Using the GRASP rules, these are created as 'engineer' units which allows them to modify areas of terrain, making them difficult and often dangerous to traverse.
The profile above by Bartelski shows a medium grey finish which I think matches the picture below.
Source Ivan Gogin
There is another source showing a much darker finish:
|Original Source Not Known|
There is also the following picture which shows a model with a two-tone grey finish and armour cladding:
Source 1/100 paper model
Since these ships served over a longish period, with the last one was decommissioned in 1970, I guess there was plenty of opportunity for variation over theatre of service and time. As for their fate - to quote Gogin (2009-16)
'Jaskółka and Czapla were sunk by German aircraft 14/9/1939 at Jastran. Mewa and Rybitwa were sunk 3/9/1939 by German aircraft at Hel naval base. They were salvaged by Germans in November, 1939 and renamed Putzig and Rixhoft. In 1940 they were converted to torpedo retrievers and renamed TFA9 and TFA8 respectively. Czajka was captured by German troops at Westerplatte and commissioned by Kriegsmarine as TFA11. In May, 1945 TFA8, 9 and 11 surrendered at Kiel and in 1946 returned to Poland. Żuraw was captured by German troops in October, 1939 and commissioned by Kriegsmarine as Oxhoft. After war she was also returned to Poland.' Ivan Gogin