We've had really good birding at Thickson's Woods this spring. On last weekend's OFO outing we ran into quite a few species of warbler (highlighted by a lovely N. Parula singing his heart out) a Great Crested Flycatcher and Blue Headed Vireos.
We also love birding Tommy Thompson Park. The range of habitat available on a single hike makes birding The Spit a ton of fun, with opportunities for very high #s of species. We'd typically have to drive to multiple locations in Durham to catch the same habitat variation available in a round the park walk of TTP.
Given where we are in migration, I'd say that you can't go wrong with either.
If your'e coming out to Durham, do yourself a favour and plan some more time for a pop in to Oshawa Second Marsh and a look in to the Cranberry Marsh while you're at it.
Happy Birding,
Pat