Error(s) in re-building vignettes:
--- re-building 'BIRDS.Rmd' using rmarkdown
Quitting from lines 75-105 (BIRDS.Rmd) 
Error: processing vignette 'BIRDS.Rmd' failed with diagnostics:
identicalCRS(x, y) is not TRUE
--- failed re-building 'BIRDS.Rmd'

--- re-building 'technical_details.Rmd' using rmarkdown
--- finished re-building 'technical_details.Rmd'

--- re-building 'working_with_xts_timeseries.Rmd' using rmarkdown
Loading required package: zoo

Attaching package: 'zoo'

The following objects are masked from 'package:base':

    as.Date, as.Date.numeric

Warning in showSRID(uprojargs, format = "PROJ", multiline = "NO", prefer_proj = prefer_proj) :
  Discarded ellps WGS 84 in CRS definition: +proj=merc +a=6378137 +b=6378137 +lat_ts=0 +lon_0=0 +x_0=0 +y_0=0 +k=1 +units=m +nadgrids=@null +wktext +no_defs
Warning in showSRID(uprojargs, format = "PROJ", multiline = "NO", prefer_proj = prefer_proj) :
  Discarded datum WGS_1984 in CRS definition
Warning in spTransform(polygon, CRSobj = CRS("+init=epsg:3857")) :
  NULL source CRS comment, falling back to PROJ string
Warning in spTransform(polygon, CRSobj = CRS("+init=epsg:3857")) :
  +init dropped in PROJ string
Warning in wkt(obj) : CRS object has no comment
Warning in proj4string(obj) :
  CRS object has comment, which is lost in output
Warning in proj4string(x) :
  CRS object has comment, which is lost in output
Warning in showSRID(uprojargs, format = "PROJ", multiline = "NO", prefer_proj = prefer_proj) :
  Discarded datum WGS_1984 in CRS definition,
 but +towgs84= values preserved
Warning in showSRID(uprojargs, format = "PROJ", multiline = "NO", prefer_proj = prefer_proj) :
  Discarded datum Unknown based on WGS84 ellipsoid in CRS definition
Quitting from lines 26-43 (working_with_xts_timeseries.Rmd) 
Error: processing vignette 'working_with_xts_timeseries.Rmd' failed with diagnostics:
identicalCRS(x, y) is not TRUE
--- failed re-building 'working_with_xts_timeseries.Rmd'

SUMMARY: processing the following files failed:
  'BIRDS.Rmd' 'working_with_xts_timeseries.Rmd'

Error: Vignette re-building failed.
Execution halted