After weeks spent packing, moving from our apartment, and traveling, my partner Jack and I have finally arrived in Uganda. Though it will still take some time to get settled into the place we’ll call home for the next year, a currently empty house in western Uganda will soon begin to feel familiar. The notion of a nice place to come home to at the end of a long day in the field sounds very appealing.
We humans are not the only ones to recognize home. For chimpanzees, home typically consists of an area of habitat called their home range, often measured as the area a chimpanzee community travels over a year. Home ranges vary in size across chimpanzee communities, ranging from under 10 km2 to over 50 km2. In eastern chimpanzees—the subspecies I study—females often favor certain parts of their community’s home range. This favored region, called a core area, is where a particular female will spend much of her time feeding and nesting, often with her offspring.
Male chimpanzees, who remain in the community in which they were born through adulthood, come to know their mother’s core area from a young age. Murray and colleagues (DOI: 10.1016/j.cub.2007.11.044) found that males at Gombe National Park, Tanzania continue to visit and forage in their mothers’ core areas even into adulthood, especially when solitary. This suggests that particularly when food is scarce, these males reduce feeding competition and increase foraging efficiency by heading for the old familiar areas they know best.
What is home like for chimpanzees whose habitat is rapidly being altered, however? What space does a female carve out for herself and her offspring when she can scarcely escape the sound of chainsaws? What must it be like for an adult male to try to stop by for a bite to eat at an old favorite tree from childhood, only to find out the tree has been logged? Because habitat loss is a staggering issue for chimpanzees here in Uganda as well as elsewhere, these experiences must be very common. A recent article by numerous great ape researchers (DOI: 10.1111/ddi.12005) attests to the rapid rate of habitat loss for our ape cousins. Every day, chainsaws send favored nesting trees crashing to the ground, humans carve new and altered paths are through fragile forests, and pit saws slice fruiting trees into timber planks.
For the elders in the chimpanzee communities I study, I wonder how they perceive the changes over the course of their lives, which can last up to 50 years or more (DOI: 10.1126/science.1201571). Are they fearful when they awake to the sound of loggers nearby? Do they feel angry about the deterioration of their forest home? Unfortunately, we can never be certain how they feel.
However, Dr. Matthew McLennan, my colleague and soon-to-be next-door neighbor in Uganda, co-authored a fascinating article (DOI: 10.1002/ajp.20839) with Catherine Hill on chimpanzee responses to researchers in Uganda. Their findings suggest these chimpanzees use numerous strategies—including aggression—for dealing with a habitat increasingly disturbed by human presence.
For the youngest chimpanzees, I wonder what the future holds. They have never known life in an undisturbed forest. Will they masterfully adapt to life in a mosaic habitat among their human neighbors? Or will the environmental pressures prove to be too much to handle? Though my research will hopefully help fill in some pieces of the puzzle, much uncertainty remains for our chimpanzee cousins who rely on something called “home” just as we do.
Previously in this series:
Secrets of the Universe: Past, Present, FutureX