Camera Trap Monitoring for Wildlife Density Estimation with the REST Model: A Handbook Focusing on Rainforest Mammals

This handbook is a product of an international joint research initiative between Cameroon and Japan funded by JST/JICA SATREPS (JPMJSA1702) and JSPS KAKENHI (JP18K14803, JP 20KK0015, JP21K15173).Earlier handbook version (Hongo et al. 2021).1. Introduction [3]Why Camera Traps, and Why Population Density? [3]Using the Detection Rate is “a Risky Business” [4]Estimating the Population Density of the “Unmarked” Animals [5]The REST model [6]2. The REST model: A Brief Explanation [7]Formula [7]Assumptions [7]Limitations [9]Suitable and Unsuitable Situations for REST [9]3. Development of REST Monitoring Protocols [11]Required Specifications of Camera Traps [11]Camera Placement Design [12]Layout of Camera Stations [15]4. Carrying Out the Monitoring [19]Materials [19]Configuration of Camera Setting [19]Setting of Camera Stations in the Field [20]5. Data Analysis [23]Species Identification [23]Judgement on whether the target species passed through the focal area [24]Measurement of staying time in each passage [24]Acquisition of time data for each passage [24]Data shaping and cleaning [26]Statistical analysis to estimate density [26]6. Perspectives [27]References [28

Seasonality in daily movement patterns of mandrills revealed by combining direct tracking and camera traps

野生マンドリルの移動パターンを解明 --直接追跡法と自動撮影カメラ法を組み合わせて説得力のある結論を得る--. 京都大学プレスリリース. 2021-11-26.Movement is a fundamental characteristic of animals, but challenging to measure noninvasively. Noninvasive methods for measuring travel have different weaknesses, so multiple techniques need to be applied multiple techniques for reliable inferences. We used two methods, direct tracking and camera trapping, to examine the variation in time and seasonal differences in movement rates of mandrills (Mandrillus sphinx), an elusive primate that lives in large groups in central Africa. In a 400-km2 rainforest area in Moukalaba-Doudou National Park, Gabon, we tracked unidentified groups 46 times from 2009 to 2013. We systematically placed 157 terrestrial camera traps in the same area from 2012 to 2014 and recorded groups 309 times. Generalized additive mixed models (GAMMs) of the tracking data indicated that the group travel speed varied with time and season. In the fruiting season, the movement rate fluctuated with time in a bimodal pattern, whereas in the nonfruiting season, it increased monotonously with time. The predicted day range was longer in the fruiting season (6.98 km) than in the nonfruiting season (6.06 km). These seasonal differences suggest responses to changes in food resources and temperature. Camera-trap detection rates showed similar temporal and seasonal patterns to the tracking data, allowing us to generalize our findings to the population level. Moreover, cameras never detected mandrills at night, and we observed that they slept high in trees and hardly moved until the next morning, all suggesting their strict avoidance of nighttime movement. This study demonstrated the significance of the multiple-method approach in drawing robust conclusions on temporal patterns of animal movement.Le mouvement est une caractéristique fondamentale des animaux, mais il est difficile de le mesurer de manière non invasive. Les méthodes non invasives de mesure des déplacements présentent des faiblesses différentes, de sorte que nous devons appliquer plusieurs techniques à un même sujet pour obtenir des déductions fiables. Nous avons utilisé deux méthodes, le suivi direct et le piégeage photographique, pour examiner les variations temporelles et la différence saisonnière des taux de déplacement des mandrills (Mandrillus sphinx), un primate insaisissable vivant en grands groupes. Dans une zone de forêt tropicale humide de 400 km2 du parc national de Moukalaba-Doudou au Gabon, nous avons suivi des groupes non identifiés 46 fois entre 2009 et 2013. Dans la même zone, nous avons systématiquement placé 157 pièges photographiques terrestres de 2012 à 2014 et enregistré des groupes 309 fois. Les modèles mixtes additifs généralisés (GAMM) des données de suivi ont indiqué que la vitesse de déplacement des groupes variait en fonction du temps et des saison. Pendant la saison de fructification, la vitesse de déplacement fluctuait dans le temps selon un schéma bimodal, tandis que pendant la saison de non-fructification, elle augmentait de façon monotone avec le temps. Les distances journalières prédites étaient plus longues pendant la saison de fructification (6, 98 km) que pendant la saison de non-fructification (6, 06 km). Ces différences saisonnières suggèrent des réponses aux changements de ressources alimentaires et de température. Les taux de détection des pièges photographiques ont montré des tendances temporelles et saisonnières similaires à celles des données de suivi, ce qui nous permet de généraliser nos conclusions au niveau de la population. De plus, les caméras n’ont jamais détecté les mandrills la nuit, et nous avons observé qu’ils dormaient haut dans les arbres et ne bougeaient pratiquement pas jusqu’au lendemain matin, ce qui suggère qu’ils évitent strictement de se déplacer la nuit. Cette étude a démontré l’importance de l’approche à méthodes multiples pour tirer des conclusions solides sur les modes temporels de déplacement des animaux

