I was reading Tupai: A Field Study of Bornean Treeshrews by Louise H. Emmons because that is the kind of thing I like, and learned about the absentee maternal system found in some treeshrew species.
First I should say that treeshrews are the same as tree shrews, and the closing up of the word is probably meant to indicate that they don't really live in trees and they're not really shrews. This is a case of TC, Taxonomic Correctness, like the argument that you should call a starfish a sea star because it's not really a fish. Oh please. But a big issue about treeshrews is whether they're descended from very primitive primates and so are our distant cousins, or whether the connection goes further back so that the primates and the treeshrews are both descended from the clade Euarchonta, making them even more distant cousins. I have no opinion on this.
In the absentee maternal system the mother treeshrew builds two nests (yeah, in trees). They are far apart. She puts her babies in one and she sleeps in the other one when she's not racing around snuffling through the leaf litter and catching bugs. Every other day she secretly visits the babies, taking a different route each time, and nurses them. When she's not there the babies lie still and don't make a sound. If an intrepid wildlife biologist like Louise H. Emmons takes a baby out of the nest, it lies silently in her hand with its eyes closed.
One day when they are old enough the mother treeshrew drops by as usual, but instead of just nursing them she takes them out and shows them Borneo. Here's a bug, here's a little trail, here's what you do when you hear a scary noise -- there's another bug! Let me see you grab it! She brings them with her on her rounds and protects them while they learn the business of treeshrewing.
According to a report from the wild, the babies were "shaky" the first time they came out of the nest hole.
The reason treeshrews do this has to be that it makes it much less likely that predators will find the nest and eat the babies by observing the mother. (That's the sort of creepy trick that jays and crows do, for example.) And obviously it's very convenient for the mother treeshrew. Which makes me lean toward the idea that treeshrews aren't primates – what baby primate holds that still for that long?
Like other wildlife biologists who write books for general audiences, Louise H. Emmons tries to find a balance between the stuff working scientists mostly do, and the stuff that people are actually interested in hearing about. Most of the work of wildlife biology doesn't involve playing peekaboo with baby gorillas, swimming with whale sharks, or filming hippo hijinks. It involves data sets. Perhaps Emmons leans too far in the direction of hard science, because her best story was walled up alive in an appendix. (I read appendices so you don't have to. Or at least I skim them.)
In Appendix 1, Emmons explains why a trapping data set is incomplete.
In the January trapping period, a group of elephants went through the study area, systematically destroying man-made objects (rain gauges, signs, trail markers, etc.). They stomped on seven baited traps but interestingly did not step on one that contained a treeshrew, while flattening the two on each side (trapping in January was curtailed, and this month is excluded from most data).
The elephants spared the tiny prisoner! Of course I think they did it because they felt compassion for the treeshrew, but I realize that there is also a compelling quality to the explanation that they did it because they didn't want to get their feet sticky.