Bar Chart Histograms

In constructing these histograms, the year is broken up into 36 time periods, 1/3 month in duration. The quantity plotted is "Fraction of time observed", which is obtained by dividing the number of times that I observed a given species during a given time period by the number of times that I visited the park during that time period. Data has been recorded more or less continuously since Jan. 1992, and the data for all years has been combined for the histograms. The data must be treated with some caution, since most of my visits have been around lunch time (not the peak time for observing woodland birds, especially in summer). Also, my visits have ranged in duration from 15 min to 1.5 hrs, and the data has not been normalized to reflect this. However, by combining data from many years, I think the histograms represent some real and interesting trends in the occurence of bird at Institute Park.

Links to the histograms are provided in the annotated checklist. You can also browse the histograms directly from the following menu:

• Herons, Grebes, Cormorants
• Dabbling Ducks
• Wigeon plus Diving Ducks
• Hawks and other raptors
• Shorebirds and Coots
• Gulls
• Doves, Swifts, Kingfisher, Woodpeckers
• Flycatchers and Swallows
• Jays, Chickadee, Nuthatchs, Creeper
• Kinglets, Robin, Catbird, Mockingbird, Waxwing
• Vireo's, Warblers
• More Warblers
• Still more Warblers
• Cardinal and Sparrows
• Blackbirds and Finchs