It's not odd. Sterilization without any additional measures is useless. People will keep buying and abandoning dogs. And if there's enough food, they will reproduce faster than you can catch and sterilize them
Since they have been doing it for 15 years, they now presumably have structures and processes in place to keep up with sterilizing more dogs. They also had lots of volunteers helping. If this keeps going, it's probably manageable in the future.
The only sane, permanent solution is to police (prospective) animal owners or traders, who are the actual root cause of such mess. Why should everybody else compensate indefinitely for their lack of care and character?
If it's a step down from 100k, it's progress! Also, the numbers have been decreasing for a long time already, else Bhutan couldn't conclude that they are done.
I agree. Their numbers are either so low that it counts as "done", or they actually didn't encounter any for a certain amount of time. They must either continuously sterilize the small trickle of remaining strays or plan a follow-up campaign. Implementing low-cost tree registration of pets should also help.
I imagine sterilising the ones you've caught is the easy part. How do you actually catch them all though?
They claim to have sterilised 150000 dogs. At the beginning of the programme, you could reasonably assume that every stray dog you see needs to be processed. Later on in the programme, you'll be releasing a lot of dogs that have already been processed, which seems like a lot more effort for the last 10% compared to the first 10%.
In these programs it is standard to mark the animal in some way. In NYC, for instance, you clip the top of one ear of a cat after it's been processed.
So you catch ten animals, immediately let go any ones that have been marked, process the last one or two -- still more effort to catch, but less effort to treat.
They could just not bother to catch them if they see ones with clipped ears. Also, catching them might be quite simple if you attract them with treats and treat them decently.
Fertility control alone: 12% to 40% population decrease. More effective over longer time spans (up to 20 years)
Culling alone: Effective in rapidly reducing population short-term, population replaced through compensatory breeding or migration from other locations
Combined CNR and responsible ownership targeted several flows into and between the dog subpopulations: it prevented the street dog population from increasing through births and abandonment, and it increased the adoption of dogs from the shelter dog population to the owned dog population. This combined method had a synergistic effect: neither CNR nor responsible ownership applied in isolation was as effective at reducing street dog population size
The key result of this thesis is that methods targeting multiple sources of population increase, such as combined CNR [capture-neuter-release] and responsible ownership campaigns, will be most effective at reducing free-roaming dog population size
You were claiming that this is not effective because people are buying dogs as pets and abandoning them.
Do you understand this thread is about Bhutan? It's a pretty poor country (source below) where not that many people think of buying a dog and then abandoning it.