Uncommon summer visitor, numbers having seriously declined in recent years.

Nationally Cuckoos have declined by 65% since the early 1980s. They are dependent on their preferred host species, such as Dunnock (Prunella modularis) and Meadow Pipit (Anthus pratensis), and as a result their population fluctuates accordingly. In 1967 a pair of Dunnocks in a Fairview Road garden died of exhaustion feeding a recently fledged Cuckoo (which also succumbed later). A Cuckoo egg was found in a Dunnocks nest at Astonbury Wood on 29 May 1977 and, on 25 June 1978 a full grown flying juvenile was seen being fed by a Dunnock at Astonbury.

The earliest record of one at Stevenage is 22 March 1894, the 1894 Bird Report noted that this information had come from a newspaper. It used to be common practice for people to write to newspapers claiming the first date of hearing a Cuckoo for the year.

The earliest (verified) spring arrival date at Stevenage is 1 April 1972 at Astonbury, the latest departure date is 1 August 1972 at Watery Grove. The most seen together are seven seen on electricity wires at Watery Grove on 10 May 1973, and up to six were seen on the same wires in May 1975.

The 1973 Breeding Atlas confirmed breeding from one tetrad and probable breeding from the other 10 tetrads covering Stevenage, the 1992 Atlas confirmed breeding from four tetrads and probable breeding from the other seven tetrads covering Stevenage. The 2012 Atlas only recorded possible breeding from four tetrads. 

The Common Bird Census at Watery Grove recorded one breeding territory being held from 1972 to 1996, with the exception of 1973, 1976, 1979, 1990, 1991 and 1995, when along with 1997 and 1998, their presence only during the breeding season was recorded. Three were calling at Watery Grove on 14 May 2005.

Since 2012 records have come from Norton Green Tip, with the most recent record of one on 1 May 2020. Other records are: one recorded from Monkswood Way on 3 May 2020 and one seen flying over Stanley Road on 14 June 2022.

They were formally recorded from: Aston (last record 3 May 1995); Astonbury (last record 14 May 2000); Aston End (last record 17 May 1999); Box Wood (last record 23 April 1988); Fairlands Valley Lakes (last record 3 April 2001); Pryors Wood (last record 23 April 2011); Wellfield Wood (last record 3 April 1973); Whomerley/Monks Wood (from where their reduced numbers was commented on in 1969).