Jul. 7, 2009 by Judy
The Owl and the Mosquito
A few nights ago my neighbor popped his head up over the cinderblock wall between our houses and yelled for me to come see the owl pellet that he’d discovered in his breezeway. It seems a barn owl has decided to take up residence somewhere around his house, or mine, and is making a good living from the usual urban fare: rats and mice.
It’s worth noting that there were no barn owls, rats or mice here before about 2000 years ago when the people arrived. There was nothing with four legs at all, in fact, on the land. But there were, and still are, owls. Some scholarly papers say the native owls came after the people did, and some say they were already here, though maybe more recently than some of the really diversified endemics (makes sense). Most of the birdy types I know seem to believe the latter, so I’m going to run with that for now, if that’s OK with you.
Our native owl is called the Short-eared Owl if you’re used to western terms. To Hawaiians, the owl is called Pueo. Most scientists currently agree that this is a descendent of a common owl of the Americas—though whether it’s a subspecies in Hawaii or not is still being decided. If you’re on Maui you can often see the pueo weaving above upcountry pastures. Open fields are mice snacklands, and our native owl is a day flier and ground-nester. These pastures are found generally up around 3,000ft. or so in elevation, where the air is cooler and moister and the lower levels of the usual cloud ceiling can drape sudden mists on the grass.
This blog is not going to be about the native owl, but if you are burning with desire now to know more about it, here’s a nice link with a lovely photo and good basic info:
Anyway, birders who are on the search for other native Hawaiian birds are not likely to find any below this elevation, seabirds/shorebirds excluded. The native bird fauna is more likely found above the 7,000ft. elevation line, and there’s a reason for this: mosquitos.
When the New England whalers and missionaries began arriving here in the early 1800s (with the whalers getting in first), the journey was long and arduous. There was no Panama Canal then, so coming to Hawaii from New England required going all the way down one side of the Americas, then around the bottom tip (with much heaving of seas and stomachs), then coming halfway up the other side of the Americas and THEN heading west to “The Sandwich Islands”. Maui is at roughly the same latitude as Cabo San Lucas, if that helps you orient your head. Anyway, this was a journey of many months (causing pregnancy in more than a few newlywed missionary couples) and necessitated the stopping and getting of fresh water many times from the various Americas. Water, carried in barrels, could carry many things in it. Some of this water carried mosquito larva. Water barrels washed out in Hawaiian wetlands and streams released these larva, and thus began Stage One of Lowland Native Bird Knockout.
Stage Two came when people began bringing, as they seem prone to do, birds with them from their various homelands to Hawaii. They brought birds with lovely songs (Melodious Laughing Thrush, China), birds with gorgeous plumage (too many to name, but look out your window for bright red Northern Cardinals), birds with the ability to knock back crop pests (the extremely aggressive and bright Indian Mynah), and birds that were just familiar and comforting (lots). Pile onto that assortment another layer of birds for eating (chickens, turkeys, partridges, quail, etc.). Hidden in the bloodstreams of these birds were avian diseases like pox and malaria (bird malaria) that these species had learned to live with over time. They’d overcome, they’d moved on, and tiny virulent particles circled around in their bloodstreams with not much to do…but wait for a way to get out and find new hosts.
Can you guess how they got out? I bet you can.
Avian pox and malaria as spread by mosquitos between native and non-native birds, as well as new and overwhelming competition for food and nesting sites, have created a dynamic in which native birds are generally no longer found where the mosquitos are, and here in Hawaii that means from about sea level to about 7,000ft. On Maui, that means you start getting into good native bird habitat right around the entrance to Haleakala National Park. When you enter the park, take your first left into Hosmer Grove and go birding. Give my aloha to the I’iwi. I spend my time at sea level now and I miss those crimson beauties with their decurved bills and their liquid calls.
The pueo seems somehow more resistant to these pox/malaria issues, something that is still a bit of a mystery but a mystery we’re glad to have.
Meanwhile, down here in the seaside suburbs, the much larger, white-faced and nocturnal barn owl seems to have settled in. I’m OK with it mostly because I don’t think the upland pueo misses out on too much by having the newcomers (apparently not bearing deadly microbes) hang out down here and keep the rats and mice in check, and there doesn’t seem to be that much direct competition for food and nesting sites—pueo numbers seem stable. The way I see it, every ball of indigestible fur and bones yakked up in my neighbor’s breezeway is one less predator on the seabirds that nest, so vulnerably, in burrows in the dunes just down the street.
I’ll get to the seabirds next time. For now, keep your eyes on the upland meadows for that familiar, owly swoop of grace and consider this from the site http://www.botany.hawaii.edu/GradStud/pang/pueo.htm:
The Pueo, or Hawaiian Owl (Asio flammeus sandwicensis) is considered sacred by many Hawaiians. It is one of the many physical manifestations (kinolau) of ancestral guardians ('aumakua).The pueo is one of the more widely recognized of the Hawaiian (`aumakua). These birds protect individuals from harm, and even death. One `aumakua from Maui, Pueonuiakea, guides individuals safely back to their home.