Tuesday, May 15, 2012

Changes Continue in Pablo Group

Isura with  her new friends in the Karisimbi group.                              Two gorillas have left Pablo’s group, bringing the number of the largest group of mountain gorillas down to 44 individuals. Isura, a subadult 7-year-old female and offspring of Mukecuru (the older female who gave birth to her sixth infant last week) transferred to Karisimbi’s group, which is one of the groups monitored by the Rwandan Development Board (RDB) and used for tourism. Additionally, 12-year-old Mafunzo dispersed to become a lone silverback, in the hopes of acquiring females and assembling his own group in the future.
On Wednesday May 9, Karisoke Research Center trackers were unable to locate Isura in Pablo's group and Mafunzo had gone missing two days prior. Initially, the female was not thought to have transferred. The group was ranging in dense bamboo in the Gashinga area, on the bottom of the slopes of Mount Karisimbi. Due to the dense vegetation and heavy rains, the field staff suspected that she could be hidden somewhere close by.

The Karisoke trackers assigned to Pablo's group made an intense search the following day when, again, neither gorilla was located and the field staff began to believe that the two gorillas had left together. After several days of searching, on Sunday, May 13 the team found a trail (of one of the two gorillas) coming from Pablo’s group. The trail led in the direction of the Karisimbi group, directly to the nest of a silverback.  The Karisoke trackers called the RDB staff in charge of monitoring the Karisimbi group to inquire if they had observed any unfamiliar gorillas near their group. The RDB trackers had in fact seen an unknown female arrive in the group a few days prior.

With this news, Karisoke's Pablo trackers trekked to the Karisimbi group and successfully identified the unknown female as Isura. They reported that she is fine and perfectly integrated into her new group. She was often observed close to Ruhuka, a female that transferred from Pablo's to Susa’s group in 2009, grooming and resting in close physical contact. The two females are familiar with each other from the years they spent together in Pablo's group.

Even Getty, the group’s dominant silverback, was seen resting close to Isura, meticulously grooming her. Although he displayed once towards her, he quickly calmed down and began to warm to the new female. “Even if the dynamic of the transfer is still not clear, the staff of the Karisoke Research Center was happy to see Isura healthy and well established in the Karisimbi group” says Karisoke Gorilla Program Manager Veronica Vecellio.  “A missing gorilla, especially if it is a female, always raises concerns and requires a massive effort for a search to be carried out on top of the routine daily tracking of all gorilla groups.”

As for the dispersed silverback Mafunzo, the field staff was unable to locate him. He is a silverback and, even if he is on the young side, he is still within the normal age range to strike out on his own. In fact, Mafunzo had left and rejoined the group twice before this last disappearance. It is likely that the nest found close to the Karisimbi group was in fact his nest, if he was on the trail of Isura before she made the final transfer. Mafunzo’s decision to become a lone silverback is not surprising, as he is the brother of Pablo's group’s dominant silverback, Cantsbee, and related to most of the Pablo group's gorillas, including sexually active females.

As of this afternoon, the field staff reported that Pablo's group has split into two subgroups once again, with Cantsbee leading 16 individuals and Gicurasi leading 26. The entire group nested together last night in the same location where Cantsbee's subgroup is ranging at the present time. Because the bamboo is a limited resource, it is very likely that Gicurasi led another group to an area with more food availability, to avoid overcrowding.

Jessica Burbridge, Field Communications Officer

All Images © The Dian Fossey Gorilla Fund International

To read more of the Fossey Fund blog, please click here.

Friday, May 11, 2012

Pablo Female Gives Birth, Largest Group of Gorillas Rises to 46

Pablo's group became 46 individuals today when the Fossey Fund’s Karisoke Research Center trackers arrived at the group and noticed that Mukecuru, an older female estimated to be between 26 and 32 years of age, had given birth. The Karisoke field staff have suspected for several months now that Mukecuru was expecting. Her belly has been exceptionally rotund and she has been observed moving slowly, appearing lethargic and uncomfortable. At her age, this will be one of her last offspring to be born. As she lost her two previous infants in 2007 and 2009, the field staff is hoping this new baby will survive.

Mukecuru transferred from the Susa group to Pablo's group in 1995, and at the time she was estimated to be 16 years old. She gave birth in 1996, just one year after her transfer. Although it can not be said for sure, it was likely that Mukecuru was nulliparous (had not given birth yet) when she transferred into Pablo's group, in which case this would have been her first infant and she could actually have been as young as 10 years old. If Mukecuru is in fact closer to 32 years old now, this may be the last infant she will bear. Based on the long-term research at Karisoke, female gorillas tend to live longer than males and can remain reproductively active until their death, unlike humans. Mukecuru’s new infant is her sixth. The baby joins siblings Mitimbili (a 16-year-old adult female) and Isura (a 7-year-old subadult female) in Pablo's group. The infant’s third surviving sibling, 12-year-old Umwe, transferred to the Susa group in 2007.

According to Karisoke’s copulation records, Mukecuru was copulating primarily with Gicurasi, the beta-male of Pablo's group, nine months ago. The field staff reports that Mukecuru spends much of her time with this silverback. “It will be interesting to see how both Gicurasi and [dominant silverback] Cantsbee react to the infant” says Gorilla Program Manager Veronica Vecellio. It will be at least six months before the Karisoke researchers are able to collect viable DNA samples to determine paternity for this youngster, though. At least five fecal samples will be collected and shipped to the Max Planck Institute in Germany when the time comes.

It is possible that Mukecuru gave birth yesterday, because the team was not able to reach Pablo's group that day due to rain, flood waters and rising rivers. The Karisoke trackers reported that the baby appeared healthy this morning, but because of the inclement weather at this time of year it’s a difficult time for a youngster to be born.

Anti-poaching News

In the second mixed patrol of 2012 conducted by the Congolese park authority (ICCN) and Karisoke trackers, 105 snares were found in the last six days. This patrol covered the trans-border area on the northern side of Mount Visoke, called Kaniampereri. It has been some time since this area was combed for snares and other illegal activities, but this alarmingly high number is cause for concern for the gorillas that range along the border between the Democratic Republic of Congo and Rwanda.

Jessica Burbridge, Field Communications Officer

All images © Dian Fossey Gorilla Fund International

To read more of the Fossey Fund's blog, please click here.

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