Hi, this is originally an answer to a comment on reddit in a thread about effective ways to donate, since it took me a long time to research and write this answer, I wanted to also post this here, in case more people are interested. You can find the original comment/thread here: https://www.reddit.com/r/VeganActivism/comments/1fw2ipk/comment/lqcxkop/?context=3

First of all, looking for the average cost to care for animals, I’ve found numbers between 6,6€ (1) to care for a chicken for one month at a sanctuary up to 60€ (2) to care for a chicken for one month at local sanctuaries here in Austria.

If we roughly assume that on average it costs 20€ to care for one chicken, and that chicken live on average for 7 years, that’s roughly 1700€ to provide a home for one chicken at a sanctuary.

For cows I’ve found a number of 500€ per year at a local sanctuary here in Austria (3), with cows having a live expectancy of 20 years, thats 10000€ to provide a home for one cow at a sacntary.

These estimates might be way too low, as I’ve also found sources saying it costs on average 3000€ for a pet shelter to look after one animal for one year (4). A farmed animal sanctuary is of course not a pet shelter, but I would hope they provide at least as good care as pet shelters do, so the cost would likely be at least as high.

From my own estimation of the cost to turn one person Vegan which you can find fully sourced here (5), a ahighly effective public awareness campaign like Veganuary can turn one person Vegan for every 121€ donated.

Most Vegan calculators I’ve found assume going Vegan saves on average 1 animal per day, for example (6), now how many animals this spares in total of course depends on if the person would have gone Vegan anyways, and also on if the person stays Vegan permanently, lets take a conservative/pessimistic approach and assume people on average only stay Vegan for one year (7), meaning a donation of 121€ to Veganuary would save 365 animals, or roughly 3 animals per €.

This means donating to Veganuary would save 5100 times more animals than adopting a chicken at a sanctuary, and would save 20000 times more animals than adopting a cow at a sanctuary.

For another example I’ve found here (8) donating one dollar to corporate cage free campaigns will affect 9 to 120 years of chicken’s lives, donating to these campaigns, you could affect between 15300 and 204000 years of chicken’s lives for the same cost as housing one chicken at a sanctuary.

Some sanctuaries also do outreach such as allowing non-Vegans to visit them and posting about their animals on Social Media, which might influence more people to go Vegan. Even so, I’ve not found any survey that had sanctuaries anywhere near the top reasons why people go Vegan. If we go by this survey (9), 370 people in 2019 said they went Vegan because of Veganuary, and Veganuary spent 1,4 million punds of 1,7 million € (10) in 2019, while sanctuaries show up twice in the survey and might at most account for 104 Vegans in the survey. This means, to be as cost effective at getting people to go Vegan as Veganuary, all animal sanctuaries in the world combined would have had to spend less than 500000€ in 2019, which is obviously not the case.

Seeing how more than 90% of money donated towards animals goes to shelters (including pet shelters) (11), I think our movemnt needs to drastically redirect resources away from sanctuaries/shelters and towards highly effective organizations, where the same donations can have thousands or tens of thousands of times more impact.

This is not to say that if you have a partnership for an animal at a shelter, this has no value at all. If this partnership is what keeps you motivated to continue fighting for animals and what keeps you inspired to donate more for animals, by all means, please continue that partnership. But please donate the vast majority of the money you are able to donate to animals towards highly effective charities where it will have between thousands and tens of thousands of times more impact.

For some ideas where to donate, I’ve already mentioned Veganuary:
https://veganuary.com/
besides them I would recommend the Recommended Charity fund by Animal Charity Evaluators: https://animalcharityevaluators.org/donate/
aswell as the Effective Altruism Animal Welfare Fund: https://funds.effectivealtruism.org/funds/animal-welfare

Finally, I want to acknowledge that I am using lots of estimated numbers in this comparison, and am comparing numbers from many different years, so these are of course no where near exact results, just rough estimates. I am not trying to say that you will save exactly 5100 times more Animals' lives by donating to Veganuary instead of a sanctuary for example, the difference might be one tenth of what I estimate here, or might be ten times higher than I estimate here, I don't think its possible to know for sure. But I do think if we look at the numbers it is safe to conclude that donating to highly effective charities will have a positive effect that is orders of magnitude greater than donating to a sanctuary. 

Sources:

(1) https://www.hof-sonnenweide.at/unsere-tiere/patenschaften/patenschaft-%C3%BCbernehmen/
(2) https://www.gut-rannerjosl.at/
(3) https://www.lebenslaenglich.at/patenschaften/
(4) https://mieuxdonner.org/why-help-one-animal-when-you-can-help-thousands-with-the-same-donation/
(5) https://www.reddit.com/r/VeganActivism/comments/zinaf9/some_estimationscalculations_on_how_many_people/
(6) https://www.omnicalculator.com/ecology/vegan-footprint
(7) https://animalcharityevaluators.org/research/reports/dietary-impacts/vegetarian-recidivism/
(8) https://rethinkpriorities.org/publications/corporate-campaigns-affect-9-to-120-years-of-chicken-life-per-dollar-spent
(9) https://vomad.life/survey/
(10) https://veganuary.com/wp-content/uploads/2020/12/Accounts-to-29-02-2020.pdf
(11) https://animalcharityevaluators.org/charity-reviews/causes-we-consider/why-farmed-animals/