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Sparrowhawk eating Sparrowhawk (1 Viewer)

I was once told that females will kill their mate if he isn't bringing in enough food for the young on the nest...

Jon

Pretty poor survival strategy that (if true). A poor male brings in more food than a dead one.

I'd have thought, as with other raptors, if there isn't enough food for the whole clutch, the large chicks would eat the small ones until the balance is reached between a full crop and the nest population size.
 
I've heard of this before but never seen any pictures of it actually happening. It's obviously a rare sight to behold. Amazing though.
 
Pretty poor survival strategy that (if true). A poor male brings in more food than a dead one.

I'd have thought, as with other raptors, if there isn't enough food for the whole clutch, the large chicks would eat the small ones until the balance is reached between a full crop and the nest population size.

It would seem so but as with every rule there are exceptions and blurred edges so I would not be surprised if females lose patience with a poor hunting male. However, these things can also be difficult to pin down with any certainty and she could be killing an unpaired male that potentially posed a threat to her brood or had chased away her own male.

It is true that birds of prey mostly produce more young than will fledge and 50% loss (or greater) of young is normal for any year with total successes being a very infrequent occurrence. As Barred says, the smallest young are usually first to go but it is interesting to note that a female will often try to raise a brood in the absence or after the loss of a male. Therefore, there is enough scope for plenty of blurred edges or put another way, individual case way beyond the norm.
 
It always amuses me how we anthropomorphise everything. A dead animal is just protein and fat and minerals. What we think of as cannibalism and taboo is just eating food. There are reasons why cannibalism is taboo in humans: we're social animals and hunting each other for food hasn't worked in evolutionary terms or we'd still do it today. Due to the temptation to hide murder as carrion we revere our dead and do not eat them. Many animals do not need to share these scruples. Perhaps the male died and was carrion. If the female was hungry why shouldn't she then eat him? She didn't "love" him. She has no clear idea of him as a cherished member of her own species and therefore off limits. She's not a person.

Her predatory instincts will be lessened if he is breeding with her but if he's another bird he's a useful mate, competition to be driven off or killed, to be feared as a predator or equally matched rival or he's prey. If he's not a useful mate then he's not ticking any of the other boxes. Perhaps she berated him for something, he fought back and she killed him in the ensuing spat. Why then not eat him? Perhaps he was a male who wouldn't take no for an answer and was killed because he refused to be driven off.

Having not witnessed the whole incident it's pure speculation, but she's a bird, not a person, and eating some dead creature is perfectly sensible if you're a bird of prey.

As to whether it's a good survival strategy in evolutionary terms: time will tell. Either her genes will be passed on or they will not. If her offspring by that male were dying anyway because he was useless perhaps taking him out removes his useless genes from her offspring and creates a vacancy for other male Sparrowhawks who are more useful to move in. In the long run maybe this behaviour will select in or maybe it will select out. That's the way it works. Animals do not think and choose survival strategies, they try them out and they either work or they do not. The survivors after generations are testament to the ones that work.
 
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Mikfoz - I bet you didn't even cry at Bambi did ya??!! ;) (U know, when the artist stopped drawing his mum!):-O:-O
 
Slightly different scenario perhaps, as the male can't escape, but it's not unusual for female Eurasian spars to kill the musket in captive breeding projects. Same goes for northern gosses. Some pairs just don't get on - falcons simply don't produce eggs if the pair isn't compatible, whereas female accipitors tend to treat their potential partner as a potential meal . . .

Jonathan
 
It always amuses me how we anthropomorphise everything. A dead animal is just protein and fat and minerals. What we think of as cannibalism and taboo is just eating food. There are reasons why cannibalism is taboo in humans: we're social animals and hunting each other for food hasn't worked in evolutionary terms or we'd still do it today. Due to the temptation to hide murder as carrion we revere our dead and do not eat them. Many animals do not need to share these scruples. Perhaps the male died and was carrion. If the female was hungry why shouldn't she then eat him? She didn't "love" him. She has no clear idea of him as a cherished member of her own species and therefore off limits.

