D Owen 1995; Stewart 1997; Catry et al. 2004; Duijns et al. 2014) including seabirds (Croxall et al. 2005; Phillips et al. 2009, 2011), but examples in monomorphic species are rare (Bogdanova et al. 2011; Guilford et al. 2012; M ler et al. 2014) and the causes behind the segregation are unclear. Although we did not find anyFayet et al. ?Drivers of dispersive migration in birds(a)4 21 3 rstb.2013.0181 19 16 2 82 78 75foraging sitting on the water sustained flightlo c al A tl a n tic A tl a ntic + M e d(b) daily energy expenditureDEE (kJ/day)(c) sustained flying 0.1 local Atlantic Atl + Medproportion of time/month0.08 0.06 0.04 0.021170 1070local : Atlantic local : Atl + Med Atlantic : Atl + Med (d) foraging 0.proportion of time/month* *** ** ** *** ** ** * ** *** ** *** *(e) sitting on the water surfaceproportion of time/month1 0.9 0.8 0.7 0.0.0.0.05 Aug Sep Oct Nov Dec Jan Feb MarAug SepOct Nov Dec JanFeb Marlocal : Atlantic local : Atl + Med Atlantic : Atl + Med***** ** *** ** ** ** *Figure 5 Activity budgets and Silmitasertib cost Average DEE for different types of routes, for the “local” (dark green), “Atlantic” (light green), and “Atlantic + Mediterranean” routes (yellow). The “local + Mediterranean” route is not included because of jir.2014.0001 small sample size (n = 3). (a) Average winter activity budget for the 3 main routes. (b ) Monthly average of (b) DEE and time budget of (c) sustained flight, (d) foraging, and (e) sitting on the surface for the 3 main types of routes. Means ?SE. The asterisks under the x axis CX-4945 represent significant differences (P < 0.05) between 2 routes (exact P values in Supplementary Table S2).sex differences between sexually monomorphic puffins following different types of routes, we found some spatial sex segregation and sex differences in the birds' distance from the colony. On average, the overlap between males and females was considerable during the first 2? months of migration but then sharply decreased, leading to substantial spatial sex segregation from November onwards. Apart from prelaying exodus in procellariiformes (Warham 1990) and occasional prebreeding trips to the mid-Atlantic in male blacklegged kittiwakes Rissa tridactyla (Bogdanova et al. 2011), sex segregation in seabirds, and in migratory species in general, usually occurs either throughout the entire nonbreeding period (Brown et al. 1995; Stewart 1997; Marra and Holmes 2001; Phillips et al. 2011) or not at all (Guilford et al. 2009; Egevang et al. 2010; Heddet al. 2012; Stenhouse et al. 2012). The winter diet of adult puffins is poorly known, but there seems to be no clear partitioning between sexes (Harris et al. 2015), while sexual monomorphism makes size-related segregation by dominance unlikely (Harris and Wanless 2011). To our knowledge, this is the first time that winter sex segregation of such extent is reported in auks, but the mechanisms behind such differences remain unclear and need further investigation. Lastly, we explored the potential of intraspecific competition to drive dispersive migration. Competition for local resources leading to low-quality individuals migrating further is thought to cause differential migration in several avian species (Owen and Dix 1986; Carbone and Owen 1995; Gunnarsson et al. 2005;Behavioral EcologyBogdanova et al. 2011). Alternatively, distant productive areas in the Atlantic or the Mediterranean Sea may only be reachable by high-quality birds. Both alternatives should lead to fitness differences between routes (Alve.D Owen 1995; Stewart 1997; Catry et al. 2004; Duijns et al. 2014) including seabirds (Croxall et al. 2005; Phillips et al. 2009, 2011), but examples in monomorphic species are rare (Bogdanova et al. 2011; Guilford et al. 2012; M ler et al. 2014) and the causes behind the segregation are unclear. Although we did not find anyFayet et al. ?Drivers of dispersive migration in birds(a)4 21 3 rstb.2013.0181 19 16 2 82 78 75foraging sitting on the water sustained flightlo c al A tl a n tic A tl a ntic + M e d(b) daily energy expenditureDEE (kJ/day)(c) sustained flying 0.1 local Atlantic Atl + Medproportion of time/month0.08 0.06 0.04 0.021170 1070local : Atlantic local : Atl + Med Atlantic : Atl + Med (d) foraging 0.proportion of time/month* *** ** ** *** ** ** * ** *** ** *** *(e) sitting on the water surfaceproportion of time/month1 0.9 0.8 0.7 0.0.0.0.05 Aug Sep Oct Nov Dec Jan Feb MarAug SepOct Nov Dec JanFeb Marlocal : Atlantic local : Atl + Med Atlantic : Atl + Med***** ** *** ** ** ** *Figure 5 Activity budgets and average DEE for different types of routes, for the “local” (dark green), “Atlantic” (light green), and “Atlantic + Mediterranean” routes (yellow). The “local + Mediterranean” route is not included because of jir.2014.0001 small sample size (n = 3). (a) Average winter activity budget for the 3 main routes. (b ) Monthly average of (b) DEE and time budget of (c) sustained flight, (d) foraging, and (e) sitting on the surface for the 3 main types of routes. Means ?SE. The asterisks under the x axis represent significant differences (P < 0.05) between 2 routes (exact P values in Supplementary Table S2).sex differences between sexually monomorphic puffins following different types of routes, we found some spatial sex segregation and sex differences in the birds' distance from the colony. On average, the overlap between males and females was considerable during the first 2? months of migration but then sharply decreased, leading to substantial spatial sex segregation from November onwards. Apart from prelaying exodus in procellariiformes (Warham 1990) and occasional prebreeding trips to the mid-Atlantic in male blacklegged kittiwakes Rissa tridactyla (Bogdanova et al. 2011), sex segregation in seabirds, and in migratory species in general, usually occurs either throughout the entire nonbreeding period (Brown et al. 1995; Stewart 1997; Marra and Holmes 2001; Phillips et al. 2011) or not at all (Guilford et al. 2009; Egevang et al. 2010; Heddet al. 2012; Stenhouse et al. 2012). The winter diet of adult puffins is poorly known, but there seems to be no clear partitioning between sexes (Harris et al. 2015), while sexual monomorphism makes size-related segregation by dominance unlikely (Harris and Wanless 2011). To our knowledge, this is the first time that winter sex segregation of such extent is reported in auks, but the mechanisms behind such differences remain unclear and need further investigation. Lastly, we explored the potential of intraspecific competition to drive dispersive migration. Competition for local resources leading to low-quality individuals migrating further is thought to cause differential migration in several avian species (Owen and Dix 1986; Carbone and Owen 1995; Gunnarsson et al. 2005;Behavioral EcologyBogdanova et al. 2011). Alternatively, distant productive areas in the Atlantic or the Mediterranean Sea may only be reachable by high-quality birds. Both alternatives should lead to fitness differences between routes (Alve.