Female Reproductive Seasonality and Male Influxes in Wild Mandrills (Mandrillus sphinx)

The correlates of variation in the number of males in primate groups form a long-standing question in primatology. We investigated female reproductive seasonality and the numbers of males in groups of wild mandrills (Mandrillus sphinx) in a 25-month camera-trap survey with 160 camera locations in Moukalaba-Doudou National Park, Gabon. We used 1760 videos to analyze group composition, including the presence of females with newborn infants and with sexual swellings, the number of males present in groups, and male spatial positioning in groups. Female reproduction was seasonal, with a peak in the number of newborns in the mid-rainy season and a peak in the number of females with sexual swellings in the early dry season. The number of males in the group increased in the dry season, with a much greater increase in the number of mature males (sevenfold) than in submature males (twofold). The peak number of mature males, but not submature males, in the group lagged significantly behind the peak in the number of females with sexual swellings, suggesting that submature males enter groups before mature males and/or that mature males stay in the group longer after the peak of females with sexual swellings. Mature, but not submature, males appeared frequently near females with sexual swellings. In conclusion, we found a clear relationship between the presence of receptive females and the number of males in the group, and evidence that male competitive ability influences male strategies

Predicting bushmeat biomass from species composition captured by camera traps: Implications for locally based wildlife monitoring

