Presentation on theme: "Earlier Spring Arrival Dates of Migrating Birds Verified in New York and Massachusetts Christopher Klee and Steven Houck Le Moyne College Donald McCrimmon,"— Presentation transcript:
Earlier Spring Arrival Dates of Migrating Birds Verified in New York and Massachusetts Christopher Klee and Steven Houck Le Moyne College Donald McCrimmon, Faculty Mentor
Bird Migration Phenology Phenology is a branch of science dealing with the relations between climate and periodic biological phenomena. Such as bird migration or plant flowering. Many species of birds leave the northeastern states to winter in places where food is abundant. They return in the spring, when food again becomes available to feed their young. If the environment has grown warmer over the decades, we might expect birds to migrate northward sooner and arrive earlier.
What is the Evidence for Changes in Temperature? The average temperature from January to May in the northeastern US has increased significantly over the past century. These data are from Ithaca Soot and sulfate aerosols are thought to have reversed the rate of increase from 1940-70, but overall it’s still statistically significant. Mathematically, (by finding the second derivative) we can see that the point where temperature really increases is in the year 1950.
Methods Our hypothesis is that First Arrival Dates (FADs) are progressively earlier as temperature increased in the 20 th and early 21 st Centuries We obtained FADs from Worcester, MA and the Cayuga Lake Basin, NY from Dr. Chris Butler (Ibis 2003). These were records from 1932-1993 published in the Forbush Bird Club journal, The Chickadee. Cayuga Bird Club records were also digitized by Butler from records extending back to 1903. We then added data from 1994-2013 for both clubs, correcting some previous transcription errors in the Forbush data set.
Methods Statistical Analysis: We converted calendar FADs (month, day) to Julian dates (number in a year of a day and month, e.g. January 1 = 1, December 31 = 365 or 366 in leap years) We compared average FADs for 28 bird species that Butler (Ibis 2003) had found to demonstrate earlier arrival dates over multiple decades in both MA and NY. Over time Intervals: 1903-1950, 1951-1993, 1994-2013 – following Butler’s original analyses By Migration Distance Short vs Long
All images from Birds of North America galleries
Results – Bonferroni Tests Among Interval Means Cayuga - IntervalSignificanceForbush - IntervalSignificance 03-50 vs 51-93.04803-50 vs 51-93.134 03-50 vs 94-13.00103-50 vs 94-13.006 51-93 vs 94-13.51751-93 vs 94-13.765
Discussion Our results are generally consistent with Butler’s Increasingly earlier arrivals in both regions. Particularly pronounced between the earliest and most recent intervals Butler determined the short distance migrants arrived earlier than long distance migrants Our analysis showed that differences in arrival dates between these groups were not statistically significant. This result bears additional follow up Long distance migrants over wintering in Central and South America should be less influenced by weather conditions in the north-east US, with no way of directly knowing weather conditions on breeding grounds. Some species show evidence of over-wintering (i.e., not migrating). For example, Yellow-rumped Warbler and Fox Sparrow These partial results are preliminary. 28 of 103 species.
Acknowledgments The Members of the Cayuga and Forbush Bird Clubs 1903 - 2014 Dr. Chris Butler Dr. Charles Smith Dr. Lawrence Tanner Fr. George Coyne Ms. Katheryn Hennigan Dr. Richard Quimby Dr. Caitlin Cunningham Mr. John Livermore