There are lots of arguments for and against black and white images. My choice of black and white is simple, pragmatic and thoroughly unromantic. I choose black and white when colour won't work and mono has the elements it needs.
Each time we visit a major city for any time, the zoo tends to be on the short list. Often the images are a matter of making the best of what you get with mixed light and limited time. After a particularly unsatisfying trip to Melbourne zoo (poor light and time constraints), I struggled with the resulting images and in desperation converted them to mono. It allowed me to salvage some pretty poor files to an acceptable standard. As time went on the black and white zoo series became a thing. Visits became about the images with mono in mind from the outset. Sometimes an image is as good or better in colour, and this leaves me with a dilemma, continue the series or deviate. So far mono has held sway.
The pelican image was captured 10 minutes into a trip to Perth zoo last year. it is not super sharp due to poor light and subject movement and the colour image is cool and flat, but mono allowed the textures, clean lines and personality of the bird to come out. Black and white images have fewer underpinning elements than colour images. They need tone and texture, subject and compositional strength.
The image was taken with an EM5 and 75-300 lens at 300mm, wide open. the shutter speed was about 1/250, ISO 400. In hindsight a higher ISO would have allowed either a faster shutter speed and/or more depth of field. Removing unwanted clutter from the background also strengthened the image.