Scientists have long known that birds are feeling the heat due to climate change. However, a new study of a dozen affected species in the Western Cape suggests their decline is more complex than previously thought — and in some cases more serious.According to the study, published in Conservation Physiology, by scientists from the Percy Fitzpatrick Institute at the University of Cape Town and Nelson Mandela Metropolitan University, there could be several reasons why birds are being negatively affected by human-made climate change.