Error(s) in re-building vignettes:
--- re-building ‘a01_GettingStarted.Rmd’ using rmarkdown
Warning in engine$weave(file, quiet = quiet, encoding = enc) :
  Pandoc (>= 1.12.3) not available. Falling back to R Markdown v1.
Quitting from lines 40-78 (a01_GettingStarted.Rmd) 
Error: processing vignette 'a01_GettingStarted.Rmd' failed with diagnostics:
invalid 'path' argument
--- failed re-building ‘a01_GettingStarted.Rmd’

--- re-building ‘a02_VitalRates.Rmd’ using rmarkdown
Warning in engine$weave(file, quiet = quiet, encoding = enc) :
  Pandoc (>= 1.12.3) not available. Falling back to R Markdown v1.
--- finished re-building ‘a02_VitalRates.Rmd’

--- re-building ‘a03_LifeHistoryTraits.Rmd’ using rmarkdown
Warning in engine$weave(file, quiet = quiet, encoding = enc) :
  Pandoc (>= 1.12.3) not available. Falling back to R Markdown v1.
--- finished re-building ‘a03_LifeHistoryTraits.Rmd’

--- re-building ‘a04_AgeFromStage.Rmd’ using rmarkdown
Warning in engine$weave(file, quiet = quiet, encoding = enc) :
  Pandoc (>= 1.12.3) not available. Falling back to R Markdown v1.
--- finished re-building ‘a04_AgeFromStage.Rmd’

--- re-building ‘a05_TernaryPlots.Rmd’ using rmarkdown
Warning in engine$weave(file, quiet = quiet, encoding = enc) :
  Pandoc (>= 1.12.3) not available. Falling back to R Markdown v1.
Welcome to popdemo! This is version 1.3-0
Use ?popdemo for an intro, or browseVignettes('popdemo') for vignettes
Citation for popdemo is here: doi.org/10.1111/j.2041-210X.2012.00222.x
Development and legacy versions are here: github.com/iainmstott/popdemo
Loading required package: ggplot2
--
Remember to cite, run citation(package = 'ggtern') for further info.
--

Attaching package: 'ggtern'

The following objects are masked from 'package:ggplot2':

    aes, annotate, ggplot, ggplotGrob, ggplot_build, ggplot_gtable,
    ggsave, layer_data, theme_bw, theme_classic, theme_dark,
    theme_gray, theme_light, theme_linedraw, theme_minimal, theme_void

--- finished re-building ‘a05_TernaryPlots.Rmd’

SUMMARY: processing the following file failed:
  ‘a01_GettingStarted.Rmd’

Error: Vignette re-building failed.
Execution halted