Eight Months in the Forest Canopy

To be exact: Eight months spent watching a single forked branch, 17 meters (56 feet) above the ground in the Congo’s Lomami National Park.

Base of an Uapaca
The aerial roots is usually all we see of an Uapaca tree. The slash confirmed its identification.

My name is Daniel Alempijevic, a graduate student from Kate Detwiler’s Primatology lab at Florida Atlantic University. I lead a collaborative camera trap study with the TL2 Project.

A forked Uapaca branch was faithfully observed by “Euvgenia Cam” for 8 mohths. The camera is named after its donor.

In the Lomami River Basin, a diverse group of primates scour the canopy in search of fruits, insects, and palatable leaves. Each species has unique feeding strategies and tolerances that allow co-existence with other species. Sometimes they form mixed-species groups. Observing the natural behavior of monkeys from the ground in dense, closed canopy forests is daunting, so we use arboreal camera traps.

As part of a camera trap survey designed to detect Inoko (Cercopithecus dryas) in TL2, one camera recorded animal encounters throughout the fruiting period of a Uapaca heudelotii tree.

Some of the Uapaca fruit within the camera trap’s detection zone.

Since the camera was setup (Dec 3,2016) through mid-April, primates were making consistent but infrequent visits to the tree, averaging less than two primate detections per week (n=1.75). Then, over an 8-week period between April and June the frequency of detections per week greatly increased (n=9), with 14 primate detections during one week in May.

The reason for this spike in detections is clear; this was when the Uapaca fruits were ripe and all monkeys converged on it. The number of videos showing primates collecting and eating fruit show the same trend as the primate detection frequency. After this period of increased foraging, the primate detections decrease (n=2.4) through the remaining 5 weeks. During the 8-month period, 6 of the 8 diurnal primate species known to occur in this part of the forest were recorded; the elusive and sub-canopy dwelling Inoko, along with the bonobo, however, never came to that forked branch.

The 6 species of primates detected by the camera trap. The colobus is the only one that is mainly a leaf eater. Here the independent clips have been spliced together. Note the hornbill at the end of the video; they too are important seed dispersers.

This video from the Uapaca branch revealed an important aspect of tropical ecology, the relationship between tree and frugivore. Tropical forests are rich in fruits of various sizes, colors, and palatability. This variation in fruit is matched by a diverse frugivorous community of birds and mammals. Carbohydrate-rich fruits contain seeds that can survive digestion unscathed and sprout in a new location after passing through the animal. This is a primary means of dispersal for tropical tree species. Fruits are a patchy resource, both in space and in time. Fruit density is highest during the dry season, having matured during the rains.

Primate density at a site is dependent largely on availability of food. Monkeys disperse over large areas when fruits are not readily available, converging where fruit density is highest. The distribution and density of fruiting trees starts with their dispersal. The patterns of animal movement, responsible for much of the dispersal, can thereby trace an early blueprint of forest composition.


  1. Reiko
    Posted 2017-09-19 at 11:22 pm | Permalink

    Hi, Terese. TL2 is an amazing place. At 42 seconds into the video above, there is a guenon that looks like a hybrid, but there was no label. Is it a hybrid between blue and red-tail?

  2. Posted 2017-09-20 at 4:53 pm | Permalink

    Loved this post,
    Shared here 9/20/17: facebook.com/biointegrity
    Sending our gratitude to everybody on your team — Thanks, Terese!

  3. Terese Hart
    Posted 2017-09-20 at 6:02 pm | Permalink

    Kate Detwiler, Daniel’s major professor is particularly interested in hybrid areas and that is what attracks her to TL2. I flagged your comment to her.

  4. michael
    Posted 2017-10-03 at 4:41 pm | Permalink

    In the video we saw an African Giant Squirrel.
    Now compare with the Distribution Map in IUCN Redlist

  5. Terese Hart
    Posted 2017-10-03 at 5:17 pm | Permalink

    Interesting observation, Michael. I’ve pointed it out to John Hart. Daniel is now in the forest, but will soon be back to Kindu and we will ask about other Giant Squirrel video clips from the Camera Traps.

  6. John Hart
    Posted 2017-10-04 at 9:52 pm | Permalink

    Michael, thank you for your observation on the distribution of the Giant Squirrel. The IUCN Red List distribution is taken from the species profile in Mammals of Africa (2013), which provides no discussion of the proposed hiatus in the range of the species between the Lomami and the Lualaba. Yet we have seen this species on numerous occasions in this forest, confirmed by the camera trap videos. Kingdon, in the second edition of his field guide (2015), does not show this hiatus in the range map. Perhaps the 2013 mapped hiatus was due to lack of information at the time the map was compiled. The possibility of an erroneous map in MoA is not to be excluded. The subspecies, signatus is reported to range from the Congo River west to the Kasai River, in DRC. This would include the supposed range hiatus. The Giant Squirrel has a large distribution, many proposed subspecies and is often common.

  7. michael
    Posted 2017-10-05 at 8:04 am | Permalink

    Thanks John,

    another hiatus we can see in kingdon ( 2015 ) is that of the blue monkey ( in the video ). According to kingdon it is limited to the forests east of the lomami, you confirmed it for the forests west of the lomami ( ngoyi ) and in a paper of 1983
    (Hunting of the Boyela, Slash-and-Burn Agriculturalists, in the Central Zaire Forest ) it is listed as part of the hunters game even west of the tshuapa. This puzzling ranges of the mammals south of the congo river is really a faszinating miracle.

  8. John Hart
    Posted 2017-10-07 at 11:27 am | Permalink

    Hi Michael
    Thank you for these further comments. You are correct, the distribution of blue monkeys (and other species) in Congo’s Central cuvette is not well documented. We have also found blue monkeys south into Lusambo, but we are not sure what taxonomic form they represent. Please give us the citation for the Boyela hunters. There are many important discoveries of Congo’s fauna still to be made.

  9. michael
    Posted 2017-10-07 at 8:31 pm | Permalink

    Hello John,

    Hunting of the Boyela, Slash-and-Burn Agriculturalists, in the
    Central Zaire Forest
    SATO, Hiroaki
    African Study Monographs (1983), 4: 1-54

    use the link

    At page 10 cercopithecus mitis is listed under the local name “Bokoma”


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