\ProvidesAnimalsLang{en-US}

\RequireAnimalsLang{english}%

\providecommand*{\englishUSanimals}{%
  \englishanimals
  \renewcommand*{\ladybirdname}{ladybug}%
}

\englishUSanimals

\@ifundefined{captions\CurrentTrackedDialect}%
{%
  \@ifundefined{captions\CurrentTrackedLanguage}{}%
  {%
    \expandafter\g@addto@macro
      \csname captions\CurrentTrackedLanguage\endcsname{\englishUSanimals}%
  }
}%
{%
  \expandafter\g@addto@macro
    \csname captions\CurrentTrackedDialect\endcsname{\englishUSanimals}%
}