\documentclass[12pt,a4paper]{report}
\usepackage{graphicx}
\usepackage{caption}
\usepackage{subcaption}

\begin{document}

\begin{figure}[!ht]
\begin{subfigure}[b]{0.3\textwidth}
\centering
\includegraphics[width=.85\linewidth]{example-image-a}
\caption{A gull}
\label{fig:gull}
\end{subfigure}%

\begin{subfigure}[b]{0.3\textwidth}
\centering
 \includegraphics[width=.85\linewidth]{example-image-a}
\caption{A gull2}
\label{fig:gull2}
\end{subfigure}%
\begin{subfigure}[b]{0.3\textwidth}
\centering
 \includegraphics[width=.85\linewidth]{example-image-a}
 \caption{A tiger}
\label{fig:tiger}
\end{subfigure}%
 \caption{Pictures of animals}\label{fig:animals}
\end{figure}

\end{document}