2006 and 2010, but in the last five years the population has remained stable.

Ndoki-Likouala large mammal survey 2016-2017

Table 16. Encounter rate of Suidae dung recorded during the 2016-17 survey N dung per Encounter rate dung/km Strata 2016-17 stratum [95% CI] SE Bailly swamp 16 0.20 [0.07-0.32] 0.07 Batanga 10 0.13 [0.04-0.22] 0.05 Kabo FMU 22 0.22 [0.08-0.35] 0.07 Lac Tele CR 7 0.08 [0.02-0.15] 0.03 Loundoungou 6 0.09 [0.00-0.19] 0.05 swamp Loundoungou FMU 22 0.31 [0.07-0.56] 0.12 Mokabi South 18 0.50 [0.11-0.89] 0.20 Nouabalé-Ndoki NP 16 0.18 [0.02-0.34] 0.08 Pokola FMU 12 0.13 [0.04-0.22] 0.05 NL landscape 129 0.18 [0.14-0.23] 0.03

Figure 16. Comparison of Suidae dung encounter rates in different strata common between the three surveys

Ndoki-Likouala large mammal survey 2016-2017

Figure 17. Comparison of the distribution of Suidae during the three survey periods in the Ndoki-Likouala landscape. Interpolation maps are of dung encounter rate.

AFRICAN GREY PARROT (PSITTACUS ERITHACUS)

African Grey Parrots are under immense pressure from wildlife trackers, who trap large numbers of birds to sell for the pet trade (Annorbah et al. 2016, Birdlife International 2017, Martin et al. 2015). Until now, these populations have never been monitored in the Ndoki-Likouala landscape. Given that this species is at risk of extinction from commercial trade, we collected encounter rates of parrot calls or direct observations during transects. Given that the time required to complete a transect varied with the terrain, and the fact that parrots can cover great distances quickly, we calculated the encounter rate per hour of observation instead of km of transect traveled (Marsden et al. 2015). 318 groups or individual parrots were seen or heard during 2440 hours of observation.

Parrots were most frequently encountered Kabo FMU, followed by the park and Mokabi FMU. The reason for the high concentration of parrots in Kabo may be related to the concentration of yangas, and the proximity of baïs on the other side of the Sangha River in Cameroon. Parrots appear to be scarce in swamps.

Ndoki-Likouala large mammal survey 2016-2017

Figure 18. Encounter rate (observations per hour) of African Grey parrots on transects African Grey Parrot (Psitaccus erithacus) 0.35 0.3 0.25 0.2 0.15

Observations /hr Observations 0.1 0.05 0

Figure 19. Distribution and relative abundance of African Grey Parrots (encounter rate of vocalizations and direct observations)

Ndoki-Likouala large mammal survey 2016-2017

MONKEYS The encounter rate for all species of monkeys was based on direct observations or vocalizations of groups of monkeys on transects. The most common species was the putty-nosed monkey (Cercopithecus nictitans). For all monkey species combined, NNNP had the highest encounter rate of all strata, with 1.81 groups of monkeys per km of transect in the park. After the putty-nosed monkey, the most common species were the crowned guenon (C. pogonias) and the gray-cheeked mangabey (Lophocebus albigena).

Table 17. Encounter rate of monkey observations per km of transect walked in each stratum

Cercocebus Lophocebus Cercopithecus C. C. C. Colobus Piliocolobus All Strata agilis albigena cephus neglectus nictitans pogonias guereza oustaleti monkeys Bailly 0.15 0.01 0.00 0.02 0.91 0.17 0.00 0.00 1.27 Batanga 0.02 0.05 0.01 0.01 0.73 0.11 0.00 0.04 0.98 Lac Télé CR 0.08 0.07 0.00 0.00 0.98 0.19 0.00 0.02 1.34 Lound swamp 0.13 0.01 0.00 0.01 1.21 0.10 0.01 0.00 1.53 NNNP 0.06 0.51 0.00 0.00 1.08 0.11 0.04 0.00 1.81 Kabo FMU 0.01 0.25 0.00 0.00 0.59 0.08 0.02 0.00 0.95 Loundoungou FMU 0.10 0.29 0.01 0.00 1.22 0.01 0.00 0.00 1.63 Mokabi FMU south 0.00 0.14 0.00 0.00 0.72 0.03 0.00 0.00 0.92 Pokola FMU 0.02 0.17 0.00 0.01 0.48 0.07 0.00 0.00 0.74 Mean ER 0.06 0.17 0.00 0.01 0.87 0.10 0.01 0.01 1.24

Monkeys appear to be susceptible to rifle hunting, and were rare or absent around the centers of Pokola, Kabo, and Ouesso (figure 20). This phenomenon was particularly visible for C. nictitans distribution. This species is normally very common, found in abundance throughout the landscape, but was almost absent around these towns. Monkeys are also adapted to stop vocalizing in the presence of hunters (Croes et al. 2007), which may have reduced their detectability on transects around towns where gun hunting may be more common.

