[Tweeters] Speculation-Re: Grub harvesting?

[Dan Reiff]

Hello both Steves,
Without additional observations, it is difficult to know if what you saw was a food item or a fecal sac.
Here is some additional information.

Hello Steve,
If you observe the Chestnut-backed chickadees again, watch to see if they’re taking food into the nest cavity and then bringing the grub like items out of the nest. If so, what looks like a grub is  likely a fecal sac produced by a nestling. The parent takes the sac away from the nest and drops it at some distance to keep the nest cavity cleaner and not attract predators. 
An adult presents food to the young and then waits to see if one presents a fecal sac.
If the the adults are not bringing food to the nest just before they leave with the grub like thing, then maybe it is a food item.
Now that you mention it, fecal sacs do kind of look like grubs.
They look like tiny off- white, partially filled balloons with a darker end.
Here is a cut and pasted quote from Cornell’s Birdsoftheworld,
Regarding Chestnut-backed chickadees:

Nest Sanitation
Both sexes remove gelatinous film-covered fecal sacs. Sacs are dropped in flight some distance from nest. Sacs removed up to 1–2 d prior to fledging and then accumulate in nest. Ants commonly clean nests after fledging.



I film birds (4K video) and have recorded several species removing the sacs from nests. If you would find it helpful, I can send you a photo of an adult carrying one from a nest.

I would be interested in your additional observations.

Thank you,

Dan Reiff


Sent from my iPhone


> On May 28, 2022, at 10:15 PM, Steve Hampton <stevechampton at gmail.com> wrote:

> 

> 

> A recent webinar on gardening for birds related that chickadees need over 6,000 (!) moth caterpillars to fledge a nest of chicks. The moths generally use native trees (e.g. birch, alder, bitter cherry). I don't know much about moth caterpillars, but that could be what they were after. 

> 

> 

> 

> On Sat, May 28, 2022 at 9:20 PM Dan Reiff <dan.owl.reiff at gmail.com> wrote:

>> Hello Steve,

>> Maybe removing fecal sacs from nest cavity.

>> Dan Reiff

>> MI

>> 

>> Sent from my iPhone

>> 

>>> On May 28, 2022, at 6:56 PM, Steve Platz <stephenplatz at pm.me> wrote:

>>> 

>>> 

>>> We witnessed a couple of Chestnut-backed Chickadees today going in and out of what we assumed was a nest, an excavated hole in a snag maybe fifty feet up. I took a couple of shots when there was activity, and noticed that the two appeared to be exiting with grubs, not entering. We are now wondering if these birds were actually harvesting from the cavity, and not depositing in hungry mouths. At home we've been enjoying seeing a parent CBC coming for suet and feeding three fledglings mouthfuls of cake as they shake in the tree nearby in anticipation. Some are learning to come to the suet themselves, but mostly still preferring to be fed!

>>> 

>>> 

>>> Sent with Proton Mail secure email.

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> -- 

> ​Steve Hampton​

> Port Townsend, WA  (qatáy)

> 

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