Drought and Monarch Migration in Texas Contributed by Dr. Bill Calvert Because of very scant rainfall since June, a pathetic situation was evident over much of Central Texas prior to yesterday. The Hill Country (Edwards Plateau) was reduced to conditions that must be like the Kalahari Desert. Creeks that normally flowed year around became sporadic water holes, each of which seemed to have a sentinel heron guarding it and looking hungrily down into the school of congregated fish, trapped there by the vanishing waters. These few watering spots, fed by the remains of springs, served to attract all kinds of wildlife. The only viable nectar sources were there. Coons, possums and ring tailed cats congregated there at night and white tailed deer and feral pigs could be flushed almost anytime. No evidence of big cats, but they too must be waiting for their chance at some of the bigger game. One of the plants most severely affected by the drought is frostweed (Verbisina virginica). In past years, this species has served as a major nectar source for migrating monarchs. It's blooming always seemed to coincide with the passage of migrant monarchs and monarchs always seemed to gain weight during their passage through the region. Frostweed, a composite, grows in dense patches under the periphery of oak motts and other species of trees. By fall it is usually at least three feet high and has dense clusters of snow white flowers upon which nectaring monarchs can often be found. In areas that had experienced little of no rainfall all summer, these plants were reduced to short remnants with sad-looking, droopy leaves and no blooms. In some areas where summer thunderstorms had provided some moisture the situation was not so dire. Here frostweed had grown to its normal stature and was in full flower. One such place was along the Medina River near Bandera, Texas. Hundreds of fresh looking monarchs were nectaring on frostweed there Sunday afternoon September 24th. But all this changed abruptly yesterday evening when a whopping strong "norther" smashed through bringing rain to much of the Hill Country. Rainfall estimates were 2-4 inches west of San Antonio, a spot that had felt the drought most severely. It remains to be seen whether the frostweed and other nectar sources can recover in time to be of help to the migrating monarchs which have already reached Abilene, and may have reached the Medina River valley. It would be most interesting to get weights of monarchs as they progress towards Mexico. Comparison of weight from location to location (Minnesota vs Kansas vs Texas for example), and from year to year would tell us much about the use of available nectar by the migrants and the effect of drought on their health. We hope to collect some of this data (weights, sizes and conditions) in the weeks ahead. We would be most happy to share it with those of you who have collected similar data in other locations! The University of Minnesota website, Monarch Lab will show you how to weigh, determine sex, measure size and assess condition of migrant butterflies. Contributed by Dr. Bill Calvert Texas Monarch Watch (wcalvert@flash.net) Copyright 2000 Journey North. All Rights Reserved. Please send all questions, comments, and suggestions to our feedback form