Changes in First and Last Recorded Activity Dates Over Time

This chart presents a time-series summary of recorded observations. It is based on available records at the time of analysis and will evolve as further data are added. The five-year moving average provides a smoothed representation of variation in recorded adult and immature activity over time, helping to illustrate longer-term trends in the earliest and latest recorded dates.

Individual observations are shown as ● circles (earliest dates) and ▲ triangles (latest dates). These markers represent actual recorded values for each year. Where a marker lies noticeably above or below the corresponding moving-average line, it indicates that the recorded date differs from the smoothed trend suggested by the surrounding years. Such values remain part of the underlying data used to calculate the five-year moving average, but their individual positions are preserved on the chart, allowing departures from the broader trend to be identified.

Annual record totals are shown for context; years with fewer records may provide a less complete representation of activity than years with higher recording intensity. Interpretation should consider that apparent trends may reflect both biological change and variation in recording effort.

Note: Clicking either the Adult Range.... or Immature Range... legends allows you to hide them, to show more discrete data.