Dusky flycatcher (Empidonax oberholseri) nest at the Mount Haggin Wildlife Management Area, Montana.

Defensive traits and their indirect demographic costs vary among species

Many animal species have behavioral responses to perceived predation risk, but these responses can cause indirect demographic costs like reduced survival or reproductive output later in life.  My dissertation work has revealed why prey species differ in their behavioral responses to generalist enemies, like nest predators, and the resulting indirect demographic costs from those responses.  Using data collected from over 1,000 nests in combination with experimental manipulation of perceived predation risk, I found that 10 bird species differed widely in behavioral responses to increased perceived predation risk and resulting indirect costs (LaManna & Martin 2016 Ecology Letters).  These differences were associated with variation in residual-reproductive value across species.  Individual-based demographic models revealed that these indirect-demographic costs actually outweighed the demographic costs from direct predator consumption for some but not all species (LaManna & Martin 2017 Ecology).

Dusky Flycatcher (Empidonax oberholseri) brooding her young near Tenderfoot Creek, Lewis & Clark National Forest, Montana.

Red squirrel (Tamiasciurus hudsonicus), a typical nest predator in aspen and conifer forests of western Montana.