Building on Ryan’s 2020 PNAS paper about the timing of ‘cold snaps’ relative to breeding for tree swallows. He showed that in our Ithaca TRES population:
Idea for this paper is to essentially repeat that study but with many sites/years/species and to explicitly compare breeding performance for aerial insectivores (swallows, martins, flycatchers) to non aerial-insectivores (blubirds, chickadees, nuthatches, titmice, etc) that should not be as impacted by short cold snaps.
Predictions are the same as in the PNAS paper with the additions that:
rnoaapackage and choose stations that:
For each species, calculate change in breeding phenology over time? For TRES we had records back to the 60/70s, but most of these only start in mid 90s so not sure how much we can detect here.
For each breeding record, calculate relative reproductive success. Will need to account for lat/long variation in average clutch/fledge size somehow. Also need to standardize across all species so that RS is a z-score of RS relative to species mean and relative to the expected RS for that particular location. This is actually going to be tricky because of course to the extent that temperature changes the clutch size pattern with latitude it might change some over the 25 years of data.
For each breeding attempt, calculate the offset in days from hatching to the last cold snap of the year using above criteria. Could get into more weather data specifically experienced for each nest but maybe that is best to skip at first.
Ask does date of last cold snap predict fledging RS (or fledge yes/no) and does the pattern differ for aerial insectivores vs. non aerial insectivores. Maybe need to also run this as phylogenetic correction for relationships?
I made a hexagonal grid with 3 degree width hexagons. Because these are equal degree size, the actual land area varies a bit as you go north. I don’t think that is a problem since the total area doesn’t really factor into any analyses. I also plotted 1 or 2 degree grids, but those seem too small to work with in terms of having decent numbers of breeding records, etc. Of course the grid size is somewhat arbitrary here.