Kaiser Marbled Murrelet

Little Lord of British Columbia's Fiords
1. Auflage 2012
ISBN: 978-1-62309-207-8
Verlag: BookBaby
Format: EPUB
Kopierschutz: Adobe DRM (»Systemvoraussetzungen)

E-Book, Englisch, 130 Seiten

This book tracks our changing perception of the Marbled Murrelet from its historic status as an obscure seabird of the North Pacific, through its role as a flagship species for old-growth forest-conservation movements, to a realization that it is a truly amazing bird. It flies faster, commutes further, and lays a bigger egg than any of its neighbours and is the only species to have colonized the forbidding fiords of Canada's west coast. Fifteen thousand years ago, it successfully exploited the last great bout of global warming at the end of the last ice age but may fall victim to the effects of ongoing climate change.

Autoren/Hrsg.

Kaiser, Gary

Leseproben

Figure Captions
Introduction Fig. 0.1 - Two adult Marbled Murrelets in breeding plumage. There are many similar images on the internet that are useful in understanding the bird’s appearance. Few tell us much about the birds biology, but see Fig. 2.3, 3.8. Photo by Norman Holmes. Chapter 1 Fig. 1.1a - Marbled Murrelet skins from the late 19th century and early 20th century in the Royal BC Museum. Most of these birds were collected during the duck-hunting season and are in winter plumage. Only the bird at the bottom right is clearly a juvenile. Fig. 1.1b - Marbled Murrelet skins from the mid- to late-20th century in the Royal BC Museum. These were collected at all seasons and eight or nine are juvenile birds. Fig. 1.1c - Marbled Murrelet skins from the end of the 20th century in the Royal BC Museum. The small bird at the centre is a failed fledgling and several others are identified as victims of accidents. Specimens in the bottom row are “Power Skins” that allow full examination of the plumage and the preparation of a nearly complete skeleton. Fig. 1.2 - Captain Markham’s flagship, H.M.S. Triumph, at Esquimalt Harbour ca. 1870. Image A-00272 Courtesy of Royal BC Museum, BC Archives. Fig. 1.3 - Pebbles from the beach. Boxes of eggs at the Royal BC Museum with no data and no scientific value. They are used for educational purposes. Fig. 1.4 - Cox Island, west of Langara Island at the north tip of Haida Gwaii. Solomon John Darcus claimed to have collected Marbled Murrelet eggs here in 1926. In 1995, the island still housed a colony of Tufted Puffins and perhaps a few Ancient Murrelets. Photo by Solomon John Darcus, 1926. Fig. 1.5 - Ancient Murrelet eggs possibly collected by Rev. C.J. Young or S.J. Darcus. Both were on Langara Island in 1926. Royal BC Museum E1435. Map 1.1 - The coast of British Columbia with some of the place names mentioned in the text. Map 1.2 - Langara, Cox, and Lucy islands at the north end of Haida Gwaii. The coloured areas track the loss of seabirds after the introduction of Norway rats during World War II. Once the rats were exterminated in 1995, the remaining colonies began to recover but those in the south now lie under fishing lodges. Chapter 2 Fig. 2.1 - The skull of a Marbled Murrelet. In spite of the thin bones supporting the beak, the bird is able to catch and hold surprisingly large fish. Fig. 2.2 - Relative positions of the brain (pink) and eyes (blue) in the skull of a Marbled Murrelet. Fig. 2.3a - Sand lance boil to the surface in shallow water beside a bed of kelp. Photo by Mark Cunnington. Fig. 2.3b - Moments later a Marbled Murrelet appears. It is not carrying a fish but these sand lance are less than 6 months old in June and easy for the bird to swallow underwater. Photo by Mark Cunnington. Fig. 2.3c - The Marbled Murrelet seems to lose interest and swims away. It had no fishing buddy and may not have needed one in shallow water. Photo by Mark Cunnington. Fig. 2.3d - A Glaucous-winged Gull is quick to exploit the opportunity and grabs two fish before the swarm can regain their composure. Photo by Mark Cunnington. Fig. 2.4 - A murrelet wing in the partially folded position used during underwater locomotion. The inset photograph shows one wing extended, as it would be in aerial flight (1-cm grid). In both cases, the A-B line follows the axis of the humerus. Fig. 2.5 - Underwing of a soft-winged, forest bird (Clark’s Nutcracker) and a stiff-winged seabird (Marbled Murrelet) showing the relative lengths of the underwing coverts. Fig. 2.6 - Hip bones of the Marbled Murrelet. The long, flexible pubic bones support the abdomen without hindering the egg. The glycogen body is thought to be an organ of balance. Fig. 2.7 - Egg and abdominal skeleton of a