Neotropical birds and mammals show divergent behaviour responses to human pressure

Human presence and habitat disturbance (together human pressure hereafter) can generate a deep fear in animals and this can influence their behaviour. Altered animal behaviour, such as shifts in diel activity patterns, affect many species and species interactions, which can induce changes in individual fitness, species-level population persistence, evolutionary dynamics, and ecosystem-level biodiversity. However, whether dial activity behavioural responses to human pressure are consistent among key functional groups has been poorly studied. For example, while medium to large mammal species tend to become more nocturnal in areas with high human pressure, its unclear if sympatric/co-occurring birds display similar or opposite patterns. This is an important knowledge gap because synchronous or opposing guild-level shifts can shape consequences for food-web dynamics (predation and competition), stability of interaction networks and ecosystem functioning. Here we used information from camera trapping along a gradient of human pressure in the Colombian Llanos region to assess diel activity changes in birds and mammals. We found that the diel activity of over 45% of the bird and 50% of the mammals assessed significantly changed where there was higher human pressures, with mammals becoming more nocturnal and birds more diurnal. The opposing behavioural responses to humans among vertebrate functional groups has significant repercussions for the fields of community ecology, including intraguild predation and competition, and may be a significant ecosystem-level conservation consideration.