I am not sure anyone posted anything here with the deliberate intention of being anthropomorphic but it can be a useful tool for understanding animal behaviour providing we also understand that these thought processes are not a reality.

An interesting comment about the male becoming carrion because there is some evidence that most sparrowhawks will not scavenge except in unusual circumstances or unless returning to a part eaten kill. I think it was Ian Newton's monograph that describes a sparrowhawk chasing a great tit and passing a winged collared dove that would have been an easier target and a bigger meal. Similarly, I watched a sparrowhawk select out a great tit from the feeders (it subsequently missed) despite an unwary blue tit being closer (the latter did not even spook until the hawk had passed).
 
I am not sure anyone posted anything here with the deliberate intention of being anthropomorphic but it can be a useful tool for understanding animal behaviour providing we also understand that these thought processes are not a reality.

An interesting comment about the male becoming carrion because there is some evidence that most sparrowhawks will not scavenge except in unusual circumstances or unless returning to a part eaten kill. I think it was Ian Newton's monograph that describes a sparrowhawk chasing a great tit and passing a winged collared dove that would have been an easier target and a bigger meal. Similarly, I watched a sparrowhawk select out a great tit from the feeders (it subsequently missed) despite an unwary blue tit being closer (the latter did not even spook until the hawk had passed).

I was referring more to the linked web site where the commentator cites his "somewhat horror" at the sight.

It would appear, however, that this is in fact not uncommon.


With regards to the hunting behaviour: Sparrowhawks (and indeed all hunting falcons) are a bit like a guided missile in terms of locking onto prey. Their peripheral perception in these instances is a bit like us looking down a scope and tracking something. It won't have even registered the non-selected prey items (who knows why it made the original choice?); the only purpose for the rest of its vision is to avoid collision with obstcales, a process largely handled by the unconscious mind. They may lose lock and miss their prey but what they cannot afford is a thoughtful disposition that allows for distractions. This is why Starlings flock in order to distract and fuzz out the lock on and prevent it taking place.

I'd suggest this to explain why it appears so single-minded on its prey in the quoted scenarios.

As for eating carrion, I await being corrected with data but pretty much all predators will eat carrion if it's available. The trick is finding it, which something like a vulture is equipped to do. Sparrowhawks are geared up to detect moving live prey and are therefore more likely to find this. I can't see one turning its nose up at a dead Sparrowhawk it can't miss, should the opportunity arise.

The balance of probability is that the male was deliberately killed in this instance, though, I'll grant you - repellent though this option is to our human concepts of murder and cannibalism.
 
The fact is nobody could really say for sure what went down. The Sparrowhawk may have just been desperatly hungry, made a mistake, took advantage of the birds possible injury or it may have been one of those extreme scavenging cases.
 
I am not sure anyone posted anything here with the deliberate intention of being anthropomorphic but it can be a useful tool for understanding animal behaviour providing we also understand that these thought processes are not a reality.

An interesting comment about the male becoming carrion because there is some evidence that most sparrowhawks will not scavenge except in unusual circumstances or unless returning to a part eaten kill. I think it was Ian Newton's monograph that describes a sparrowhawk chasing a great tit and passing a winged collared dove that would have been an easier target and a bigger meal. Similarly, I watched a sparrowhawk select out a great tit from the feeders (it subsequently missed) despite an unwary blue tit being closer (the latter did not even spook until the hawk had passed).

Baiting up a plucking post with dead birds, cut up Rabbit carcases or whatever, is a well known method of luring Sparrowhawks in to be trapped, shot, poisoned etc by keepers. It still goes on unabated on most estates.

nirofo.
 
Baiting up a plucking post with dead birds, cut up Rabbit carcases or whatever, is a well known method of luring Sparrowhawks in to be trapped, shot, poisoned etc by keepers. It still goes on unabated on most estates.

nirofo.

Sincerely hope that wasn't the case here. Mikfov is quite right to say we don't know the full 'story', there is no information as to whether the people actually saw the kill. Nor do they say it was taken of their own garden despite being 'from a window' ...

