Poaching is the illegal taking of resources that includes but is not limited to, animals, plants, and even minnerals. Taking these resources from the wild causes a decline in resources, habitat, and species diversity. Animals like the white rhino that are poached for psuedo-medical  purposes are endangered in the wild because their horn is in high demmand. 

This is a white rhino, one of the most endangered animals on earth due to poaching.
Even animals as small as this sea horse are threatened by poaching.
Other animals are poached for their believed 'medicinal healing qualities.' Most of which is pseudo-science.
Animals aren't only poached for their hides and tusks. The poaching of animals like small primates and orangutans attracts a lot of activity from the illegal pet trade.
This 19th century Tiffany and Co. vase shows the emphasis placed on exotic items. Items like these put the demand for ivory at an all time high, closely correlating with a rise in illegal activities
The hides of hundreds of leopards lie in a pile. Items like these that fetch high prices have led to a sharp decline in wild stock.
Credits: All media
This user gallery has been created by an independent third party and may not always represent the views of the institutions, listed below, who have supplied the content.