Sex, personality and conspecific density influence natal dispersal with lifetime fitness consequences in urban and rural burrowing owls

Abstract

There is a growing need to understand how species respond to habitat changes and the potential key role played by natal dispersal in population dynamics, structure and gene flow. However, few studies have explored differences in this process between conspecifics living in natural habitats and those inhabiting landscapes highly transformed by humans, such as cities. Here, we investigate how individual traits and social characteristics can influence the natal dispersal decisions of burrowing owls (Athene cunicularia) living in urban and rural areas, as well as the consequences in terms of reproductive success and apparent survival. We found short dispersal movements among individuals, with differences between urban and rural birds (i.e., the former covering shorter distances than the latter), maybe because of the higher conspecific density of urban compared to rural areas. Moreover, we found that urban and rural females as well as bold individuals (i.e., individuals with shorter flight initiation distance) exhibited longer dispersal distances than their counterparts. These dispersal decisions have effects on individual fitness. Individuals traveling longer distances increased their reproductive prospects (productivity during the first breeding attempt, and long term productivity). However, the apparent survival of females decreased when they dispersed farther from their natal territory. Although further research is needed to properly understand the ecological and evolutionary consequences of dispersal patterns in transformed habitats, our results provide information about the drivers and the consequences of the restricted natal movements of this species, which may explain its population structuring through restricted gene flow between and within urban and rural areas.

Fig 1

A) Natal dispersal distances of urban and rural burrowing owls Athene cunicularia (males: gray bars; females: black bars). The inserted figure shows a detailed distribution of dispersal distances lower than 1km. B) Relationship between natal dispersal distances (log-transformed) and individual personality (measured as FID, flight initiation distance). Lines show the tendency observed for males (gray line) and females (black line). Dashed lines represent the 95% confidence interval. Dots are raw data (males: gray dots, females: black dots).

Fig 2. Relationship between natal dispersal and survival probabilities of male (gray lines) and female (black lines) burrowing owls Athene cunicularia.

Solid lines represent the general tendency obtained using the first model shown in Table 5; dashed lines: 95% confidence intervals.