Brown Noddy Chick Predation by Great Frigatebirds in the Northwestern Hawaiian Islands

Abstract

Adult female Great Frigatebirds (Fregata minor) were responsible for 64% of the predatory behaviors on Brown Noddy (Anous stolidus) chicks on Tern Island, French Frigate Shoals, Hawaii. Subadults with red orbital rings (presumably females) also preyed on Brown Noddy chicks, although they were observed hunting less frequently than adult females. No adult male frigatebirds were observed hunting in 118.3 hours of observation. Frigatebird predation likely accounted for 95% of mortality observed in Brown Noddy chicks less than 24 days of age. Chicks were as likely to survive to fledging regardless of nest location or down coloration; however, more chicks survived to fledging if hatched between mid-February and mid-May. Unequal sex ratios, sexual size dimorphism, resource partitioning, and breeding strategies of fiigatebirds were evaluated to explain why sex differences in frigatebird predation behaviors were observed on Tern Island.

Differential responses to guano fertilization among tropical tree species with varying functional traits

“…The particular species were chosen because of their dominance in this region and because of the established differences in their degree of association to seabirds. Seabirds are commonly associated with three of these four species (Clark et al, 1990; Megyesi and Griffin, 1996), whereas one species, the coconut palm ( C. nucifera ), provides poor nesting and roosting habitat for seabirds and is thus associated with low seabird abundance (Young et al, 2010a). Given previous observations of the distributional patterns of these four tree species along gradients of tree‐nesting seabird abundance, we hypothesized that (1) the species that is not found in association with seabirds (i.e., C. nucifera) would have functional traits more associated with low‐nutrient, stress‐tolerant strategies (low SLA, low chlorophyll, low foliar nutrients) than would the other seabird‐associated species (i.e., P. grandis , S. sericea , T. argentea ), and (2) C. nucifera would have reduced performance responses (growth, chlorophyll, SLA) to fertilization, but would have similar responses in foliar nutrients.…”

Flight‐initiation response reflects short‐ and long‐term human visits to remote islets

“…In the context of remote islands free of mammalian predators, weak escape behaviour reflected by short FIDs could instead reflect strong defence behaviours (Megyesi & Griffin 1996). Although egg predators exist in our study system (e.g.…”

“…The remoteness of oceanic islands has allowed for the evolution and maintenance of rich and endemic biodiversity, isolated from many pressures including anthropogenic species is considered to be very sensitive to pressures from human visits, native predators and invasive species (Burger & Gochfeld 1988, Megyesi & Griffin 1996, Pandolfi & Bretagnolle 2002, Angel & Cooper 2006. We measured FID of nesting Brown Noddies at three sites during our first visits to account for a potential heterogeneity in the spatial distribution of escape behaviour that could be due to variation in the prevailing human environment.…”

Effect of predation risk and ectoparasitic louse flies on physiological stress condition of the red-tailed tropicbird (Phaethon rubricauda) from Rapa Nui and Salas & Gómez islands

“…A possible explanation for the absence of differences in stress indicators between the two assessed colonies in this study might be related to the presence of the native Great Frigatebird ( Fregatta minor ) in Salas & Gómez. This species is known to kleptoparasitize on several seabird species, including the red-tailed tropicbird, and also is reported to depredate on small seabird chicks ( Schreiber & Ashmole, 1970 ; Megyesi & Griffin, 1996 ). Red-tailed tropicbirds in Salas & Gómez nests under rocky protection, and no exposed nests were observed in this colony.…”