Boldness traits, not dominance, predict exploratory flight range and homing behaviour in homing pigeons

Abstract

Group living has been proposed to yield benefits that enhance fitness above the level that would be achieved through living as solitary individuals. Dominance hierarchies occur commonly in these social assemblages, and result, by definition, in resources not being evenly distributed between group members. Determinants of rank within a dominance hierarchy can be associated with morphological characteristics, previous experience of the individual, or personality traits such as exploration tendencies. The purpose of this study was to investigate whether greater exploration and positive responses to novel objects in homing pigeons (Columba livia) measured under laboratory conditions were associated with (i) greater initial exploration of the local area around the home loft during spontaneous exploration flights (SEF), (ii) faster and more efficient homing flights when released from further afield, and (iii) whether the traits of greater exploration and more positive responses to novel objects were more likely to be exhibited by the more dominant individuals within the group. There was no relationship between laboratory-based novel object exploration and position within the dominance hierarchy. Pigeons that were neophobic under laboratory conditions did not explore the local area during SEF opportunities. When released from sites further from home, neophobic pigeons took longer routes to home compared to those birds that had not exhibited neophobic traits under laboratory conditions, and had spontaneously explored to a greater extent. The lack of exploration in the neophobic birds is likely to have resulted in the increased costs of homing following release: unfamiliarity with the landscape likely led to the greater distances travelled and less efficient routes taken. Birds that demonstrated a lack of neophobia were not the dominant individuals inside the loft, and thus would have less access to resources such as food and potentially mates. However, a lack of neophobia makes the subordinate position possible, because subordinate birds that incur high travel costs would become calorie restricted and lose condition. Our results address emerging questions linking individual variation in behaviour with energetics and fitness consequences.This article is part of the themed issue 'Physiological determinants of social behaviour in animals'.

Keywords: Columba livia; GPS; dominance hierarchy; navigation; neophobia; personality.

Figure 1.

Simplified representation of floor space of laboratory for personality testing in the pigeons.

Figure 2.

Laboratory-based personality tests in nine homing pigeons versus spontaneous exploration flight (SEF) from the loft. (Left) Novel object score (measured as time spent in respective zone close to novel object, table 1) versus mean (n = 3, full details in electronic supplementary material, table S2) furthest point reached (in metres) during SEF from the home loft. (Middle) Mean furthest point reached during SEF versus latency to approach novel object. (Right) Mean furthest point reached during early exploratory flights versus laboratory-based exploration score. Regression details: (left) r² = 0.66, F = 16.65, p = 0.004, r² = 0.72, F = 21.15, p = 0.002, (middle) r² = 0.50, F = 8.94, p = 0.02, and (right) r² = 0.39, F = 6.06, p = 0.043 (see §3 for regression equations).

Figure 3.

(Left) Mean furthest point reached (metres) during free-choice natural exploration flights versus mean route efficiency in nine homing pigeons. Mean route efficiency (see electronic supplementary material, table S4 for s.e.) versus (middle) novel object score (measured as time spent in respective zone close to novel object, figure 1 and table 1), and (right) exploration score (see §3). Regression details: (left) r² = 0.86, F = 43.72, p = 0.0003, (middle) r² = 0.81, F = 30.80, p = 0.0008, and (right) r² = 0.53, F = 7.96, P = 0.03 (see §3 for regression equations).

Figure 4.

Initial homing flight from release site 2 (electronic supplementary material, table S1). Six pigeon GPS traces are shown: pigeons 1 (green), 2 (black), 4 (yellow), 6 (red), 7 (blue) and 9 (brown). The black triangle denotes the home loft, and the release site is represented by a black square. Route efficiencies are detailed in electronic supplementary material, table S4. Bird 4 did not return home within the battery life of the logger (c. 6 h), and returned approximately 7.5 h following release. Some initial circling has been removed for presentation purposes. Background images taken and owned by UK Ordnance Survey™.

Figure 5.

Initial homing flight from release site 6 (electronic supplementary material, table S1). Six pigeon GPS traces are shown: pigeons 1 (green), 2 (black), 4 (yellow), 6 (red), 7 (blue) and 9 (brown). The black triangle denotes the home loft, and the release site is represented by a black square. Route efficiencies are detailed in electronic supplementary material, table S4. Birds 4 and 9 did not return home within the battery life of the logger (c. 6 h) and did not return until the next day. Some initial circling has been removed for presentation purposes. Background images taken and owned by UK Ordnance Survey™.