Ndoki-Likouala large mammal survey 2016-2017

Figure 20. Distribution and relative abundance of monkeys. Species shown: Cercocebus agilis, Lophocebus albigena, Cercopithecus cephus, Cercopithecus neglectus, Cercopithecus nictitans, Cercopithecus pogonias, Colobus guereza, and Piliocolobus oustaleti.

Ndoki-Likouala large mammal survey 2016-2017

FOREST BUFFALO (SYNCERUS CAFFER NANUS)

Too few signs of buffalo were encountered on transects to do any meaningful encounter rates or comparison between years. Consistent with their preference for open areas where grasses can be found, buffalo tend to be encountered more frequently in areas with baïs or yangas (Kabo and Pokola FMUs) or in the flooded savannas of the Lac Tele landscape (figure 21).

Table 18. Number of signs of buffalo encountered on transects in the three survey periods N all buffalo signs N buffalo dung only Strata 2016 2010-11 2016-17 2016 2010-11 2016-17 Bailly North 0 3 1 0 3 1 Kabo FMU 4 2 4 2 2 4 Lac Tele CR 13 5 4 0 0 1 Loundoungou North 1 5 0 1 4 0 Mokabi FMU South 0 na 0 0 na 0 NNNP 1 1 2 1 0 2 Pokola North 12 7 4 10 7 4 NL Landscape 31 23 15 14 16 12

Figure 21. Distribution of all signs of buffalo (dung, tracks, trails, or direct observations) encountered on transects

Ndoki-Likouala large mammal survey 2016-2017

DISCUSSION AND RECOMMENDATIONS

The results of this study give us something sadly uncommon in conservation stories in Central Africa: good news. The Ndoki-Likouala landscape continues to be home to large populations of large mammals, and for 10 years the populations of flagship species have been stable, or even increasing in some strata. For large mammals with important home ranges such as elephants, the data clearly demonstrated the benefits of the landscape management approach.

ELEPHANTS Elephant poaching remains a real threat across the landscape. A total of 26 elephant carcasses were discovered during the censuses, of which 17 were attributed to poaching.

In view of the catastrophic loss of Central African forest elephant populations (Maisels et al., 2013), the Ndoki-Likouala landscape is not immune to poaching pressure for the ivory trade. The northern Loundoungou FMU and adjacent swamps experienced a loss of around 1000 elephants (p = 0.05) between 2006 and 2010. However, the elephant population in the rest of the landscape remained stable during this period. The 2016-17 survey shows that the population remained unchanged (no significant differences at a level of p ≤ 0.05), except for a significant increase in elephant abundance in NNNP (p = 0.02). The total elephant population for the surveyed landscape in 2016-17 was between 8,705-12,566 individuals (95% CI). These animals were concentrated in the park and in the forest concessions managed by CIB under FSC certification standards. These standards require best management practices for the protection of flora and fauna in logged areas. The wildlife protection and management programs implemented in the Kabo and Pokola forest concessions have contributed to the successful conservation of substantial elephant populations in this area.

Unfortunately carcasses of elephants killed by poachers continue to be discovered every month in the landscape by teams from the Anti-Poaching Unit and researchers in the forest. How to reconcile these losses with the idea that the population remains stable? Three elements are needed to answer this question. The first is a reliable estimate of the number of elephants killed each year. The carcasses found in the forest and the tusks seized represent only a part of the animals killed. We need to develop a methodology to estimate the true rate of poaching for the landscape.

The second is to model population dynamics using biological factors (reproduction rate, natural mortality, age of first reproduction, etc.) from long-term research studies on forest elephants (ex. Turkalo et al. 2017). Such modeling can be used to show how the elephant population in the Ndoki- Likouala landscape changes with different levels of poaching.

The third method that might lead to a better understanding of population dynamics is to track the movements of elephants in and out of the park. If the true number of elephants lost to poaching is higher, and the natural growth of the population cannot explain its stability, it is possible that mortality losses are offset by the immigration of elephants from elsewhere such as Cameroon (see recent reports from Nzooh Dongmo 2016a,b, N’Goran et al. 2016), or Ngombé FMU for example The growth of the population in NNNP could be explained by the compression of elephants into this well protected refuge. To know if this is the case, the use of GPS collars on elephants in the landscape and nearby landscapes can give an important indication of elephant movements in response to hunting pressure and the availability of food in the environment.

Ndoki-Likouala large mammal survey 2016-2017

GREAT APES Evidence of poaching of great apes was minimal in the Ndoki-Likouala landscape, and thus, as in 2006, the type of forest remains one of the most important factors in the distribution of gorillas and chimpanzees. Gorillas were at their highest density in the Raffia forests in Batanga and in the swamp forests of the Lac Télé Community Reserve. But the highest number of gorillas was found in the Pokola FMU (9,900 gorillas [95% CI 6,082-16,181]) and Loundoungou FMU (i.e. 9,368 gorillas [95% IC 6,474- 13,556], especially near the Bailly swamp.