If for argument's sake, a hypothetical female was feeding on a male killed by other means or already weak/sick, can poisoning be gradual or does it always occur immediately ... ie would a raptor (eg. the hypothetical male in this case) who's fed on poisoned carrion suffer immediate death always or could it fly to another location and succumb later? Would another raptor, suffer secondary poisoning from eating the carrion of a poisoned raptor?

Mikfov, I hear what you say and anthropomorphising birds/animals makes me cringe but I'm sure such an approach has done a lot more for raising Conservation issues among the general public than any of our ranting on BF over the years than perhaps we give it credit for ;)

BTW You didn't actually answer my original question as to whether you'd witnessed a Sprawk taking a live Sprawk for food - has anyone? Even Ian Newton professes not to have seen it with his own eyes.

(Ads, Bambi I could just about cope with, but Watership Down, the Plague Dogs and Ring of Bright Water had me weeping buckets)
 
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With regard to poisoning of raptors:

There were two ways raptor numbers were affected by poisoning. The first and most obvious is to purposely lace a carcass with poison to kill the bird directly with an immediate overdose of a toxic substance.

The second way was unintentional as a result of mankind's endless meddling without thinking it through via pesticides/pollution. This works for toxins that do not break down and accumulate inthe bodies of animals such as DDT and heavy metals like lead and mercury. As each stage in the food web is reached there is a gradual concentration of levels in the food eaten at each stage. I'm assuming the basic principle of a food web is understood here (google is your friend). This means that in effect the apex predator is eating the equivalent of several thousand invertebrates by the time it eats the song thrush. So every time it eats one thrush it has taken on the whole food web below it's intake of the poison. Meanwhile, the single thrush only eats its own share and each snail it eats only ingests its own share but it eats thirty snails a week. The snail in turn eats many leaves which each only had their own share. The animals lower down the food web often show no ill effects because they don't ingest sufficient poison before dying of natural causes or being eaten. Meanwhile, our Sparrowhawk, after eating ten thrushes is feeling very poorly indeed....

So in answer to, does our Sparrowhawk eating a bird that was poisoned itself in turn become poisoned: it depends on a few factors.
  1. Does the toxin used break down in the very action of being toxic and is therefore used up?
  2. Is the toxin stored in the tissues of the dead animal or excreted/stored in the gut?
  3. Is it the actual toxin stored in the tissues or the residue of the toxin after taking effect - and is this, in itself, toxic?
It doesn't always follow that a purposely poisoned animal is itself toxic to eat, though experimental eating would be unwise to try. The levels of toxin in the poisoned animal will likely be far lower than in the poisoned bait as this is usually laced with a ridiculous overdose so that even a tiny ingested amount is fatal. This woud then have to be totally ingested by the next creature along, having not been broken down chemically.

Your problem with Owls scavenging poisoned rodents is that they may well ingest a large number of them if a poisoning campaign is particularly vigorous and successful, thereby concentrating the poison.

I'll shut up now.
 
Also, re the anthopomorphising: I hear you ref the raising of empathy towards conservation, but in terms of actually observing natural behaviour; the observer changes the observation all too readily.
 
With regard to poisoning of raptors:

There were two ways raptor numbers were affected by poisoning. The first and most obvious is to purposely lace a carcass with poison to kill the bird directly with an immediate overdose of a toxic substance.

The second way was unintentional as a result of mankind's endless meddling without thinking it through via pesticides/pollution. This works for toxins that do not break down and accumulate inthe bodies of animals such as DDT and heavy metals like lead and mercury. As each stage in the food web is reached there is a gradual concentration of levels in the food eaten at each stage. I'm assuming the basic principle of a food web is understood here (google is your friend). This means that in effect the apex predator is eating the equivalent of several thousand invertebrates by the time it eats the song thrush. So every time it eats one thrush it has taken on the whole food web below it's intake of the poison. Meanwhile, the single thrush only eats its own share and each snail it eats only ingests its own share but it eats thirty snails a week. The snail in turn eats many leaves which each only had their own share. The animals lower down the food web often show no ill effects because they don't ingest sufficient poison before dying of natural causes or being eaten. Meanwhile, our Sparrowhawk, after eating ten thrushes is feeling very poorly indeed....

