Female wolves give birth only in the spring when food is plentiful and water is in the liquid form (not ice or snow). They can also rely on the pack to provide for the pups.
Contrast that with free-roaming dogs. Females, through our work of domestication, have lost the ability to conceive only once a year in the spring. In our northern climates, they give birth in the snow at sub-zero temperatures when all is frozen around them, including drinking water.
More than ever, a lactating bitch needs water for her own maintenance and milk production. She will need to eat roughly 10 cups of snow to convert it into 1 cup of water while staying warm in the process. As for finding unfrozen food…
This is reason #2 why targeting females first and foremost in managing a population of unwanted dogs is the right thing to do. If you are not targeting females, why not?
If you are still unconvinced, there is reason #3 coming next.
Dr. Judith Samson-French