NNNP was the most important stratum for chimpanzees, with around 3,000 chimpanzees (95% CI 2,015- 4,521) due to its abundance of monodominant Gilbertiodendron dewevrei forest and mixed open understory forest, habitats preferred by chimpanzees (Morgan et al., 2006). Apart from the large number of gorillas, Loundoungou FMU also has high densities of chimpanzees, making it the most important stratum for great apes in terms of numbers of individuals.

UNGULATES All small, medium, and large ungulates (including all duiker species plus sitatunga and bongo) were analyzed together. A big surprise was the high abundance of ungulates in the southern Mokabi area, despite the very high encounter rate of human signs that has persisted since 2006.

The density of ungulates across the landscape as a whole has remained largely stable between the two surveys of 2006 and 2016-17. The variations in the densities in 2010-11 can be explained either by the impact of the different amounts of rain during the surveys, which could have had an impact on the degradation or visibility of the dung, or by the difference of stratification (such as the case of Bailly North).

HUMAN IMPACT The encounter rate of human signs did not change significantly between the three surveys in the different strata. NNNP remains a refuge for animals, with very few human signs inside. Nevertheless, human activities surround the park in all directions, especially in the south with new logging roads in Kabo FMU giving poachers easier access to the park.

Mokabi has the highest intensity of human signs for the last 10 years. These human activities encroach on the northern limit of NNNP. The human encounter rate was twice as high as any other area, and was an order of magnitude higher than in the park.

Based on the results presented in this report, we recommend that:

 In order to maintain the integrity of the park, it is essential to at least maintain the same level of eco-guard patrols in the park and its periphery. All borders are vulnerable to human activities. Although the pressure may be low compared to other landscapes, continued vigilance is important to ensure that the landscape remains a refuge from increased criminality in poaching.  Further studies on elephant movements are needed to better understand nutritional requirements, response to threats, and other factors that determine the seasonal movement of elephants. An understanding of the factors that cause them to leave protected areas, or to seek refuge, can help guide protection activities.

Ndoki-Likouala large mammal survey 2016-2017

 SMART data needs to be combined and analyzed in such a way that it allows a better estimate of the true elephant poaching rate, and that these data are used in a model that can explain the stability of the population given the existing poaching in the last 10 years.  Every effort should be made to control access to the active logging area in the Kabo FMU from the new forestry roads.  If possible, increased protection activities in the Pokola and Loundoungou FMUs are necessary to protect important populations of large mammals in these concessions.

ACKNOWLEDGEMENTS

The success of this third large mammal survey in Ndoki-Likouala is to the credit of several people, especially the field teams who have faced difficult conditions during long missions in the forest. Team leaders Bola Madzoké, Christian Ndzai, and Venant Bomomo served as mentors to new assistants, sharing their knowledge and passion for biodiversity and nature, and passing on their skills. I had the pleasure of counting on a very motivated team, dedicated to completing this survey, including the new team leaders, Onesi Samba, Frelcia Bambi, Ferré Mboussa, and Joules Elari, as well as the assistant researchers Adrich Mouamana, Vigny Mpambouri, Phael Malonga, Jess Bahamboula, Arel Mapembi, Espoir Magema, Christ Mougani, Aristide Mouele, and Gaston Abea. Compass bearers, guides, and porters contributed immensely to the success of this study.

The technical and practical training of this team was made possible thanks to the trainers who dedicated their time, expertise, and passion: Dr. Boo Maisels, Clement Inkamba-Nkulu, Fortuné Iyenguet, as well as the experienced team leaders, Christian Ndzai, Bola Madzoké, Venant Bomomo, and Franck Kiminou. Dr. Alain Ondzie provided training on the collection of dung samples that was much appreciated.

I would like to thank the WCS Brazzaville team, particularly Amy Pokempner, Mark Gately, and Emma Stokes; The WCS Nouabalé-Ndoki team, including Richard Malonga, Rebekah Kokalis, Kyle Winney, Willy Safou Makaya, Igor Eyalola, Tomo Nishihara, Cisquet Keibou Opepa, Rolland Abegouo, Eric Arnhem, and Nick Radford; the WCS Lac-Télé team, including Ben Evans, Max Mviri, and Terence Moussavou; Domingos Dos-Santos, Jonas Moussongo, and the PROGEPP / CIB / Kabo team for logistical and administrative support. Drs Samantha Strindberg, Boo Maisels, Emma Stokes, and Eric Arnhem provided important advice on the design, analysis and interpretation of the data, for which I am very grateful.

The collaboration of the Ministry of Forest Economy was essential for conducting this study. I would like to thank the CNIAF agents who participated in the preliminary training sessions and analyses: Jean- Claude Kombo, Charles Epari, Lena Ofinguini, and Karel Mengué.

I would also like to thank the Conservator of the Nouabalé-Ndoki National Park, Marcel Ngangoue and the Conservator of the Lac Télé Community Reserve, Max Mviri, our government partners who have supported this program.

Ndoki-Likouala large mammal survey 2016-2017

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