This part of the Home Page allows you to select a species,
a region, and a starting and ending year, and conduct an analysis of population change for
that species, region, and period.
We identify a few limitations of trend data in our
credibility measures discussion. Also note the
disclaimer associated with all results.
Regional summary results presented here are based on peer-reviewed analyses of
BBS data. Spreadsheets containing trend and annual index results of these
analyses for all species and regions over long term (1966-2024 for core species
and core areas) and recent (1993-2024 for core and non-core species in core and
expanded areas) intervals are published on the USGS Sciencebase archive, at:
Results are based on a set of hierarchical models for population change, as
described in Link and Sauer 2020. Depending on the
species, we use one of four hierarchical models to estimate annual indices of
abundance and trend for a region. The Markov chain Monte-Carlo method used to
fit the model is an interative fitting procedure, which produces a series of
replicates from which the estimates and their credible intervals can be
derived. This summary program uses these replicates, summarized at the level
of stratum within states or Provinces, aggregates them into regional estimates
for the selected region, and calculates a trend as a ratio of annual indices
corresponding to the first and last years of the selected interval.
Starting in 2017, BBS results have been presented for a "Core" survey area
(strata in which at least some routes have data extending from 1968 to
present), and for an "Expanded" survey area that contains the Core strata as
well as several non-Core strata in Alaska and northern Canada that were not
consistently surveyed prior to 1993. Of the 548 species for which we estimate
trends, 426 of them occur in the Core Region (Core Species), and for
those species we present trends both for core strata and for Expanded area
strata. For Core Species, results for both 1966-2024 and
1993-2024 are presented for Core portions of US, Canada, and Survey-wide for
these species. Regions that are labeled as "Expanded" are based on all strata
(Core and non-Core) and results for those regions are only computed for
1993-2024. The remaining 122 species (i.e., Non-core Species) only
(or primarily) occur in the Expanded survey area, and for these species we
only present results for expanded regions over the interval 1993-2024. Full
details of these regions and species are available in
Sauer et al 2017.
Output from the program includes:
Trend estimates for the selected interval;
95% Credible Intervals for the trend estimate;
Long-term estimates of trends with credible intervals for the selected species and region; and
Annual indices and credible intervals from the first year of the survey to the current year of analysis for the selected species and region.
User Notes:
This analysis is quite new, and we welcome comments regarding the analysis and results.
Input
Select the species:(start typing to search...)
Select the region of interest:
First year:
Last year:
Credible Intervals:
90%
85%
80%
Results
Data Liability Disclaimer
Although these data have been processed successfully on a
computer system at the United States Geological Survey (USGS), no warranty
expressed or implied is made regarding the accuracy or utility of
the data on any other system or for general or scientific purposes,
nor shall the act of distribution constitute any such warranty.
This disclaimer applies both to individual use of the data and
aggregate use with other data. It is strongly recommended that
these data are directly acquired from a USGS
server, and not indirectly through other sources which may have
changed the data in some way. It is also strongly recommended that
careful attention be paid to the contents of the metadata file
associated with these data. The USGS shall
not be held liable for improper or incorrect use of the data
described and/or contained herein.
These data are provided "as is" and without any express or implied warranties,
including, without limitation, the implied warranties of merchantability and
fitness for a particular purpose.
Also, use of trade names or commercial products in this home page is solely for
the purpose of providing specific information, and does not imply recommendation
or endorsement by the U.S. Government.