Yes, I understand the basic principle of the slow accumulation of ingested toxins in the food chain, our Peregrine populations were particularly devastated in this manner - (but thanks anyway!)

However, none of this is directly relevant to a situation where a raptor (rarely I presume since apparently no or few people have witnessed it) takes a live raptor as in my hypothetical case of the Female Sprawk taking a male that has itself ingested poison.

So in answer to, does our Sparrowhawk eating a bird that was poisoned itself in turn become poisoned: it depends on a few factors:

Does the toxin used break down in the very action of being toxic and is therefore used up? Is the toxin stored in the tissues of the dead animal or excreted/stored in the gut? Is it the actual toxin stored in the tissues or the residue of the toxin after taking effect - and is this, in itself, toxic?

Well this was the actual question I raised but which you answer with more questions in fact those I wanted answered when posing the question!


It doesn't always follow that a purposely poisoned animal is itself toxic to eat, though experimental eating would be unwise to try.

I'm not sure I understand that comment

The levels of toxin in the poisoned animal will likely be far lower than in the poisoned bait

Well that probably stands to reason but again doesn't answer my question as to whether a Sparrowhawk will be (fatally? seriously?) poisoned by eating one Sparrowhawk that itself had fed on poisoned bait (a baited Spar or otherwise).

Your problem with Owls scavenging poisoned rodents is that they may well ingest a large number of them if a poisoning campaign is particularly vigorous and successful, thereby concentrating the poison.

Again more relevant to the scenario of a BoP eating poisoned bait directly and/or accumulation by quantity of poisoned bait being digested over a period of time. Obviously s Sparrowhawk's main diet isn't other Sparrowhawks, so slow accumulation through the food chain by secondary poisoning in the form of other Sparrowhawks who've eaten baited prey (baited Spars or otherwise) is probably irrelevant to the scenario I outlined.

My question followed on from the comments Nirofo made regarding BoP being used as bait and whether a Sparrowhawk taking another Sparrowhawk which itself had fed on a deliberately baited Sparrowhawk and had survived long enough to have been taken as live prey itself. Which brings me back to the original question and the point of the link in the first post/ Ian Newton's comments:

That is: Whether anyone has actually witnessed a Sparrowhawk taking live Sparrowhawks as prey?

I agree 'google' can be 'your friend' but whatever snippets found need still to be put together in a way that's logical and relevant to the question being asked ;)
 
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Also, re the anthopomorphising: I hear you ref the raising of empathy towards conservation, but in terms of actually observing natural behaviour; the observer changes the observation all too readily.

I'd certainly agree with that! (I was thinking more in terms of eg. giving Osprey names and calling them ''Mr and Mrs'' etc ;))

Sometimes it's about language used to describe 'natural behaviour' that can come across as a little anthropomorphic LOL

''Perhaps she berated him for something, he fought back and she killed him in the ensuing spat. Why then not eat him? Perhaps he was a male who wouldn't take no for an answer and was killed because he refused to be driven off.''
 
It doesn't actually follow that an animal that has been itself poisoned is now poisonous to eat because often the toxin itself is destroyed in the reaction that caused the death.

Without actually knowing what poison was used it's impossible to say.

Also, the concentration levels of poison in the poisoned bird will be much lower than in the bait as they have been spread throughout the entire bird, which must be larger than the bait ingested.

Unless the poison is particularly virulent and the overdose was massive and it stays unchanged in the body, eating the carcass may well be harmless.

I know that doesn't entirely answer your question, but it really does depend on a lot of variables. It's probably less hazardous for her to not eat one that had been poisoned, however and it could, potentially, kill a second bird in these circumstances.
 
mikfoz said:
It doesn't actually follow that an animal that has been itself poisoned is now poisonous to eat because often the toxin itself is destroyed in the reaction that caused the death.

For one, what I have heard is that warfarin is applicable for grey squirrel control because it tends to degrade very quickly after it has 'done its work'.
 
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