Oriental Turtle Dove (Streptopelia orientalis) Science Article 2
In many bird species, nest predation is one of the most significant causes of breeding failure (Ricklefs 1969). Breeding density is often considered to affect nest predation. Higher breeding density often results in lower predation pressure for species which will mob nest predators (Berg et al. 1992, Westneat 1992). Alternatively, in species which build cryptic nests and do not attack nest predators, nest predation tends to be higherwhen nesting density is high.
Takesh Wada, The Condor 96:812-816