Snakes predating bird nests, Europe. (1 Viewer)

[KnockerNorton]

Is anyone aware of any documented evidence/papers of northern/western European snakes (Grass Snake, Adder) predating nests of birds, i.e. entering a tree hole, nestbox or cavity and taking eggs, young or adults?

 

[Xenospiza]

According to my guide (Arnold, Burton and Ovenden) Grass Snakes are known to eat nestlings, but I can't imagine them climbing after them – and certainly Adders (feed mostly on mammals) or Smooth Snakes (lizards) wouldn't climb after birds either.

Western Whip Snake and Aesculapian Snake reach central France and are real climbers – so they'll eat (mostly) young birds given the chance.

 

[davewalters]

Haven't personally observed this behaviour although a year or two ago I found a Wrens nest in a small holly bush. The nest was completely unusual for Wren and was basically an open cup - an adult bird was seen feeding the nestlings. This nest was actually in the middle of a very dense poulation area for Grass Snakes and on several occasions before and after I've seen Grass Snakes in this bush climbing higher than the nest. They quite regularly climb several feet. I assumed that perhaps the Wren had had nestling/eggs taken before and had built a less enclosed nest to enable easy escape if it happened again - no proof whatsoever but thought it may be of interest.

 

[KnockerNorton]

Thanks,

I was thinking in terms of Marsh Tit or Willow Tit nests, which are often very low down (sometimes ground level, more commonly anything up to 4m), and potential nest predators that the species might have evolved to cope with. The nests are in narrow cavities, and get predated by things like weasels, woodmice, yellow-necked mouse, fat dormouse. Was just wondering if snakes should be on the list too. I suppose that they would opportunistic predators, e.g. if finding an accessible nest by chance, rather than a regular predator? So grass snake would be in the same league as, say, a badger, rather than in with the weasels and mice?

Do you have any info on the French snakes, Xenospiza? Their range will overlap with the tits.

 

[Brosnabirder]

Hi Poecile.

This doesn't relate to hole nesting birds but you may find it of interest.
Raptors: a field guide to survey and monitoring, by Hardey et al, The Stationery Office, Edinburgh, 2007, p.160 states "In heather, adders may make use of merlin nests for shelter in the long heather and, when disturbed, may strike and kill chicks and possibly also adult merlins."

That sounds a little speculative but there is a reference for this
Shaw, G., (1994) Merlin chick killed by Adder, 'Scottish Birds' 17, p.162

Sounds like it may be an unusual occurence

 

[Mike Richardson]

Adders most certainly can climb in search of prey, although ground mammals like voles form most of their diet. I have read about Adders eating the eggs of Nightjar and other ground nesting birds.
I see no reason why both Grass Snakes or Adder wouldn't enter a low cavity or nest box to predate young or eggs. Both snakes are great opportunists.

 

[Xenospiza]

An article about nest predation on Japanese parids is found here: http://www.jstage.jst.go.jp/article/aez/40/4/575/_pdf
Elaphe climacophora, a relative of the Aesculapian Snake, is apparently quite a predator!
I guess you might be interested in this (I don't have these – sorry!):
Food Habits of the Aesculapian Snake, Elaphe longissima, in Central Italy: Do Arboreal Snakes Eat More Birds than Terrestrial Ones?
Luca Luiselli, Lorenzo Rugiero, Journal of Herpetology, Vol. 27, No. 1 (Mar., 1993), pp. 116-117
Evolution of Hole-Nesting in Birds
Thomas Alerstam, Goran Hogstedt, Ornis Scandinavica, Vol. 12, No. 3 (Dec., 1981), pp. 188-193

 

[KnockerNorton]

brilliant, cheers.

 

[Farnboro John]

I've seen film of Adders climbing quite high (couple of m anyway) in Hawthorn thickets. The researcher - it was an old lady with a complete photographic record of her local Adder population - certainly thought they were up there hunting.

John

 

[jurek]

Adders certainly eat ground-nesting nestlings: yellowhammers etc. I would guess they can climb a short way. About grass snake, I read both yes, eats nestlings and not, never. Esculapian snake is well known climber and bird eater.

 

[MlZad]

Grass Snakes eat a wide variety of things: frogs, toads, fish, newts, tadpoles, sometimes small mammals, slugs, nestling birds, other snakes, even salamanders. Young feed mainly on tadpoles and invertebrates.
So, they can eat mammals, birds, slugs and reptiles, but if amphibians (and fish) are available, they'll eat those instead.

Also, yes, the Aesculapian snake can climb very well and is known to eat birds. One has even been documented of constricting a bat, but didn't eat it. The people that saw this think it didn't eat it because they disturbed it.

French snakes that would eat birds (and eggs):
Western Whip Snake (Hierophis viridiflavus), Ladder snake (Rhinechis scalaris), Aesculapian Snake (Zamenis longissimus), Grass Snake (Natrix natrix), Asp Viper (Vipera Aspis), Adder (Vipera berus), Seoane's Viper (Vipera seoanei) and Montpellier snake (Malpolon monspessulanus)

 

[KnockerNorton]

Grass Snakes eat a wide variety of things: frogs, toads, fish, newts, tadpoles, sometimes small mammals, slugs, nestling birds, other snakes, even salamanders. Young feed mainly on tadpoles and invertebrates.
So, they can eat mammals, birds, slugs and reptiles, but if amphibians (and fish) are available, they'll eat those instead.

Also, yes, the Aesculapian snake can climb very well and is known to eat birds. One has even been documented of constricting a bat, but didn't eat it. The people that saw this think it didn't eat it because they disturbed it.

French snakes that would eat birds (and eggs):
Western Whip Snake (Hierophis viridiflavus), Ladder snake (Rhinechis scalaris), Aesculapian Snake (Zamenis longissimus), Grass Snake (Natrix natrix), Asp Viper (Vipera Aspis), Adder (Vipera berus), Seoane's Viper (Vipera seoanei) and Montpellier snake (Malpolon monspessulanus)

Would these species enter tree holes, where tits nest, or just predate open nests like finches and warblers?

 

[MlZad]

Would these species enter tree holes, where tits nest, or just predate open nests like finches and warblers?

The Aesculapian Snake (Zamenis longissimus) and the Ladder snake (Rhinechis scalaris) are excellent climbers. I know for a fact that an Aesculapian Snake can climb up vertically on tree trunks and they're skilled at climbing even smooth branches. And I know that several years ago a neighbour of mine saw 3 in a bird house they made, when he climbed up to clean it...

The rest can climb, but only in dense bushes (or something similar), and they're still not so good at it...

 

[Keithec]

Where I lived as a child (Surrey heathland) I was often told that grass snakes will eat birds eggs (& presumably nestlings). I have never actually witnessed it (but then I have rarely actually witnessed a snake eating anything in the wild!) but I did often as a child see a grass snake in a tall hedge close to where I lived. I have even got an old B & W photo of it that I took on a box camera.

Keith