thinfor

I think it depends on how the photographer thinks when he/she was taking the photos.  

I do have a different aspect on whether the cat belongs to the nature or not.  Actually, I don't understand why this cat is not belonged to nature...you mean because it's captive or it's not an actual wild animal (as you pointed out the leopard cat)?  If that cat has become wild (that means no one owns the cat), hasn't it required to feed itself (Actually I don't think cat will target a bird for food)?  I have dogs...I can tell you the dogs usually chase the birds and their action may have different meanings but usually they do it naturally - curiosity, in-born to chase the creatures smaller than them.  I think cats also have similar behaviour as well.  They may not really mean to hurt the bird...just want to chase it and see whether it can be achieved.

I think cats chasing creatures (including birds) happen anytime and anywhere.  This time Swing took the shoots and I think what he meant was to RECORD and shared what HE HAS SEEN at that moment.  The issue may be focused on whether the magpie can be protected and photos should be taken before doing this.  Let me put in this way - if you see a cat looking daggers at a bird, what would you do?  Will you really immediately stop this by frightening the cat?  If you do this, have you frightened the bird as well?  And if you do do not frighten the bird but just the cat, will that a very good act to the cat?  If the cat is owned, I don't think the cat owner will be happy about that because you frighten his/her 'baby'.  If you do just frighten the bird, not the cat, you just replace your position from the cat only!  The difference is just that you will not hurt the bird, but to the bird, it was still being frightened...or you think the magpie can tell you are saving its life?

I think we should be fair to all creatures in the world and show respect to them.  I have dogs so I may have bias to dogs.  I like watching birds so I may love birds more than cats.  But the photos, to me, are just showing the nature that will normally happen.  I respect Swing's share.  I don't think he wanted the magpie to be killed or wanted to photo some good stuff without considering the possible outcome in this situation.  He just had a different point of view at that moment.

Catching a bird is not easy at all.  Even cats are very swift, it could hardly catch a normal healthy bird.

thinfor

First of all, I am not sure whether I have interpreted the meaning of 'feral' correctly.  I think 'feral' means wild, untamed and brutal.  In this case, I refer mainly to those HK street-wandering cats and dogs that are not owned by anybody.  Also, you have quoted some homepages mentioning 'invasive species' and I am not sure whether they can be classified as invasive species.

To me, I think we should first blame ourselves for having dog and cat (and other animals) trades, before pinpointing that feral animals are pests.  Long long time ago, when dogs and cats were not being commonly treated as our pets, they were also wild and people at that time just discovered their strength in scent and other hunting behaviour so they became mainly WORKING dogs and cats.  They had become good working companions and further they become pets.  Would those working dogs and cats be called as feral animals?  I'm unsure.  (As you said the cat is feral, it's not a part of a nature.  I also cannot share your view.  All the incestors of dogs and cats should also belong to nature but somehow they could help humans' lives and so they are closer with humans and then feral dogs and cats occur as a result if badly treated.  Not so many animals can be like cats and dogs that have this kind of close relationship with humans.)

I also don't want to see feral animals attacking wildlifes.  However, please don't forget that those feral animals are also victims and the reason behind is we, human beings, are selfish.  Some people would like to have pets for joy but somehow they change their mind easily when they think the pets are not important anymore.  Consequently, they then become feral and this outcome was a bad one that we really don't want to see it.

When I found out that I bought dogs is just indirectly encouraging pet business, I am not going to do it again since not everyone may have the same mindset and be responsible to keep their pets until their death.  If I really want to have pets next time, I'd rather adopt them.

I agree that feral animals, as you said, may be pests (you have quote quite a few examples and I needn't waste time to argue with it) but I, myself, feel it's too embarassing to judge or label them as pests since we, human beings brought them to this situation!  We're also just tiny creatures in our big galaxy and I believe that we are also pests indeed.  The extinction of animal and plant species, the pollution we've made, the greenhouse effect, etc, have proved that we have endangered and even made many species extince.  We are more advanced and superior so we can value other creatures and would not be objected.  But nature should not be seen in this way.  Have you heard what Dr Chow Siu Cheung said about the pests that destroy the crops?  He said this is the nature.  Even human beings are so advanced to invent pesticides to kill pests, the proportion of crops being destroyed before and after the pesticides had been invented is the same, around 30%.  The nature includes all the organisms.  They have their own life cycles but they are interrelated.  Lives find their way.  If it doesn't seem to happen, it's probably we're trying to change the world too much.  The case of feral animals is definitely an example.

How about deeply think twice again how bad we human beings have done to the nature first?  Should we complain the owners who quit keeping the pets instead of labeling those cats and dogs 'feral' and not belong to nature?  You have quoted many links related to ecology.  Then you probably should know ecology more than I do.  So human impacts is a big issue to the ecology, do you agree? And for the homepage of top 100 invasive species, if human is counted, it must be the first invasive species!  

All my dogs have been well trained by dog trainers.  So no worries.  Dogs can be trained as a weapon (especially big dogs) so a certain level of training is required.  As a dog owner, this is the responsiblity.  I know this but in HK just not many dog owners have this kind of concept.  Education is required for those who want to have pets.

Just my sharing.  Sometimes, when my dogs are unleashed on grass, they just run and play.  If they see some birds, they do run to chase the birds but their behaviour is different and unique from each other...sometimes they even can't notice the birds even at a very close distance!  But as they are trained, they are tame and don't want to attack the birds.  You can tell from their eyes, poses and gestures.  The phenonmenon is just like a child chasing the pigeons and tree sparrows in the park!

Back to feral animals...in order to lessen feral animals in HK or even the world, human mindset has to be changed with adequate education.  For the existing feral animals right now, ethical concern is involved.  Killing is one way but I don't think it's the best way.  SPCA has suggested to desex them such that there will be no more offsprings once the existing generation has died.  

Those feral animals cannot choose their fate.  We humans are in charge.