Sunday, November 15, 2009

More murrelet musings

Great birds attract lots of birders. Lots of birders tend to talk, and with a great bird to look at, the conversation stays focused right where it should be ... on birds (I read an article once in Bird Watcher's Digest where one of the hawk counters at Lake Erie Metropark correlated lack of birds with increased discussion of sports, politics etc.)
Yesterday I speculated that the bird might be a non-breeding adult based on the extension of black behind the eye cutting off the white extending up behind the ear. Further review of Sibley suggests that a non-breeding adult should still have some white wisps that form the half halo of baldness partly responsible for its name (the other is the contrasting gray mantle which has been compared to the shawl more popular in the fashion of the older demigraphic).

Some of us wondered about the bird's route to matriculation at the University of Tiscornia's Main Campus. My guess was that the bird had flown along the Arctic Ocean, followed the Hudson Bay south and ended up in the Great Lakes. This turns out to be the course surmised by A.C. Bent, one of the more famous ornithologists of the first half of the 20th century. That being said, two authors independently examined weather data in the 1960's following records in Illinois (1) and Montana (2) respectively. Both of them found that most records east of the Rockies correlated with extreme low pressure systems along the Pacific coast associated with very high winds to push migrating birds inland. Clearly the farther east a bird is, the harder it is to try to assign it to a specific weather event. However, here's how the bloggers at describe the first week of November in their neck of the woods: "During the first week of November 2009, a major storm wracked the Oregon and Washington coasts. Wind gusts of up to 90 mph were recorded on some headlands and up to five inches of rain fell in places. On 5 November swells of up to 25 feet were reported off the southern Oregon coast. During and after this onslaught thousands of birds flooded into the sheltered estuaries or rode out the storm grounded on beaches."

The bird's short-term survival was also debated on two fronts. The first is that these birds typically forage in salt water. It's not a tube-nose though, and I don't know that it has any particular physiologic adaptations to salt water that would prohibit its ability to regulate its sodium balance; I certainly didn't find any papers suggesting that anyone has researched the osmolar gradients reached in murrelet kidneys or murrelets' ability to modulate ADH (anti-diuretic hormone) or similar compounds that can affect water resorption in the nephron's collecting duct. What I did find, however, were two papers with indirect evidence that murrelets could survive in fresh water. First a team from Tasmania (3) measured the amount of salt that seabirds (diving petrels and fairy prions) ingest from the salt water versus that ingested in food. They found that sea water accounted from about a quarter of the salt ingested by these tubenosed birds that can probably be more cavalier with how much seawater they ingest. My guess is that decreasing salt intake by a quarter would be easily compensated for by the usual activity of the kidneys. The other paper of interest was one by Hobson (4). He found (also by measuring different isotopes of carbon and nitrogen in the birds) that Marbled Murrelets will sometimes feed in fresh water for up to several weeks at a time.

The other question is one of food. These birds mainly eat krill, which obviously is at quite a premium in the Great Lakes. However, Kaufman (5) notes that in some seasons they eat "mostly very small fish," and indeed the bird was diving actively into the schools of small fish that had accumulated next to the pier (and also attracted good numbers of steelhead as evidenced by the fishermen's success). Once we observed it to surface with a fish about 2 inches long. Generally after 20-30 minutes of diving actively it would work its way back out into the lake and rest. Moreover, Munyer (1) suggested that 2 March records from Lake Erie in 1951 that followed a mini-invasion of sorts with 2 other inland records in November of 1950 in other parts of the country likely represented over-wintering birds.

A few other items of note, several authors (including a review annoted by Bendire (6), as in Bendire's Thrasher) observe that Ancient Murrelet is a favorite food for Peregrines, perhaps contributing to their diurnal habits. Along with those diurnal habits, murrelets are very vocal (one of the bigger surprises for those of us for whom any murrelet was a novelty). They breed in hidden locations in the grasses of islands and the Pacific coast rather than the seabird cliffs favored by some of the other alcids and so have more well developed vocalizations. The birds are so vocal in fact, that the early explorers (6) studying them recorded that "after losing about a week's sleep, owing to their squeaking, I at least felt like choking the whole lot." They describe a "high shrill whistle" used in the breeding burrows and a "peculiar piping whistle" used at sea. I'm not sure how the rhee-eeee-ee notes we heard would be characterized though I think piping would be more accurate than shrill (though it was very high-pitched). My microphone and mini parabolic dish which spent 2 weeks in the back of the truck had unfortunately migrated back to the shelf at home, so no sonograms from me, but extensive sonographic review of the species' vocalizations has been made (7) if others' recordings turned out.

I guess I'm mostly out of thoughts for now (assuming anyone's still reading), other than that the bird might hang out in southern Lake Michigan, will have to keep it in mind while checking the holes in the ice later in the winter.

1. Munyer EA. Inland Wanderings of the Ancient Murrelet. Wilson Bulletin 77:3. 1965.
2. Verbeek NAM. Wanderings of the Ancient Murrelet: Some Additional Comments. Condor 68:5. 1966.
3. Green B and N Brothers. Water and Sodium Turnover and Estimated Food Consumption Rates in Free-living Fairy Prions (Pachyptila turtur) and Common Diving Petrels (Pelecanoides urinatrix). Physiological Zoology 62:3. 1989.
4. Hobson KA. Stable Isotope Analysis of Marbled Murrelets: Evidence for Freshwater Feeding and Determination of Trophic Level. Condor 92:4. 1990.
5. Kaufman K. Lives of North American Birds. Houghton-Mifflin, New York, NY. 1996. p277.
6. Bendire, C. Notes on the Ancient Murrelet (Synthli-boramphus antiquus), by Chase Littlejohn With Annotations. Auk 12:3. 1895.
7. Jones IL, JB Falls, and AJ Gaston. The Vocal Repertoire of the Ancient Murrelet. Condor 91:3. 1989

1 comment:

Cathy Carroll said...


Impressive post with some very thoughtful musings. Thanks for taking the time to research and write this.