I would like to know why they were even disturbing the birds the day after they were banded? Did they forget to do something on banding day...........seems kind of stressful for the birds. 
With the use of webcams, the birds get "disturbed" alot less than they used to and in the wild, they get disturbed frequently by other birds and predators if they can get close. The downside of the webcams is that they freak more, so get stressed more than they used to it seems (not enough data to say that for sure). Peregrines and peregrine chicks aren't fragile we just don't like to needlessly disturb them. Every nestsite and pair are different. Jules and Beau are spooky easy to disturb and they really really get disturbed and stressed. The Radisson birds generally not so much though the level of stress individual birds will put up with varies. Princess is more easily stressed off the eggs/chicks than Trey was or Madame. Together Madame and Trey would stay on the eggs pretty much no matter what happened. Interestingly, before webcams we used to get hit by birds pretty regularly by one or the other or both of a pair. Since webcams, it happens less, almost as though the birds aren't used to the disturbance so are still trying to figure out what the best response is to the "threat". In the old days, you had to check the chicks at laying (twice, sometimes three times to get an accurate incubation start date) and then when they were hatching in order to get as accurate and age for banding. After the first or second visit on the roof - say to check for a scrape and then after the first egg was laid, the pair knew who you were and where you were going to go - made it easy to determine a plan of attack (aka bombing run).
But back to your question RCF - 20 minutes or thereabouts to band and 5-10 minutes to spray the chicks and maybe another 10-20 minutes through the course of the season to adjust replace cameras, is not a problem if done efficiently and not at a time when the chicks could be negatively impacted by weather etc. Working with the birds mean one should keep the disturbance you can control to a reasonable minimum - I daresay if they decided there was a need to spray it was probably not something they were expecting the day before - it would have been so much easier for everyone if they could have sprayed them then. Fortunately, chicks tend to spit and hiss but generally settle down quickly after being disturbed - watch after we band the Radisson chicks next week, its a comforting sight when you work with them to see them get down to napping or eating or whatever relatively quickly after going back in the box - granted we try to facilitate that as much as we can. When they start to fly however, it seems as though a switch is flipped, like their first flights reveal possibilities and options that they just couldn't conceive of - dealing with fledglings is entirely different. A chick that 20 days before was acquiescent during banding will take chunks out of you when you retrieve them after going to ground at fledge time.
