This crossword No. 21690 clues and answers were published on Tue 14 Sep 1999 and the puzzle can be visited by following The Guardian Cryptic Crossword No. 21690 link.
All Across Clues and Answers:
5-across – Bird seen on migration in Tresco? : SCOTER
6-across – Birds presented with bill for geranium : CRANES
9-across – Bird with belly-ache : GROUSE
10-across – Giddy dove circling another bird in the air : OVERHEAD
11-across – A bird – or, to put it another way, birds : SKUA
12-across – An eccentric breeds rats for birds : REDBREASTS
13-across – Wrong note in port for seabird : HERRINGGULL
18-across – Bird in town centre going round to cinema providing animal shelter : WOODPIGEON
21-across – Kill two birds with one stone – that includes birds’ birthplace : NEST
22-across – Bird seen on street in pushchair : STROLLER
23-across – A bird has to mount it : TOMTIT
24-across – Wine for a bird : CANARY
25-across – Ruth or Rachel’s first bird : REGRET
All Down Clues and Answers:
1-down – Couple at work have sex : COPULATE
2-down – Space traveller revealed by start of oscillation in measuring instrument : METEOR
3-down – 25 of knitted jumper : TREEFROG
4-down – Girl’s three articles : ANTHEA
5-down – Bird may be hitch for hikers : SHRIKE
7-down – Hare-brained puss in pigpen : SCATTY
8-down – What Elvis sang about – and where, too : WOODENHEART
14-down – Mockingbird with lyre-shaped tail : RAILLERY
15-down – Outstanding feature of scenery – as well as mountain-top circled by bird : LANDMARK
16-down – It’s characteristic of a twitcher to follow the author of The Raven describing The Raven : POETIC
17-down – A beast of burden is the first to help : ASSIST
19-down – River in southern highlands floods : DROWNS
20-down – Spice Girls’ debut, having first met UN Assembly : NUTMEG
This crossword has in total 26 where 13 are across and 13 are down.