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Wild chimpanzees on the edge: nocturnal activities in croplands.

Krief S, Cibot M, Bortolamiol S, Seguya A, Krief JM, Masi S - PLoS ONE (2014)

Bottom Line: They also stayed longer in the maize field and presented few signs of vigilance and anxiety during these nocturnal crop-raids.While nocturnal activities of chimpanzees have been reported during full moon periods, this is the first record of frequent and repeated nocturnal activities after twilight, in darkness.Habitat destruction may have promoted behavioural adjustments such as nocturnal exploitation of open croplands.

View Article: PubMed Central - PubMed

Affiliation: UMR 7206 CNRS/MNHN/P7, Eco-anthropologie et d'ethnobiologie, Hommes, Natures, Sociétés, Museum national d'histoire naturelle, Paris, France; Projet pour la conservation des grands singes, Kibale National Park, Fort Portal, Uganda.

ABSTRACT
In a rapidly changing landscape highly impacted by anthropogenic activities, the great apes are facing new challenges to coexist with humans. For chimpanzee communities inhabiting encroached territories, not bordered by rival conspecifics but by human agricultural fields, such boundaries are risky areas. To investigate the hypothesis that they use specific strategies for incursions out of the forest into maize fields to prevent the risk of detection by humans guarding their field, we carried out video recordings of chimpanzees at the edge of the forest bordered by a maize plantation in Kibale National Park, Uganda. Contrary to our expectations, large parties are engaged in crop-raids, including vulnerable individuals such as females with clinging infants. More surprisingly chimpanzees were crop-raiding during the night. They also stayed longer in the maize field and presented few signs of vigilance and anxiety during these nocturnal crop-raids. While nocturnal activities of chimpanzees have been reported during full moon periods, this is the first record of frequent and repeated nocturnal activities after twilight, in darkness. Habitat destruction may have promoted behavioural adjustments such as nocturnal exploitation of open croplands.

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Party composition during forest feeding activities and activities at the border of the maize field.
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pone-0109925-g003: Party composition during forest feeding activities and activities at the border of the maize field.

Mentions: The 120 clips of chimpanzee records provided 354 individual sessions. Those individual sessions in which sex and age class of individuals can be identified (330 out of 354) showed the presence of all age/sex classes (n of sessions for adult males: 56, adult females: 144, sub-adult females: 12, sub-adult males: 12, juveniles: 61, infants: 45) with a proportion not significantly different from the usual party composition of Sebitoli community during feeding bouts (Figure 3, Chi-Square = 0,232, df = 5, P = 0.999). In the 277 individual follows in which we were able to determine the exact identity of the individual (Nindividual = 29; mean number of clips/individual = 9.60; range: 1–39), mean time in the videos/individual = 4′05″ (8′–25′28″), 139 observations correspond to females (55′47″), 138 to males (1h00’21″) and 134 correspond to chimpanzees going into the field, 119 coming back from the field, 24 being along the trench. Vulnerable individuals such as females with clinging infants (N = 3, respectively in 39, 5 and 2 clips) and severely mutilated individuals were recorded on clips, these include two individuals missing feet (1′24″ on 6 clips and 59″ in 3), a female missing four fingers to the left hand (3′03″ in 10 clips) and a juvenile with an unconsolidated broken leg (13′17″ in 33 clips). Mainly females led the party entering the maize field (five out of seven crop-raiding events).


Wild chimpanzees on the edge: nocturnal activities in croplands.

Krief S, Cibot M, Bortolamiol S, Seguya A, Krief JM, Masi S - PLoS ONE (2014)

Party composition during forest feeding activities and activities at the border of the maize field.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4206271&req=5

pone-0109925-g003: Party composition during forest feeding activities and activities at the border of the maize field.
Mentions: The 120 clips of chimpanzee records provided 354 individual sessions. Those individual sessions in which sex and age class of individuals can be identified (330 out of 354) showed the presence of all age/sex classes (n of sessions for adult males: 56, adult females: 144, sub-adult females: 12, sub-adult males: 12, juveniles: 61, infants: 45) with a proportion not significantly different from the usual party composition of Sebitoli community during feeding bouts (Figure 3, Chi-Square = 0,232, df = 5, P = 0.999). In the 277 individual follows in which we were able to determine the exact identity of the individual (Nindividual = 29; mean number of clips/individual = 9.60; range: 1–39), mean time in the videos/individual = 4′05″ (8′–25′28″), 139 observations correspond to females (55′47″), 138 to males (1h00’21″) and 134 correspond to chimpanzees going into the field, 119 coming back from the field, 24 being along the trench. Vulnerable individuals such as females with clinging infants (N = 3, respectively in 39, 5 and 2 clips) and severely mutilated individuals were recorded on clips, these include two individuals missing feet (1′24″ on 6 clips and 59″ in 3), a female missing four fingers to the left hand (3′03″ in 10 clips) and a juvenile with an unconsolidated broken leg (13′17″ in 33 clips). Mainly females led the party entering the maize field (five out of seven crop-raiding events).

Bottom Line: They also stayed longer in the maize field and presented few signs of vigilance and anxiety during these nocturnal crop-raids.While nocturnal activities of chimpanzees have been reported during full moon periods, this is the first record of frequent and repeated nocturnal activities after twilight, in darkness.Habitat destruction may have promoted behavioural adjustments such as nocturnal exploitation of open croplands.

View Article: PubMed Central - PubMed

Affiliation: UMR 7206 CNRS/MNHN/P7, Eco-anthropologie et d'ethnobiologie, Hommes, Natures, Sociétés, Museum national d'histoire naturelle, Paris, France; Projet pour la conservation des grands singes, Kibale National Park, Fort Portal, Uganda.

ABSTRACT
In a rapidly changing landscape highly impacted by anthropogenic activities, the great apes are facing new challenges to coexist with humans. For chimpanzee communities inhabiting encroached territories, not bordered by rival conspecifics but by human agricultural fields, such boundaries are risky areas. To investigate the hypothesis that they use specific strategies for incursions out of the forest into maize fields to prevent the risk of detection by humans guarding their field, we carried out video recordings of chimpanzees at the edge of the forest bordered by a maize plantation in Kibale National Park, Uganda. Contrary to our expectations, large parties are engaged in crop-raids, including vulnerable individuals such as females with clinging infants. More surprisingly chimpanzees were crop-raiding during the night. They also stayed longer in the maize field and presented few signs of vigilance and anxiety during these nocturnal crop-raids. While nocturnal activities of chimpanzees have been reported during full moon periods, this is the first record of frequent and repeated nocturnal activities after twilight, in darkness. Habitat destruction may have promoted behavioural adjustments such as nocturnal exploitation of open croplands.

Show MeSH
Related in: MedlinePlus