Date: 9/8/26 12:55 pm From: Stephen Broker via CTBirds <ctbirds...> Subject: [CT Birds] Some Comments on Breeding Codes and Safe Dates - Part II Safe Dates
The use of Safe Dates is explained nicely on the Atlas website. The description reads in part, “One of the difficulties with assigning breeding codes is that the behaviors the codes describe are sometimes used by birds away from their nesting sites. Migrating birds are particularly problematic because they often engage in breeding behaviors long before they get to their breeding grounds. When a species is known to not nest in a region, it is easy to recognize that they are not local breeders. But, when some individuals of a species breed in an area, while others migrate through en route to sites farther north, it becomes harder to know how some records should be treated.
“Like many breeding bird atlases, we attempted to address this problem by identifying ‘safe dates’ at the beginning of the project for each species known to breed in Connecticut. Safe dates give the period during which the occurrence of a bird means that there is a high likelihood that it is breeding near where it was seen, and that it is unlikely to be a migrant or a wandering nonbreeder. Safe dates do not identify the entire period in which breeding may occur, and records of birds engaged in breeding behaviors that confirm breeding were accepted even when outside this period. Breeding codes in the possible and probable categories, however, were generally not accepted unless they lay within these dates.”
This last statement carries particular meaning for me as it applies to peregrines and ravens. The Atlas published safe dates for Peregrine Falcon are from May 15 to August 1, yet I have seen and photographed peregrines with an egg in the nest as early as March 29, and almost always with eggs by April 10. Nest with eggs, that’s Confirmed breeding. Similarly, the published safe dates for Common Raven are from March 20 to July 20, yet I have confirmed that ravens have laid eggs in Connecticut beginning in late February. Nest with eggs, Confirmed breeding. The main point is, in properly reporting breeding evidence, it is important to observe safe dates in order to rule out birds in migration or birds paired up on their wintering grounds prior to breeding.
We’re now in September. The only birds with safe dates extending past late August are: Rock Pigeon (year-round nester, 1/1-12/31); Hermit Thrush (5/10-9/10); American Robin (5/1-9/1). Herons, woodpeckers, wrens, vireos, mockingbirds, starlings, sparrows, warblers, and grackles are all outside their safe dates now. If their behaviors now do not fall within the list of evidence confirming breeding, they should not now be assigned breeding codes. Again, it’s commendable to be familiar with breeding codes, but they should be used only when observing the appropriate safe dates - or if you have clear evidence of Confirmed breeding outside the safe dates.
Good birding!
Steve Broker
Cheshire
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