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.