Diversity of migration strategies among great frigatebirds populations

Abstract

Migratory behavior varies extensively between bird taxa, from long distance migration to purely sedentary behavior. Variability in migratory behavior also occurs within taxa, where individuals within some species, or even populations, show mixed strategies. The same variability occurs in seabird species. We examined the migratory behavior of distinct populations of great frigatebirds Fregata minor in three distant oceanographic basins. Great frigatebird populations showed extensive variation in post-breeding migratory behavior. Birds from Europa Island (Mozambique Channel) made longdistance migration to numerous distinct roosting sites in the Indian Ocean, New Caledonia birds made shorter distance migrations to roosting sites in the southwestern Pacific Ocean, and Galapagos birds were resident within the archipelago year round. Juvenile birds from Europa Is. and New Caledonia dispersed widely whereas Galapagos juveniles were resident year round. The migratory behavior of Europa Is. and New Caledonia resulted in complete separation of foraging grounds between breeding adults, non-breeding adults, and juveniles, whereas in the Galapagos the overlap was complete. We suggest that population variability in migratory behavior may have arisen because of different environmental conditions at sea, and also depends on the availability of suitable roosting sites on oceanic islands. The results also highlight the capacity of frigatebirds to remain airborne most of the time even outside the breeding season when they have to molt.

Early arrival at breeding grounds: Causes, costs and a trade‐off with overwintering latitude

“…More broadly, bird migration is a flexible phenomenon (Alerstam, Hedenström, & Åkesson, ; Newton, ), and many species display significant variation in migration flyways between and within populations (e.g. Barbraud, Barbraud, & Barbraud, ; Shamoun‐Baranes, Burant, Loon, Bouten, & Camphuysen, ; Weimerskirch et al., ). Further research on the differences and trade‐offs between migration strategies would advance our knowledge on the evolution and conservation of bird migration.…”

Cyclone avoidance behaviour by foraging seabirds

“…In New Caledonia, 7 great frigatebirds from Walpole Island were fitted with 9.5 g solar-panelled Argos PTTs (duty cycle 12 hON, 12h OFF) in September 2014 and March 2015 46 . When cyclone Pam (category 4) crossed the New Caledonian area on 13–14 March, 4 non-breeding birds were present and foraging from islands around New Caledonia and Vanuatu.…”

Biogeography of Micronekton Assemblages in the Natural Park of the Coral Sea

“…In the New Caledonian Exclusive Economic Zone (EEZ), located in the Coral Sea at the southwestern edge of the Pacific Ocean, top predator diet studies (Young et al, 2010;Allain et al, 2012;Olson et al, 2014;Williams et al, 2014) and trawl data analyses (Grandperrin et al, 1999;Young et al, 2011;Menkes et al, 2015) reveal a high diversity of micronekton organisms (Payri et al, 2019). This high diversity also supports high richness of top predator species (Ceccarelli et al, 2013;Laran et al, 2016) with the presence of several species of cetaceans (Mannocci et al, 2014;Garrigue et al, 2015), sharks (Bakker et al, 2017;Boussarie et al, 2018), seabirds (Borsa et al, , 2015Weimerskirch et al, 2017), and tuna (Roger, 1976(Roger, , 1986. Moreover, the seabed topography is complex around New Caledonia (Gardes et al, 2014) with the presence of three ridges (about 1000 m depth), numerous seamounts with a high shape diversity (summit depth from 1000 to 10 m), one trench (about 6000 m depth), and some sedimentary basins (about 3000 m depth) (Figure 1).…”