A good starting point for ornithological research are the journals produced by the Ornithological Council’s societies:

Society Name	Journal Name	Open access?
Association of Field Ornithologists	The Journal of Field Ornithology	Yes
BirdsCaribbean	Journal of Caribbean Ornithology	Yes
CIPAMEX	Huitzil Revista Mexicana de Ornitología	Yes
Neotropical Ornithological Society	Ornitología Neotropical	Yes
North American Crane Working Group	Proceedings for North American Crane Workshops	Yes
Pacific Seabird Group	Marine Ornithology	Yes
Raptor Research Foundation	Journal of Raptor Research	No
Waterbird Society	Waterbirds	No
Wilson Ornithological Society	The Wilson Journal of Ornithology	No

You can also find a more in-depth database of ornithological journals at the Ornithological Exchange, an online community manages by the Ornithological Council.