アフリカ熱帯雨林における野生動物資源量推定の有効な指標を発見 --地域住民主体の野生動物モニタリング法の基礎を確立--. 京都大学プレスリリース. 2022-08-26.Cameras candidly capture bushmeat mammals to avert crisis. 京都大学プレスリリース. 2022-08-30.1. Facing the bushmeat crisis, tropical forests require effective monitoring for sustainable wildlife management. To gain credibility with local people and conservation officials, the monitoring needs indicators that comply with local knowledge and predict the available faunal resources. 2. This study explores predictive indicators for bushmeat biomass --the total biomass of five main hunted mammals-- in a Cameroonian rainforest. We employed camera trapping and the Random Encounter and Staying Time (REST) model to estimate the spatial variation in each species' population density and bushmeat biomass at three sites. We then calculated six indicators from camera-trap capture rate estimates and assessed their predictive performance for the total wild meat amount. 3. Duikers generally increased with distance from the public road, but two red duiker species were more markedly affected by the distance than blue duikers. Spatial density patterns of brush-tailed porcupines and Emin's pouched rats differed between sites. Consequently, bushmeat biomass displayed exponential growth away from the road with varying degrees among the sites. 4. Of the six indicators, the R/B ratio (red-to-blue duiker ratio) and the D/R ratio (duiker-to-rodent ratio) exhibited positive linear-like correlations to bushmeat biomass at all sites. The correlation lines were moderately similar across sites in the R/B ratio but largely different in the D/R ratio, suggesting that the latter is unsuitable for sharing information between neighbouring communities. 5. Synthesis and applications. The two indicators based on captured animal composition may effectively predict the total biomass of the main target species for bushmeat hunting, given a reasonably large sample size. The R/B ratio (red duikers/blue duikers) is recommended as a first choice; the D/R ratio (duikers/rodents) can be a good alternative when information sharing is not essential. Because local hunters are aware of depletion-related changes in species composition of caught animals, these indices may be effectively incorporated into community-based wildlife monitoring.1. Face à la crise de la viande de brousse, les forêts tropicales nécessitent un système de suivi efficace pour une gestion durable de la faune. Pour gagner en crédibilité auprès des populations locales et des responsables de la conservation, le suivi a besoin d'indicateurs qui respectent les connaissances locales et prédisent les ressources fauniques disponibles. 2. Cette étude explore des indicateurs prédictifs de la biomasse de la viande de brousse --la biomasse totale de cinq principaux mammifères chassés-- dans une forêt tropicale camerounaise. Nous avons utilisé des caméra-piège et le modèle REST (Random Encounter and Staying Time) pour estimer la variation spatiale de la densité de chaque espèce et de la biomasse de viande de brousse sur trois sites. Nous avons ensuite calculé six indicateurs à partir des estimations du taux de capture par caméra-piège et évalué leur performance prédictive pour la quantité totale de viande sauvage. 3. Le nombre de céphalophes augmentaient généralement avec la distance de la route publique, mais deux espèces de céphalophes roux étaient plus fortement affectés par la distance que les céphalophes bleus. Les modèles de densité spatiale des porcs-épics et des rats géants d'Emin différaient selon les sites. Par conséquent, la biomasse de viande de brousse a affiché une croissance exponentielle en s'éloignant de la route, avec des degrés variables selon les sites. 4. Parmi les six indicateurs, le ratio R/B (le ratio des céphalophes rouges par rapport aux céphalophes bleus) et le ratio D/R (le ratio des céphalophes par rapport aux rongeurs) présentaient des corrélations linéaires avec la biomasse de viande de brousse sur tous les sites. Les lignes de corrélation étaient modérément similaires d'un site à l'autre pour le ratio R/B mais largement différentes pour le ratio D/R, ce qui suggère que ce dernier n'est pas approprié pour le partage d'informations entre communautés adjacentes. 5. Synthèse et applications. Les deux indicateurs basés sur la composition des animaux capturés peuvent prédire efficacement la biomasse totale des principales espèces cibles de la chasse à la viande de brousse, à condition de disposer d'une taille d'échantillon raisonnablement importante. Le ratio R/B (les céphalophes rouges/bleus) est recommandé comme premier choix; le ratio D/R (les céphalophes/les rongeurs) peut être une bonne alternative lorsque le partage des informations n'est pas essentiel. Comme les chasseurs locaux sont conscients des changements liés à l'épuisement dans la composition des espèces des animaux capturés, ces indicateurs peuvent être efficacement intégrés dans le suivi communautaire de la faune

Morphological character changes through decapodid-stage larva and juveniles in the ghost shrimp Nihonotrypaea harmandi from western Kyushu, Japan: Clues for inferring pre- and post-settlement states and processes

