Year in review (2022)

Species richness over time at the five montane sites.  Overall, 2021 was a mixed bag... mini rebounds at Donner Pass, Castle Peak and Sierra Valley; in contrast: exceptionally poor years at Lang Crossing and Washington.

(thanks to Chris Halsch for this and all graphs on this page)

Standardized population index over time, representing average (among species) performance.  This metric is calculated by taking the number of days a butterfly was seen, dividing by the number of visits to that site each year (i.e., what we have called "fractional day positives" in publications), and then scaling within that unique species/site combination.  A value of 0 indicates an average year.  This metric is restricted to species that have been seen at a site at least 10 years.  Most butterflies at most sites contined on the historical downward trend, with the notable exception of Donner Pass where many species appear to be having a pretty good time of the last couple of years.

The date of the survey that saw the most species each year. Many sites reached their peak later in the year (relative to the historical average).

The standardized date of first flight across species.  This metric is calculated by determining the date a butterfly was first observed in a year and then standardizing that date within that species across years.  A value of 0 represents the average date of first flight, low values are earlier in the year, and larger values are later in the year.  Quite an average year for first flight dates!

Number of monitoring surveys per year.  The sample effort for 2022 was comparable to historic sampling effort.  For quirks of weather and scheduling, Donner was visited slightly less (both this year and the last two years) relative to the long-run average.

Species that had pronounced deviations from their historic average day positive rate in 2022 relative to the entire time series.  Among the 50 strongest deviations from baseline, the majority were negative (i.e., species that had an exceptionally bad year in 2022).  Check out buckeyes (Junonia coenia) having a great 2022!