Xantu’s Murrelet. The bird and its egg are similar in size and shape to the Marbled Murrelet. Long, flexible ribs and pubic bones shield the sides of the egg while it is developing but do not hinder its passage through the oviduct at laying. Fig. 2.8 - A cross-section through the hip bone of a Marbled Murrelet. The spinal cord is shown in blue. The glycogen body is thought to be an organ of balance. Fig. 2.9 - Adult Marbled Murrelet in breeding plumage. Modern digital cameras make it possible to capture important aspects of behaviour. In this case, the large muscles in the hips have thrust the webbed feet into the water with enough force to lift the bird from the surface and push it far enough into the air that the wing tips do not dip into the water. Photo by Mike Danzenbaker. Fig. 2.10 - Two views of a Marbled Murrelet’s humerus showing the discrepancy between the bone’s width and thickness. Widening in one direction is typical of wing-propelled diving birds. Fig. 2.11 - Two views of an American Crow’s humerus. The width is much the same as thickness, as it is in the great majority of birds. Fig. 2.12 - Cross-sectional images of wing bones in two shearwaters. The species that dives underwater (P. griseus) has a flatter humerus than the one that does not (C. diomedea). Adapted from CT scans by Erin Simons 2009. Chapter 3 Fig. 3.1 - A nearly complete Marbled Murrelet egg found on the forest floor. The opposite side is completely missing suggesting that it was attacked by a predator. Royal BC Museum E2408. Fig. 3.2 - The big end of a Marbled Murrelet egg found on the forest floor. The completeness of this end is typical of eggs that have hatched successfully. Royal BC Museum E2401. Fig. 3.3 - An Ancient Murrelet nesting beneath a grass tussock on Talan Island, near Magadan at the north end of the Sea of Okhotsk. Permafrost discourages the use of burrows. Photo by A. Ya. Kondratyev. Fig. 3.4 - Moss pads on shoreline conifers in Haida Gwaii. Fig. 3.5 - Comparison of the skeletons of adult and fledgling Tufted Puffins. Although the fledgling weighed only 60 percent as much as the adult, the wing bones are very similar in size. The breastbones are very different; that of the younger bird is only partially developed and the entire post-sternal plate is missing. Fig. 3.6 - The fledgling Marbled Murrelet raised from an egg at Simon Fraser University. Two egg teeth are visible, one on the upper beak and a small one beneath the tip of the lower mandible. Photo by Gustavo Londoño. Fig. 3.7 - Breast plumage of a juvenile Marbled Murrelet (left) and an adult (right) showing the relative size of the dark tips on the feathers. Fig. 3.8 - Fledgling Marbled Murrelet at Mitlenatch Island, holding a full-grown, first-year sand lance in late August 2004. Photo by Norman Holmes. Fig. 3.9 - With a toss of its head the murrelet swallows its fish headfirst, see Fig 3.8. Photo by Norman Holmes. Fig. 3.10 - Preserved skin of an albino Marbled Murrelet collected on the north coast of British Columbia on 19 August 1936 (RBCM 6023). The bird is a juvenile that had probably fledged six weeks earlier. Albino birds tend to attract the attention of both natural predators and museum collectors and few are lucky enough to reach adulthood. Scientifically they are usually mere curiosities that tell us little about the biology of their species. Fig. 3.11 - The outermost secondary feather on the wing of a Marbled Murrelet. The tip is strongly asymmetrical and perhaps the only truly specialized feather on the wing. Fig. 3.12 - Sketches of the tips of outermost secondaries from Marbled Murrelets banded in Desolation Sound, 18-19 June 1998. All of these birds had brood patches and were presumed to be breeding. Feather B belonged to a bird with an unusually small brood patch. It also has an unusual line of white dots near the tip and the tip seems fresh and sharp-edged. All of the other examples show significant fraying and wear on the outer edge. Fig. 3.13 - Radar image of Khutze Inlet in June 2001. The M.V. Affinity I is anchored in the estuary near the centre of the screen and a Marbled Murrelet is crossing the inlet more than a kilometer away. The signal is quite strong but there are gaps that might have been caused by the murrelet presenting a very small target when its wings were aligned with the radar signal. Fig. 3.14 - M.V. Affinity I carrying the large radar antenna used for tracking Marbled Murrelets. Photo by Norman Holmes. Map 3.1 Records of very large concentrations of Marbled Murrelets in the Strait of Georgia. The two northernmost are among the very few autumn records. Map...