Some decapod crustaceans release larvae from estuarine or coastal shores to coastal oceans. Decapodids (last-stage larvae) return home, settle, and metamorphose into juveniles I, which go through further instars. Several morphological characters degenerate or develop in response to lifestyle transitions. Using a burrow-dwelling callianassid shrimp, Nihonotrypaea harmandi, inhabiting an intertidal sandflat in a coastal boundary layer adjacent to coastal ocean, this study described morphological changes and drew inferences about states and processes in its early life history. Decapodid and juveniles were differentiated by linea thalassinica on carapace. In the laboratory, the decapodid stage lasted 3-6d. Given choice between sandy sediments from coastal ocean bed and adult habitat, decapodids exhibited no preference, suggesting broad receptiveness. The shortest durations of the juvenile-I, -II, and -III were estimated at 6d each. Starved decapodids normally metamorphosed into juveniles I, showing secondary lecithotrophy. The non-feeding state could be extended through the juvenile I (and possibly juvenile II), where the mean total lengths of shrimps reared in groups with food (diatoms) remained about 4.6mm. Post-settlement decapodids reared individually resumed feeding. The rostrum lengths in decapodids were ≥0.36mm on the initial two dates (Days 0 and 1), after which the mean values rapidly reduced to 0.30-0.36mm on Day 2 and below 0.30mm thereafter. The pereiopod exopods disappeared through the decapodid stage from four pairs to almost zero by Day 4. In the coastal ocean, no juveniles occurred, and almost all decapodids had rostrum lengths ≥0.30mm and 3 or 4 pereiopod exopods, suggesting their pre-settlement state. Of the smallest shrimps collected on the sandflat for their subsequent rearing there, 74% were estimated to be Day-0 or -1 decapodids based on their rostrum lengths. This and the laboratory experimental results suggest (1) the acquisition of competence for settlement by newly-metamorphosed decapodids while in the coastal ocean, which was nevertheless realized there and (2) their rapid transport by flood tidal currents from coastal ocean to sandflat. The newly-settled decapodids grew steadily at 0.2mmd-1 in total length. The reared juveniles reached the smallest adult size in 80d. The uropod expod changed from elliptical to sub-circular in shape markedly around the termination of the juvenile II or III, suggesting the acquisition of ventilating function for benthic life. Overall, the post-settlement shrimps can be staged by total-length ranges as 4-5.5mm for decapodids, 5.5-10mm for juveniles, and 10-20mm for sub-adults. •Decapodid and juveniles of a callianassid shrimp were reared in laboratory and field.•Ontogenetic morphological change and growth in decapodid and juveniles were given.•Feeding mode, substratum selectivity, and duration for decapodid stage were examined•Two degenerating characters gave clues to infer states in field-collected decapodids.•One developing character in juveniles was related with burrow-dwelling lifestyle

Etude de la Relation entre l’abondance des grands mammifères frugivores et celle des fruits dans le Parc National de Moukalaba-Doudou, Gabon

Au Gabon, les travaux portant sur les relations plantes animaux demeurent encore très lacunaires. Pourtant, cette connaissance est indispensable dans la compréhension des fonctionnements des écosystèmes forestiers, mais aussi sur le comportement alimentaire des mammifères. C’est dans ce cadre qu’une étude sur l’abondance des mammifères frugivores et celles des fruits a été conduite dans le Parc National de Moukalaba Doudou. Les données sur l’abondance des mammifères ont été recueillies à l’aide des caméras pièges, le long de 11 transects de janvier 2012 à janvier 2014. Quant aux fruits, ils ont été récoltés le long de ces transects sur une bande de 1 m de large de part et d’autre du transect. Au total, 2492 fruits repartis en 100 espèces ont été recensés au cours de cette étude. Le nombre de fruits recensés a varié en fonction des biotopes prospectés et des mois. Les caméras pièges ont permis d’identifier dix espèces de mammifères frugivores présents dans cette zone. Le test de corrélation P de Pearson (R= 0,2 ; df= 10, P= 0,5) a montré que la variation entre l’abondance des mammifères et celle des fruits reste indépendante.Mots clés : Abondance, fruits, mammifères, Parc National Moukalaba-Doudou, caméra piège, Gabon

Host selection of hematophagous leeches (Haemadipsa japonica): Implications for iDNA studies

The development of an efficient and cost‐effective method for monitoring animal populations or biodiversity is urgently needed, and invertebrate‐derived DNA (iDNA) may offer a promising tool for assessing the diversity and other ecological information of vertebrates. We studied the host species of a hematophagous leech (Haemadipsa japonica) in Yakushima by genetic barcoding and compared the results with those for mammal composition revealed by camera trapping. We analyzed 119 samples using two sets of primers by Sanger sequencing and one set of primer by next generation sequencing. The proportion of the samples that were successfully sequenced and identified to at least one species was 11.8–24.3%, depending on the three different methods. In all of these three methods, most of the samples were identified as sika deer (18/20, 6/15 and 16/29) or human (2/20, 7/15 and 21/29). The nonhuman mammal host species composition was significantly different from that estimated by camera trapping. Sika deer was the main host, which may be related with their high abundance, large body size and terrestriality. Ten samples included DNA derived from multiple species of vertebrates. This may be due to the contamination of human DNA, but we also found DNA from deer, Japanese macaque and a frog in the same samples, suggesting the mixture of the two meals in the gut of the leech. Using H. japonica‐derived iDNA would not be suitable to make an inventory of species, but it may be useful to collect genetic information on the targeted species, due to their high host selectivity

