Well, we didn’t actually get to Isla de Pajaros in Bocas del Toro. It’s a pity, as it’s a pretty dang awesome place (I mean, birds! Lots of birds! It must be that system pride thing, but it’s acceptable because they’re also dinosaurs). I’d planned a bit of a babble on the seabirds there, and it seemed an alright topic for a blog post.
So, check out this lovely rock!
At this site, we could’ve seen Red-billed tropicbirds, Magnificent Frigatebirds (up close!), and brown boobies with babies (oh, come on! Sure, birds get common names that sound mildly inappropriate, but…).
We have seen Magnificent Frigatebirds- perhaps the only seabird that is strongly sexually dimorphic (and, interestingly, females tend to breed every other year due to long post-hatching care of the young while males breed more frequently, thus they don’t really have that long-term pair bond thing going (seabirds tend to have lowish EPC rates and high fidelity (at least to the site))- fairly regularly during this course (they’re the big ones that sort of look like the mental image of a pterodactyl in flight (apparently they can remain aloft for days while they forage)). These birds are rather well known for their kleptoparasitic behavior, attacking other seabirds and stealing prey, although it may not make up a significant portion of their diet (Vickery and Brooke 1994). When not stealing hard-won fish from boobies (okay, fine, you are allowed to laugh it out…), frigatebirds feed on fish and squid at the surface (apparently a soggy frigatebird is a drowning frigatebird, they rarely deign to touch the waves).
Seabirds tend to live long (37+ year old frigatebirds for example, and that 63 year old Laysan Albatross (the oldest known bird in the Northern Hemisphere) that was still raising chicks on Midway), reach sexual maturity late, usually have a single egg (or siblicide that will bring the number of chicks down to one in the end), and extended parental care. At least in some more temperate zone breeding seabirds, if forage fish drop below a certain abundance threshold (one-third of maximum biomass recorded) then seabird productivity is consistently reduced (Cury et al. 2011). As these birds tend to breed once a year (or once every other year in some cases), reduced productivity isn’t something to sneeze at.
When you all next head back to visit Bocas del Toro, please swing by to Isla de Pajaros and say hi to the seabirds!