The boom years most capture the fascination of us butterfly counters. 2001 was all that for Red Admirals (see the summer 2002 column, also on NABA's website: www.naba.org). Bust years, like 1996 for the Red Admiral (see the fall 2002 column) are also remarkable-if you notice them, and it can be harder to spot an absence than an overwhelming presence.

     But what's so important about all the other years? For example, 1998 was fairly typical for Red Admirals.

     This map shows their relative abundance on 1998 counts, held from January 3 to November 30, as individuals per party-hour per count. (Party-hours = total hours of observation summed for all parties, or groups, of counters on a count.) These "observation rates" of butterflies per hour of counting make it possible to compare relative abundance among counts. For example, two counts might report 50 Red Admirals. But if one count had 5 party-hours and the other had 50 party-hours, then Red Admirals were relatively more abundant in the places counted in the first count circle (10 per party-hour) than in the second (1 per party-hour).

     In 1998, the percentage of counts north of Mexico recording the Red Admiral (60.7%) falls right at the long-term average-for 1982-2001, the mean percentage of counts recording any Red Admirals was 59.7% per year, and the median was 61.0%.

     The geographic range of Red Admirals in 1998 counts was also average. In 2001, Red Admirals extended as far north as Canadian counts occurred. In 1996, Red Admirals barely reached into Canada in two of the five provinces with counts. In 1998, Red Admirals also occurred on counts in only two provinces, but reached further north and in relatively higher abundances.

     The experience on a given count could be quite different from prevailing continental patterns, because of habitat, timing of count date relative to timing of the Red Admiral life cycle, and local variation in butterfly abundance. The only way to know what is a boom, or a bust, or typical for your area is to keep counting "your butterflies" year after year!

Copyright © 2002 by the North American Butterfly Association, Inc. All rights reserved.