There are three types of deer in the country - red, sika and roe.
Their numbers are increasing, with the red deer population getting three times bigger.
The report says the deer are becoming pests.
They're eating too much, ruining crops and woodlands.
They're also wandering on to the roads, causing accidents.
Culling
The report - by conservation groups the WWF and the Royal Society For The Protection Of Birds - has led to calls to control the deer population.
This could include culling, which involves killing some of them off.
But not everyone agrees that culling is the answer.
So, there will be no changes until more research is carried out.
Hear story 
Watch story
Play Poacher Patrol
Click here to talk about animals
Deer quiz
