Treesearch

We describe a method for localizing and comparing relative amounts of plasma membrane-associated calcium ions (mCa) in complex tissues and verify the procedure for mesophyll cells of red spruce (Picea rubens Sarg.) needles. This technique incorporates epifluorescence microscopy using the fluorescent probe chlorotetracycline (CTC) with computer image processing and analysis. Using an appropriate standardization for image brightness, the procedure allows relative quantitative comparison of CTC-fluorescence in the plasma membrane-cell wall region that corresponds to relative amounts of mCa....

Tape playback of the staccato song of the Boreal Owl (Aegolius funereus richardsoni) proved useful in attracting fledglings of both North American Aegolius species. No Boreal Owl nests were found in 8 hours of daytime searches. However, six Boreal Owls, including three to four fledglings at two locations, one Northern Saw-whet Owl (A. acadicus) fledgling, and an unidentified Aegolius responded to tape playback in 16 hours of systematic surveys during the post-fledging period (15 July to 30 August) of 1992 and 1993 in habitat known to be occupied by Boreal Owls. This method is considerably...

We examined the pattern of seasonal variation in total foliar calcium (Ca) pools and plasma membrane-associated Ca (mCa) in mesophyll cells of current-year and 1-year-old needles of red spruce (Picea rubens Sarg.) and the relationship between mCa and total foliar Ca on an individual plant and seasonal basis. Foliar samples were collected from seedlings and analyzed on 16 dates at 2- to 3-week intervals between June 1994 and March 1995. Concentrations of mCa in current-year needles were more seasonally dynamic and responsive to temporal environmental changes than either mCa concentrations...

Snowy Owls (Nyctea scandiaca) wintering at Logan International Airport were studied over the 15-year period of 1981-1997. Two-hundred twenty-seven Snowy Owls were banded and color-marked to examine the length of time individual birds stayed at this location and to track the movements elsewhere. Fifty-six owls were re-observed outside of the airport vicinity, and 11 of these were observed more than 150 km away. Dietary preferences based on observations of hunting and feeding owls recorded a total of 192 individuals of 35 species or species types. Educational programs are an important part...

Data on Snowy Owl (Nyctea scandiaca) reproduction on Wrangel Island were collected for six seasons from a total of 423 nests. Nest densities ranged from 0.15 to 0.40 nests/km². Mean clutch size for all 6 years was 6.5 (from 5.3 to 8.4) being significantly higher during low lemming season (7.17) (N = 29) than for peak lemming season (6.0, p < 0.001). Clutch size correlated with weather conditions, females' age, and lemming numbers. Number of young fledged per nest was the highest during peak lemming numbers. Bigamous units occurred only during medium, high, and peak lemming numbers....

In winter 1995/1996, a nearly continent-wide movement of Great Gray Owls (Strix nebulosa) occurred. A sample of 126 owls examined during this period, mainly from northeast of Winnipeg, included a large number from the 1994 hatch-year. If our assumptions regarding molt are correct, 51 birds were from this age class. An inhibited molt condition found in this group suggests a state of inadequate nutrition prior to or during the normal 1995 molt period. We think that a large 1994 hatch and a subsequent food shortage may be factors partly accounting for the 1995/1996 irruption.

Information on wing morphology is important in understanding the mechanics and energetics of flight and in aspects related to reversed sexual size dimorphism in owls. I summarized wing span, wing area, wing loading, root box, and aspect ratio calculations from the available literature and from 113 owls examined in this study. Wing loading estimates for 15 species ranged from 0.211 to 0.545 g/cm². Measurements were available for both male and female owls in 12 species; males of all species had a lower wing loading. In five species with sufficient sample sizes, males had significantly lower...

Red spruce (Picea rubens Sarg.) wood blocks were incubated in modified soil block jars and inoculated with one of nine white rot or brown rot basidiomycetes. Concentrations of calcium, magnesium, potassium, iron, and aluminum were determined using inductively coupled plasma emission spectroscopy in wood incubated 0, 1.5, 4, and 8 months after inoculation. Concentrations of calcium and magnesium tended to increase with time in a linear fashion in wood inoculated with fungi. Patterns of change in potassium concentrations varied. Concentrations of iron and aluminum were high in wood decayed...

The Northern Hawk Owl (Surnia ulula) has never been recorded to breed in Nova Scotia (and only once in recent history in all of the Maritimes). Three pairs of hawk owls were found within 4 km² of woods in 1996, and of these, young were found with two pairs. The first provincial summer record for the Boreal Owl (Aegolius funereus) was also obtained in 1996. These findings increase the known breeding range of hawk owls (and likely that of Boreal Owls) to the south and east of that previously described in North America. The range extension of the hawk owl may be explained by a beneficial...

Mr. Chairman, distinguished guests, owl biologists, ladies and gentlemen. I am very pleased to be with you today to officially open the Second International Symposium on the Biology and Conservation of Owls. I welcome you to Manitoba and bring greetings on behalf of our Premier, Gary Filmon, and the Honorable Glen Cummings, Minister of Natural Resources. As well, a special welcome to the delegates from Europe, Asia, the United States, and delegates from across Canada. We appreciate the effort you have made to come to Winnipeg and I hope your stay in our province and your participation in...