[LTER-hbr-im] questions re Hubbard Brook bird population changes (website raw data vs. trends described in your new HB book)

[Nora Hanke]

Hello

I am a graduate student in Environmental Studies at Antioch University and
have been enjoying your' wonderful *Hubbard Brook* book. I am researching
some aspects of the HB studies and don't understand what appear to be data
discrepancies.

Specifically, I am confused by looking at the raw data published on the HB
website in comparison to the species trends documented in *Hubbard Brook*
(2016). (I know the latter are for a period ending in 2013.)
For example, Hairy Woodpeckers are described as fairly stable, but
comparing their numbers in the first 4 years of the study with the period
2012 through 2015, they appear to have doubled. Swainson's Thrushes are
described as stable, but the average of their no.s in recent years are
under a quarter of their abundance in an average of the study's first few
years. Philadelphia Vireos are described as declining (rather than
disappeared), but they have not been noted in the HB study site since 1982,
according to the website's data. Similarly, Veeries are described as
declining, but were last counted in 2005.
I am guessing that the HAWO and SWTH number changes are not statistically
significant, or else your threshold for defining population change is
greater than the population changes noted in the two comparison periods I
am studying. But I really don't get the interpretation for the birds that
are gone - according to the HB website published abundance data.
I apologise if I am obtuse or show a horrific lack of understanding
biostatistics or interpreting raw data. I will be studying biostatistics
next semester. In the meantime, I am currently writing a paper on your bird
studies and deeply mystified.
I would appreciate some clarification, if you have time to respond.
Thank you!

Nora E Hanke
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