Stable isotopic investigation of the feeding ecology of wild Bornean orangutans

Objectives We applied stable carbon and nitrogen isotope analyses to wild Bornean orangutans (Pongo pygmaeus morio) to investigate the feeding ecology of wild orangutans. Compared with African great ape species, orangutans are adapted to environments with chronic lower nutrition. But the usefulness of stable isotope analysis in the study of wild orangutan feeding ecology has not been fully explored. Methods The study site was a primary lowland dipterocarp forest in the Danum Valley, Sabah, Malaysia. A total of 164 plant and 94 fecal samples collected across 18 months were analyzed. Results Carbon and nitrogen stable isotope ratios of plant food samples do not systematically vary by plant parts (i.e., bark, fruits, and leaves). Elemental composition and stable isotope ratios of orangutan feces do not systematically vary by orangutans' sex and age classes, although fecal stable isotope ratios showed seasonal fluctuations. No isotopic contribution of breast milk was found in fecal samples collected from individuals at 2.7–6.5 years of age. Conclusions This study revealed key characteristics of the stable isotope ecology of wild orangutans living in a primary lowland forest. Although there was little isotopic variation among plant foods and orangutan individuals, seasonal fluctuations in baseline isotope ratios or orangutans' diet were found in Danum valley

New evidence from observations of progressions of mandrills (Mandrillus sphinx): a multilevel or non-nested society?

African papionins are well known for the diversity of their social systems, ranging from multilevel societies based on one-male-multifemale units (OMUs) to non-nested societies. However, the characteristics of Mandrillus societies are still unclear due to difficult observational conditions in the dense forests of central Africa. To elucidate the characteristics of mandrill societies and their social systems, I analysed the age-sex compositions, behaviours, and progression patterns of their horde/subgroups using videos of them crossing open places. The progressions were very cohesive, and the very large aggregations (169-442 individuals) had only 3-6 adult males (1.4-1.8 % of all individuals) and 11-32 subadult males (6.5-7.2 %). No herding behaviours were observed in the males, and most of the small clusters within the progressions were not analogous to the OMUs of a multilevel society but instead consisted of only adult females and immatures. The progressions of alert mandrills showed patterns similar to those observed in a non-nested social system: females with dependent infants were concentrated toward the rear and adult and subadult males toward the front. These results suggest that cohesive aggregations and a female-biased sex ratio are common characteristics of mandrill species. Mandrills may form female-bonded and non-nested societies, although their fission-fusion dynamics may be different from those typical of savannah baboons

Females Move in Tight Crowds, Males Roam: Socioecology and Movement Ecology of Mandrills

Mandrills (Mandrillus sphinx) have a unique social system for primates, with huge groups of hundreds of individuals and males moving in and out of the group seasonally. Despite intensive field studies conducted at several sites in the Congo Basin rainforests, the mechanisms and adaptation of their social organization are still poorly understood. How do groups maintain their huge size while moving around in the forest with poor visibility? How do solitary males find groups in the vast forests? And what are the adaptive advantages of these behaviors? In this review, I summarize what we know surrounding these questions and compare mandrill ecology with that of Neotropical social mammals, offering potential explanations for these questions. Group crowdedness and frequent exchange of long-distance calls could be keys to the collective movement of large groups that engage in regular subgrouping. The adaptive benefits of the large group size possibly lie in female tactics relating to infanticide avoidance and polyandrous mating. While very little is known about how solitary males find groups at the onset of the mating season, the adaptive function of their seasonal influxes can be relatively well explained as foraging and mating tactics. Since the major questions of mandrill social organization are strongly related to their movement ecology, intensive movement research using GPS telemetries and remote sensing is crucially needed to disentangle the social system of this intriguing monkey. Further, broader comparisons among the social movement of rainforest mammals will be essential to comprehensively understand their movement ecology