The wildlife situation in Chernobyl is complex.
Here are some BBC reports. The BBC sometimes mangles science reporting. I'd be interested to read more modern articles.
http://news.bbc.co.uk/1/hi/6946210.stm
> Recent studies said rare species had thrived despite raised radiation levels as a result of no human activity.
> But scientists who assessed the 1986 disaster's impact on birds said the ecological effects were "considerably greater than previously assumed".
http://www.bbc.co.uk/nature/14250489
> "But what we're finding is that there is a significant impact on both the population and the biodiversity - the number of species - in the zone. And it's directly proportional to the level of contamination."
> But this is one side of a polarised scientific debate.
http://news.bbc.co.uk/earth/hi/earth_news/newsid_9387000/938...
> Birds living around the site of the Chernobyl nuclear accident have 5% smaller brains, an effect directly linked to lingering background radiation.
http://news.bbc.co.uk/1/hi/sci/tech/7949314.stm
> According to researchers working in the exclusion zone surrounding Chernobyl, there is a "strong signal of decline [of insects] associated with the contamination".
> The team found that bumblebees, butterflies, grasshoppers, dragonflies and spiders were affected.