Dead blue tit chicks (1 Viewer)

[Wickham]

Blue tit chicks have died just a day or two before leaving the nest box and I wonder why.

Great tit chicks of almost the same age have just left their nest box.

I've just cleaned out both nest boxes. The blue tit box is on the wall of my house under wide thatched eaves and gets a lot of sun. The nest was bone dry and the chicks fully grown.

The great tit nest box is on a the north side of a tree trunk heavily covered by leaves and was soaking wet inside with small grubs under the nest material, but those chicks survived.

I have a bird board with a mixed bird food only yards from the blue tit box and the parents used to fly a quick shuttle service to and from the box as soon as I refilled the bird table, but so did the great tits, (and robins, chaffinches, dunnocks and blackbirds).

It's possible that they were being overfed and I don't suppose that bird seed is the correct diet. They generally only took nuts and small grains, leaving larger seeds and maize flakes, but the great tits ate the same food, concentrating more on nuts I think. Both sets of parents fed their chicks other food as the bird table was often empty and replenished at breakfast, lunch, afternoon and evening when there was an immediate rush of several lots of parents.

Why the great tit chicks survived but the blue tit chicks did not is a mystery.

 

[Sancho]

I think the advice is not to place a nest-box where it'll get too much sun. Any nest I've inspected in a nest-box after successful nesting has been damp at the bottom, with grubs and debris and the occasional unhatched egg or dead chick. Maybe (and I'm no expert here) your bluetit nest was too exposed to heat and light...maybe the chicks need a little bit of moisture, and they may well need those grubs too in the run-up to leaving the nest. Just guessing!

 

[KnockerNorton]

There could be several reasons.

One is that the parents(s) have been killed (Sparrowhawks take many breeding birds). Blue Tits not infrequently breed as trios, with a male and two females, so many nests have only one female feeding them. If she's killed, they've had it.

Secondly, it could be starvation due to the recent heavy rain. Tits in gardens are not in their preferred ideal habitat, and chick food is often in short supply. Great Tits can often do better as they can forage on the ground and take a wider range of prey, but blue tits need caterpillars, and then turn to aphids in desperation. If they're taking artificial food then they're REALLY desperate and not finding natural food. We're past the caterpillar peak now and chick food is on the wane. As the chicks reach fledging they need the maximum amount of food, so if they're going to starve then now is the time.

And that takes me to the third possibility. You say the adult was shuttling back to feed them with seed. This is very low is water, and chicks get all their water from the juicy insect food. If they're being fed seed then they may have died from dehydration.

 

[Wickham]

Both parents were alive; the nest box is in sight of my kitchen window and I could watch both parents collecting food from the bird table and flying straight to the nest box.

I was aware that there was a problem when one parent flew to the box but flew away without going in.

I don't remember ever seeing a parent with a juicy caterpillar (I have a country garden with mixed hedgerows, trees, shrubs, etc.). After using the bird table they would fly around and return to the nest very frequently, sometimes within 30 seconds, but could only have caught a small fly or midge.

I also think that the combination of a hot nest box and the wrong food must have dehydrated the chicks.

 

[KnockerNorton]

I don't remember ever seeing a parent with a juicy caterpillar (I have a country garden with mixed hedgerows, trees, shrubs, etc.). After using the bird table they would fly around and return to the nest very frequently, sometimes within 30 seconds, but could only have caught a small fly or midge.

I also think that the combination of a hot nest box and the wrong food must have dehydrated the chicks.

Sometimes they don't exactly help themselves. I'd have stopped putting out other food (or put less of it out, and on the ground for the Robins etc but where Blue Tits wouldn't forage much), to force them to find something better. They may have been restricted by their territory, in that it cut out a lot of the good habitat, or there may not have been much natural food around. Mixed hedgerows should have provided something better than seed, however.

I think dehydration from feeding the wrong stuff would be prime suspect. Unless nestboxes are very thin-walled, the insulation qualities of wood means that they don't really overheat inside, even in full sun, except where the sun falls through the hole for part of the day.

It's quite common for Blue Tit broods to fail though, so don't fret too much about it.

 

[halftwo]

:-CHi W,

I've got a camera box & once again, as last year:
Ten eggs laid.
Eight hatched. (Nine last year)
Both parents very busy feeding - all chicks growing well.
Then: after a week or so, one by one all the chicks die.
Last two to die too big to be removed by (now one) parent, last chick now not looking well while still being fed & growing.
Don't expect it to survive.
During the the rain the parents were finding plenty of food - lots of big juicy caterpillars brought.
The box is east facing - gets sun in am. - had successful broods raised from this location in the past.
Seems to be desease to me - no visible mites/ticks etc. (but parents unaffected)

Not nice to watch & know that tomorrow the end will have come.:-C

H

 

[KnockerNorton]

Seems to be desease to me - no visible mites/ticks etc. (but parents unaffected)

Not nice to watch & know that tomorrow the end will have come.:-C

H

Disease is not something that tends to affect nests, tbh. Also, if it was disease, they'd all die at the same time, not one by one. This sounds more like starvation. They may been bringing in caterpillars, but they need 500 a day for a brood as it approaches fledging. If they can't find them then they the chicks die one by one as the weakest get out-competed.

