Lack of remote monitoring of nests may explain why few Neotropical nest predators are mammals

Knowing the identities of nest predators is critical to fully understand nest predation patterns. In 2014, we conducted a review of nest predation events reported in the Nearctic. Another, more comprehensive review was conducted in 2016 for Neotropical nest predators. A total of 158 and 254 species were identified in each region respectively. The proportion of reptile and arthropod species was similar among the two regions, but relatively less birds (47 v. 56%) and more mammals (34 v. 22%) were identified in the Nearctic. One explanation for this difference lies in the more frequent use of nest remote monitoring techniques in the Nearctic zone, which may mitigate the bias towards diurnal predators that is caused by data gathered by direct observation. In the Nearctic, 30% of all the sources (N = 88) identified nest predators using remote cameras. Together, these studies alone identified 50% of all the mammalian predators. In the Neotropics, only 33 studies (8% of the total) used remote cameras, and they alone identified 20% of all the mammals. Many mammals have nocturnal habits and predators that act at night will very unlikely be witnessed in the act of predation. Thus, apart from its efficiency and reliability, an additional reason for the use of remote monitoring in the Neotropical zone is to specifically compensate for the lack of information on nocturnal nest predators.