Small birds (sparrows, robins, jays, finches) and mammals (squirrels, rats, opossums, raccoons) are a common sight in many urban and suburban communities with green space. However, I observe carcasses of these animals relatively infrequently.

I imagine that the following are some of the most common causes of death:

* Predation (the species I mention are small, and somewhere in the middle of the food chain)
* Age-associated decline in foraging ability, leading to starvation
* Disease
* Fatal contact with infrastructure (collisions with buildings or wind turbines, contact with electricity lines)

I can think of two reasons why we don't see carcasses very often:

* predation is the most common cause of death
* individuals that succumb to disease/starvation end up in their nests/dens

Is this plausible? Has this been studied systematically, e.g. in populations of birds with tracking bands?