library(ctmm)

setwd(dirname(rstudioapi::getActiveDocumentContext()$path)) 
#> Error: RStudio not running
data("buffalo")
Cilla <- buffalo$Cilla

# accepting the automatic pojection
projection(Cilla)
#> [1] "+proj=tpeqd +lon_1=31.7775407470691 +lat_1=-24.2850983757726 +lon_2=31.8880063438124 +lat_2=-25.024736901024 +datum=WGS84"
m.iid <- ctmm.fit(data = Cilla)
UD0 <- akde(Cilla,m.iid)
ctmm::writeShapefile(UD0,
                     "./shp_without_proj", 
                     file="AKDE_reprex",
                     level.UD=0.95,
                     level=0.95)

# try redefining the projection
Cilla2 <- buffalo$Cilla

# test <- sf::st_crs(42106) # test does not come through with wkt as expected

# proj.4 string for epsg 42106 wg484 lambert azim mozambique
# projx <- sf::st_crs(42106)$proj4string # works if your gdal path includes sf/gdal
projx <- as.character(sp::CRS("+proj=laea +lat_0=5 +lon_0=20 +x_0=0 +y_0=0 +datum=WGS84 +units=m +no_defs"))
projection(Cilla2) <- projx
projection(Cilla2)
#> [1] "+proj=laea +lat_0=5 +lon_0=20 +x_0=0 +y_0=0 +datum=WGS84 +units=m +no_defs"

m.iid2 <- ctmm.fit(data = Cilla2)
UD02 <- akde(Cilla2,m.iid2)
ctmm::writeShapefile(UD02,
                     "./shp_with_new_proj", 
                     file="AKDE_reprex",
                     level.UD=0.95,
                     level=0.95)
sessioninfo::session_info()
#> - Session info ---------------------------------------------------------------
#>  setting  value                       
#>  version  R version 4.0.4 (2021-02-15)
#>  os       Windows 10 x64              
#>  system   x86_64, mingw32             
#>  ui       RTerm                       
#>  language (EN)                        
#>  collate  English_United States.1252  
#>  ctype    English_United States.1252  
#>  tz       America/Los_Angeles         
#>  date     2021-02-25                  
#> 
#> - Packages -------------------------------------------------------------------
#>  package     * version date       lib source        
#>  assertthat    0.2.1   2019-03-21 [1] CRAN (R 4.0.3)
#>  backports     1.2.1   2020-12-09 [1] CRAN (R 4.0.3)
#>  cli           2.3.1   2021-02-23 [1] CRAN (R 4.0.4)
#>  codetools     0.2-18  2020-11-04 [2] CRAN (R 4.0.4)
#>  crayon        1.4.1   2021-02-08 [1] CRAN (R 4.0.3)
#>  ctmm        * 0.6.0   2021-01-10 [1] CRAN (R 4.0.3)
#>  digest        0.6.27  2020-10-24 [1] CRAN (R 4.0.3)
#>  ellipsis      0.3.1   2020-05-15 [1] CRAN (R 4.0.3)
#>  evaluate      0.14    2019-05-28 [1] CRAN (R 4.0.3)
#>  fansi         0.4.2   2021-01-15 [1] CRAN (R 4.0.3)
#>  fs            1.5.0   2020-07-31 [1] CRAN (R 4.0.3)
#>  glue          1.4.2   2020-08-27 [1] CRAN (R 4.0.3)
#>  highr         0.8     2019-03-20 [1] CRAN (R 4.0.3)
#>  htmltools     0.5.1.1 2021-01-22 [1] CRAN (R 4.0.3)
#>  knitr         1.31    2021-01-27 [1] CRAN (R 4.0.3)
#>  lattice       0.20-41 2020-04-02 [2] CRAN (R 4.0.4)
#>  lifecycle     1.0.0   2021-02-15 [1] CRAN (R 4.0.4)
#>  magrittr      2.0.1   2020-11-17 [1] CRAN (R 4.0.3)
#>  pillar        1.5.0   2021-02-22 [1] CRAN (R 4.0.4)
#>  pkgconfig     2.0.3   2019-09-22 [1] CRAN (R 4.0.3)
#>  purrr         0.3.4   2020-04-17 [1] CRAN (R 4.0.3)
#>  raster        3.4-5   2020-11-14 [1] CRAN (R 4.0.3)
#>  Rcpp          1.0.6   2021-01-15 [1] CRAN (R 4.0.3)
#>  reprex        1.0.0   2021-01-27 [1] CRAN (R 4.0.3)
#>  rgdal         1.5-23  2021-02-03 [1] CRAN (R 4.0.3)
#>  rgeos         0.5-5   2020-09-07 [1] CRAN (R 4.0.3)
#>  rlang         0.4.10  2020-12-30 [1] CRAN (R 4.0.3)
#>  rmarkdown     2.7     2021-02-19 [1] CRAN (R 4.0.4)
#>  rstudioapi    0.13    2020-11-12 [1] CRAN (R 4.0.3)
#>  sessioninfo   1.1.1   2018-11-05 [1] CRAN (R 4.0.3)
#>  sp            1.4-5   2021-01-10 [1] CRAN (R 4.0.3)
#>  stringi       1.5.3   2020-09-09 [1] CRAN (R 4.0.3)
#>  stringr       1.4.0   2019-02-10 [1] CRAN (R 4.0.3)
#>  styler        1.3.2   2020-02-23 [1] CRAN (R 4.0.3)
#>  tibble        3.0.6   2021-01-29 [1] CRAN (R 4.0.3)
#>  utf8          1.1.4   2018-05-24 [1] CRAN (R 4.0.3)
#>  vctrs         0.3.6   2020-12-17 [1] CRAN (R 4.0.3)
#>  withr         2.4.1   2021-01-26 [1] CRAN (R 4.0.3)
#>  xfun          0.21    2021-02-10 [1] CRAN (R 4.0.3)
#>  yaml          2.2.1   2020-02-01 [1] CRAN (R 4.0.3)
#> 
#> [1] C:/Users/gcotterill/Documents/R/win-library/4.0
#> [2] C:/Program Files/R/R-4.0.4/library