We are getting pretty late for Tit broods now too. We're well past the 'bountiful food' stage of the caterpillar peak, which came in early May. So many late broods are starving as the tits had quite a broad spread of laying dates this year. I checked some boxes this week and about half were dead/dying. All the successful broods have been fledged for at least a week now, and several tit species have completely finished.

 

[halftwo]

They did start a little later than normal - but I don't think it's starvation because they grow as they die, and as there are fewer & fewer the last should have an ever-increasing chance because they are getting a greater share of available food. And the Great tits are doing OK only thirty metres away.
I was watching the parents stuff huge caterpillars down the necks of birds that died a day or so later - and removing unswallowed food from (presumably sated) beaks.
I don't agree that disease would necessarily kill all affected chicks at once - that's not how pathology works - is it?
Anyway, we'll never really know - unless someone wants to do an autopsy?

 

[KnockerNorton]

They did start a little later than normal - but I don't think it's starvation because they grow as they die, and as there are fewer & fewer the last should have an ever-increasing chance because they are getting a greater share of available food. And the Great tits are doing OK only thirty metres away.
I was watching the parents stuff huge caterpillars down the necks of birds that died a day or so later - and removing unswallowed food from (presumably sated) beaks.
I don't agree that disease would necessarily kill all affected chicks at once - that's not how pathology works - is it?
Anyway, we'll never really know - unless someone wants to do an autopsy?

Well disease isn't passed on like a baton. It's more of a shared experience! Birds have very fats metabolisms, so disease passes and works on them very quickly. If it was a disease, they'd al be dead in a day or two. That it's sequential tells us that it's something to do with competition between the chicks, with the weakest dying first. Remember too that as they grow they therefore need increasing amounts of food, which is diminishing all the time, so x amount will be enough to feed a brood at 5 days, but not enough to feed one bird at 15 days, and x amount will be easier to find at 5 days than 15.

Just a point, when birds remove 'unswallowed' food, this is normal. The adults are squeezing juice down the throats of several chicks, hence they pass it around and the young give it a squeeze in turn. That way, several get fed at once. You also see them doing this when they bring in sunflower seeds, so it's hard-wired behaviour.

 

[deborah4]

Well somethings badly amiss it seems with BT offspring this year and weather is certainly all over the place - my garden is usually full of fledgling Blue Tits at least once during this period. I've seen one scruffy bedraggled individual briefly and no others. (There's a nest box a few doors down and at least one pair usually nests in a large tree next door). This morning, two adults displaying/mating, so it looks like they are attempting a new brood. On the other hand, Great Tits have done very well.

(hopefully no one is putting whole peanuts out!)

 

[halftwo]

Hi KN, (formerly Poecile, (I note) - why the name change?),
Hi Deborah,

I know what you mean re the exponentially-increasing food amounts needed & I know that it's normal for food to be removed from beaks - assumed this was a behaviour to spread the wealth - didn't know about the juice-squeeze thing KN - you have some extraordinary knowledge there - care to share where this comes from? Are you a parus expert through work study or from years of in-depth knowledge gained from a specialist interest?
Thinking about my comment re growing & dying - I could be wrong here I suppose - could the hard-wired 'need' to grow even while starving give me a false impression of things appearing better than they really are? (The camera makes it difficult to judge relative sizes of individuals as the foreshortening effect is very pronounced over a few inches.)
And if it is starvation - would it have been possible to provide supplementary food (say mealworms) at a convinient location?

Deborah,
I don't think that, weather-wise at least, this year is exceptional - and many other species seem to be OK (though, of course, I don't have cameras in other nests) - but I've seen, like you, young Robins, Dunnocks, Lt tits, Rooks, Woodpigeons, etc. & several spp. are on second broods already. It's a shame that some spp. only get one chance a season.

Anyway - whatever the cause: the cause is lost - last one died today. Am really upset again. That's a lot of effort & energy wasted - especially if it's the same pair that failed last year.
Another sad nestbox clearout ahead.

H

 

[cjay]

The Blue tits have suffered on my local patch and it has been observed in other places. Normally it is cold,lack of food or natural death.

 

[KnockerNorton]

care to share where this comes from? Are you a parus expert through work study or from years of in-depth knowledge gained from a specialist interest?

The former. Parids are the best studied group in the world, and there are lots of people working on them.

If you handle them you can tell if they're starving as they are obviously scrawny. Weighing them tells you so too. It can probably be hard to tell from a video image with an untutored eye. Mealworms may have helped, but they're not cheap and there are millions of Blue Tits, and you can't mollycoddle them all their lives. They are only nesting in such marginal habitats (gardens) cos they are overspilling from their core habitats, so don't fret too much. They were always a reserve brood, and stood little chance of getting established anyway.

 

[halftwo]

Thanks KN,
Seems odd though - I've had nestboxes in the garden (adjacent to wood & lots of oak, ash, elm here) for 15 years & don't remember clearing out multi dead chicks post breeding season. The Great tits seem OK in the other box, and we've had worse weather in other summers.
H

 

[KnockerNorton]

it all depends on their relative timing though. Many birds judged it wrong this year, and missed the peak food abundance. Also, Blue Tit numbers have increased a lot, so the territories may now be smaller, as they're more tightly packed in, and your garden birds are excluded from the best foraging in the wood. Lots of possibles.