Publications of Eva Gazagne
Bookmark and Share    
Full Text
See detailSeed shadows of northern pigtailed macaques within a degraded forest fragment, Thailand
Gazagne, Eva ULiege; Pitance, Jean-Luc ULiege; Savini, Tommaso ULiege et al

in Revue de Primatologie (2020, December 10), 11

Determining seed shadow (i.e. seed deposition pattern of a plant population) produced by frugivores is difficult to evaluate by direct observations, although of paramount importance to understand their ... [more ▼]

Determining seed shadow (i.e. seed deposition pattern of a plant population) produced by frugivores is difficult to evaluate by direct observations, although of paramount importance to understand their effectiveness as seed dispersal agents in degraded habitat. We developed a modeling approach of seed shadows incorporating field-collected data on a troop of 141 ± 10 individuals of northern pigtailed macaques (Macaca leonina) inhabiting a degraded forest fragment in Thailand, by implementing a mechanistic model of seed deposition with random components. We parameterized the model with macaque feeding behavior (i.e. consumed fruit species, seed treatments), gut and cheek pouch retention time, location of feeding sites and sleeping sites, monthly photoperiod, and movement patterns based on monthly native fruit availability using Hidden Markov models (HMM). We found that northern pigtailed macaques dispersed a majority of medium- to large-seeded species across large distances (mean > 500 m, maximum distance of 2300 m), promoting genetic mixing and colonization of plantation forests. Additionally, the macaques produced complementary seed shadows, with a sparse distribution of seeds spat out locally (mean > 50 m, maximum distance of 870 m) that probably ensures seedling recruitment of the immediate plant populations. Macaques’ large dispersal distance reliability is often underestimated and overlooked; however, their behavioral flexibility places them among the last remaining dispersers of large seeds in disturbed habitats. Our study shows that this taxon is likely to maintain significant seed dispersal services and promote forest regeneration in degraded forest fragments. [less ▲]

Detailed reference viewed: 30 (5 ULiège)
Full Text
See detailSeed Shadows of Northern Pigtailed Macaques within a Degraded Forest Fragment, Thailand
Gazagne, Eva ULiege; Pitance, Jean-Luc ULiege; Savini, Tommaso ULiege et al

in Forests (2020), 11(1184), 1-24

Abstract: Research Highlights: Frugivores able to disperse large seeds over large distances are indispensable for seedling recruitment, colonization and regeneration of tropical forests. Understanding ... [more ▼]

Abstract: Research Highlights: Frugivores able to disperse large seeds over large distances are indispensable for seedling recruitment, colonization and regeneration of tropical forests. Understanding their effectiveness as seed dispersal agents in degraded habitat is becoming a pressing issue because of escalating anthropogenic disturbance. Although of paramount importance in the matter, animal behaviour’s influence on seed shadows (i.e., seed deposition pattern of a plant population) is difficult to evaluate by direct observations. Background and Objectives: We illustrated a modeling approach of seed shadows incorporating field-collected data on a troop of northern pigtailed macaques (Macaca leonina) inhabiting a degraded forest fragment in Thailand, by implementing a mechanistic model of seed deposition with random components. Materials and Methods: We parameterized the mechanistic model of seed deposition with macaque feeding behavior (i.e., consumed fruit species, seed treatments), gut and cheek pouch retention time, location of feeding and sleeping sites, monthly photoperiod and movement patterns based on monthly native fruit availability using Hidden Markov models (HMM). Results: We found that northern pigtailed macaques dispersed at least 5.5% of the seeds into plantation forests, with a majority of medium- to large-seeded species across large distances (mean > 500 m, maximum range of 2300 m), promoting genetic mixing and colonization of plantation forests. Additionally, the macaques produced complementary seed shadows, with a sparse distribution of seeds spat out locally (mean >50 m, maximum range of 870 m) that probably ensures seedling recruitment of the immediate plant populations. Conclusions: Macaques’ large dispersal distance reliability is often underestimated and overlooked; however, their behavioral flexibility places them among the last remaining dispersers of large seeds in disturbed habitats. Our study shows that this taxon is likely to maintain significant seed dispersal services and promote forest regeneration in degraded forest fragments. [less ▲]

Detailed reference viewed: 38 (7 ULiège)
Full Text
See detailToward a better understanding of habituation process to human observer: A statistical approach in Macaca leonina (Primates: Cercopithecidea)
Gazagne, Eva ULiege; Hambuckers, Alain ULiege; Savini, Tommaso ULiege et al

in Raffles Bulletin of Zoology (2020), 68(2020), 735-749

Habituation allows an observer to closely approach and follow free-ranging animals, as they no longer respond to the observer presence (e.g., through flight, avoidance, display, curiosity). While ... [more ▼]

Habituation allows an observer to closely approach and follow free-ranging animals, as they no longer respond to the observer presence (e.g., through flight, avoidance, display, curiosity). While habituation is implicitly acknowledged as a necessary step before any direct observational studies of primates, there is very little published data on the subject. The aim of this study is to analyse the habituation process over time (17 months) in a wildfeeding troop of northern pigtailed macaques (Macaca leonina) inhabiting a degraded forest fragment of the Sakaerat Biosphere Reserve, Thailand. Based on the number of encounters, contact duration with the studied troop, and behavioural responses to the observer recorded ad libitum and via scan sampling, we found statistical evidence of habituation progress over five stages: early, minimal, partial, advanced, and full. The complete habituation process took nearly 13 months. Factors such as the macaques’ limited experience of human contact, semi-terrestriality, large ranging patterns, fission-fusion dynamics, unpredictable resource use, as well as reduced native fruit availability in this degraded forest fragment may explain the length of the process. It was only possible to collect ranging and behavioural data from the partial habituation stage, although these data were biased toward adult males and sub-adults, while overestimating movement behaviour over inactivity and social behaviours. Our results highlight the importance of analysing behavioural data of fully habituated groups of primates to limit biases of observer presence, and also of not underestimating the habituation process length. This study provides novel information on the habituation process in macaques and proposes an effective methodology to analyse the habituation process across a wide range of primate species. [less ▲]

Detailed reference viewed: 143 (9 ULiège)