<Grid x:Name="xx" RenderTransformOrigin="0.5,0.5">
<Grid.RenderTransform>
<TransformGroup>
<TranslateTransform />
<RotateTransform />
</TransformGroup>
</Grid.RenderTransform>
...................
<VisualStateGroup x:Name="Beak">
<VisualState x:Name="OpenBeak">
<Storyboard RepeatBehavior="Forever">
<DoubleAnimationUsingKeyFrames Storyboard.TargetName="xx" Storyboard.TargetProperty="RenderTransform.Children[0].X">
<SplineDoubleKeyFrame KeyTime="0" Value="0" />
<SplineDoubleKeyFrame KeyTime="0:0:0.3" Value="0" />
<SplineDoubleKeyFrame KeyTime="0:0:0.4" Value="-4.037" />
</DoubleAnimationUsingKeyFrames>
<DoubleAnimationUsingKeyFrames Storyboard.TargetName="xx" Storyboard.TargetProperty="RenderTransform.Children[1].Angle">
...................