interested123's picture

Bat box eggs 1 and 2

Observed: 4th November 2012 By: interested123
bat box eggs 1
bat box eggs 2

Abandoned nest in a bat box at Haigh County Park, Wigan. Saw five such nests while checking bat boxes, one with baby bird skeletons. This nest had two intact eggs, one broken. Twig and moss nest was lined with down and a few brown feathers. Suspect small mottled eggs could be nuthatch, treecreeper or blue tit; not sure.

Species interactions

No interactions present.


ophrys's picture


Given the bat box construction, I'd have thought that Treecreeper was more likely...or a Tit.


My Flickr photos...

The Black Rabbit's picture

Interesting. I immediately

I immediately thought blue tit looking at the photos (no text) but on reading the text, yeahhh.... could well be nuthatch I guess.

1p = 20mil diameter.
Blue tit egg size = 16 by 12 approx.
Nuthatch egg size = 20 by 15 approx.

Maybe you could measure them, but even that wouldn't be defintive...

Many thanks,

The Black Rabbit's picture

And equally, as ophrys has

And equally, as ophrys has said, if it was a typical bat box, treecreeper seems very plausible indeed (same egg size as blue tit)

Many thanks,

David Jardine's picture


What was the nest lined with? Information on this will help distinguish between a Nuthatch nest and other species? Similarly, was there any sign of mud around the entrance to the nest?

IWoodward's picture

Not Nuthatch...

The BTO "Field guide to monitoring nests" says that a Nuthatch nest has a loose lining of bark flakes or dead leaves of oak and beech, which suggests it's not nuthatch as you've referred to a twig and moss nest lined with down.

Treecreeper fits your description best ("mainly bark strips, also grass, moss and rootlets, on foundation of twigs, stems and wood chips; rounder cup lined feathers, finer bark strips, spider cocoons, hair, wool").

It could possibly be Blue or Great Tit. Blue tit has used a bat box in my local wood entering via a hole in the corner. However, we have a number of bird boxes that we empty annually in my experience these are mostly made of moss and grass/other vegetation and don't normally have twigs. The BTO nest guide mentions thin bark strips for Blue tit and roots for Great tit but doesn't mention twigs for either species.