This question mostly relates to wild pigeons. Feral pigeons are opportunistic feeders and will eat almost anything and that includes spiders.
Pigeons and Spiders
For a normal-sized pigeon, any spider on the small side that they will find on the ground or on tree bark is pretty much up for grabs.
The limitations of a pigeon’s beak mean that they can only really handle food that can be picked up whole like grains and seeds or are soft and easily broken apart.
What this means is that you shouldn’t expect to see a pigeon feasting on a tarantula anytime soon! Not only are spiders like that way too big to attack and actually feast on by a pigeon, but depending on what part of the world we are talking about some big spiders might be in the mood to actually fight back!
Pigeons are nowhere near the top of any food chain, and that means that they are not naturally the aggressors or hunters in any given situation. There is a huge difference between pecking at a small spider and going for a huge tarantula, and pigeons will definitely be averse to attempting the latter!
Are Spiders Good for Pigeons?
So, besides being attractive moving targets, are smaller spiders actually beneficial to pigeons in a dietary sense? The answer is yes!
It is hard to make anything other than generalized statements about a spider’s nutritional value because there are 45,828 described spider species. No one knows how many there might actually be. In the UK, it is estimated there are 650+ species of spider compared to 3,500 species in the USA.
It might be said that spiders are the equivalent of an energy bar for pigeons (and other birds).
Being rich in protein, folic acid and zinc, spiders provide a healthy snack.
Spiders contain large amounts of an amino acid called taurine, and this can be extremely beneficial for birds. So beneficial, in fact, that adult pigeons will often find spiders and take them to feed their babies to encourage their healthy growth.
Taurine is a common ingredient in energy drinks for humans, so on an equivalent level, pigeons on a long flight could replenish their energy supply with a snack of a few spiders.
There is also anecdotal evidence that pigeons have been seen eating spider webs although there has been little scientific comment on this behaviour.
Domesticated Pigeons vs Wild Pigeons
The diet of a domesticated pigeon is far more regimented than that of wild pigeons.
Domesticated pigeons are fed by their owner and there’s usually enough pigeon food so that if they are let out for a fly about, it’s unlikely they’ll look for a main meal.
Wild pigeons do not have access to a regular food supply so will always be on the lookout for something to eat – anything they consider edible is fair game when it comes to what pigeons eat.
Pigeons can and do eat spiders but there’s no real evidence that means you need to fill your bird feeders with them anytime soon. Pigeons will make their own minds up as to whether they will eat any spider that happens to cross its path.