Population change in the small Canadian population of Henslow's Sparrow is difficult to quantify. The species is not detected in sufficient numbers in Canada by the Breeding Bird Survey (BBS), or other large-scale monitoring programs, to provide robust trends estimates. However, breeding bird atlases in Ontario and Quebec provide good coverage of the species' range and its occurrence. Henslow's Sparrow was found in 38 atlas squares in the first Ontario atlas (1981-1985) but only 9 in the second (2001-2005; Tuininga, 2007). Despite extensive efforts to visit historic sites, far fewer birds were detected and at fewer sites. Although the probability of observation from the Atlas data does not equate directly to abundance, and despite these data now being somewhat out of date, a change of this magnitude provides good evidence of a significant decrease in numbers during that time. More current information will be available after the third Ontario atlas is completed in 2025. Henslow's Sparrow has always been extremely rare in Quebec; there were 5 males recorded in the first Quebec atlas (Bannon, 1996) and none in the second atlas (Atlas of the Breeding Birds of Quebec, 2017). In the past ten years, there have only been scattered sightings reported in Canada on eBird (eBird, 2018). The declines observed in the Canadian population are consistent with the trend seen in the North American population, which the BBS shows has declined by 60% since 1970.

The goal for Henslow's Sparrow is to establish a stable breeding population of at least 5-10 pairs. This goal is defined in the Recovery Plan for Henslow's Sparrow under the Species at Risk Act (Environment Canada, 2010). Although monitoring is poor, the national population of Henslow's Sparrow is likely below its goal range.