Recent advances in radio-transmitter technology have produced sub-gram transmitters which allow small birds to be radio-tracked so that researchers can ascertain information on species movement and behavior to inform conservation and management plans. However, the ability to study some species remains limited by practical problems with transmitter attachment. As a result, improvements in design may be hindered by underreporting of retention rates and attachment issues. We monitored retention rates for glue-attached radio-transmitters on two bird species in southern Ontario with different life histories. Mean retention time for Chimney Swifts (Chaetura pelagica) was ≥25.1 days (± 12.8 SD, n  =  12, May–Aug 2010 and 2011), while for Bobolinks (Dolichonyx oryzivorus) we estimated mean retention time at under 24 hrs (n  =  15, May–Jul 2011). We discuss potential reasons for this disparity and suggest improvements to transmitters and attachment methods for short-term use on small birds where tag retention and damage may be problematic, as Bobolinks were capable of removing transmitters and breaking antennas which, in some cases, rendered the devices inoperative. We collated retention estimates from published studies that marked birds with glue-attached radio-transmitters; these studies used a wide range of methods with varying success on different species, however, few studies specifically examined the effects of alterations in glue attachment methods on retention. We encourage researchers to report retention rates to improve the use of resources in other studies and enable advancements that will augment the potential of existing radiotelemetry technology.