Fig 1.
Kernel Utilization Distributions (UDs) of female (blue) and male (red) brown (BRBO) and red-footed (RFBO) boobies, tracked between November 2018 –October 2019 at Raso Islet (star), Cabo Verde.
Bathymetric relief in the background (max. 4012m). Shaded area highlights the period when BRBO and RFBO co-occur in sympatry.
Table 1.
Summary statistics (mean±SD, range in brackets) of trip characteristics, spatial distribution, trophic ecology and body condition of tracked brown (BRBO) and red-footed (RFBO) boobies from Raso Islet, Cabo Verde.
Fig 2.
Population-level (Rpop.; black) and individual-level (Rind) repeatability values (±SE) of behavioural parameters for female (blue) and male (red) brown (BRBO) and red-footed (RFBO) boobies.
Shaded area highlights the period when BRBO and RFBO co-occur in sympatry at Raso Islet, Cabo Verde.
Fig 3.
Response curves of the most important smooths resulting from generalized additive mixed models (GAMMs), explaining the foraging distribution of male (red) and female (blue) brown boobies (BRBO) and red-footed boobies (RFBO), during November–May and June–October.
Shaded area highlights the period when BRBO and RFBO co-occur in sympatry at Raso Islet, Cabo Verde.
Table 2.
Generalized Additive Mixed Models (GAMMs) fitted to the probability to switch between foraging (1) and travelling (0) behavioural modes of tracked individual birds.
Table 3.
A. Generalized Linear Mixed Models (GLMMs) testing the effect of (A) the interaction between sex and season (November-May vs. June-October) and (B) the interaction between sex and species (brown boobies-BRBO vs. red-footed boobies-RFBO) on trip characteristics, spatial distribution, trophic ecology and body condition shown in Table 1.
Table 4.
Observed and randomized overlap (Bhattacharyya’s Affinity) at the 50% and 95% Kernel utilization distributions (UDs) between (A) female and male brown boobies during November–May and June–October and (B) female and male brown (BRBO) and red-footed boobies (RFBO) during June–October.
Fig 4.
Estimated proportions of main prey items in the diet of male and female brown boobies (BRBO) and red-footed boobies (RFBO) from Raso Islet, Cabo Verde during a phase when only brown boobies occur on the colony (November-May; left panels) and when the two species co-occur in sympatry (June-October; right panels).
Epipelagic fish–Sardinella aurita, Platybelone lovii, Sardinella maderensis, Selar crumenophthalmus, Cephalopholis taeniops, Cheilopogon sp., Sparisoma cretense, Decapterus macarellus, Myripristis jacobu; Juvenile fish–young fingerlings of epipelagic species; Squid–specimens from the Ommastrephidae and Onychoteuthidae families.