Date: 7/11/20 7:46 am From: Bird observations from western New York <geneseebirds-l...> Subject: Re: [GeneseeBirds-L] Common Nighthawk - Buffalo
I have heard the theory about crows taking advantage of nighthawks nesting on roofs in the cities and I think there could well be something to that. I checked Birds of the World at the Cornell Lab but other than domestic cats, there are few other predators on nighthawks that have been documented. However, they also indicated that ravens, crows, gulls, kestrels, owls, coyotes, foxes, and snakes were likely predators as well. And, that ground-nesters like Nighthawks, are especially vulnerable to skunks, opossums, and raccoons.
However, I have never heard the theory mentioned by Gerry and attributed to Bob Brock, of plastic bags making it easier for crows to forage through our garbage. This behavior, however, has been documented and it makes sense that it could have helped to swell the numbers of crows in urban locations. While it is certainly true that crows spread into urban areas from rural areas, which they never really left, and that this was likely due to a good food supply as well as fewer predators, I am not so sure that crows are now leaving cities in favor of rural sites. According to birders, there are still many crows in the cities. Overall, numbers seem lower than say, 25 years ago, but this could well be due to West Nile Virus, of which the American Crow is particularly susceptible.
Coincident with an increase in crows in urban areas, flat roof construction on buildings changed also. Instead of gravel roofs, which the nighthawks preferred for their nests, rubber roofs are now used. The gravel prevented the eggs from rolling and the rubber may allow the roofs to get hotter than gravel roofs, both of which could be detrimental to nesting success. In addition the solid color of rubber roofs may reduce camouflage of the eggs, allowing for easier detection by predators. Placing gravel pads on the corners of flat rubber roofs may help nighthawks.
From: <geneseebirds-l-bounces...> [mailto:<geneseebirds-l-bounces...>] On Behalf Of Bird observations from western New York
Sent: Saturday, July 11, 2020 9:49 AM
Subject: Re: [GeneseeBirds-L] Common Nighthawk - Buffalo
You have to be an elder citizen today to recall the days when nighthawks flew over our cities, especially noticeable at nighttime baseball games. To me it was just as interesting watching them catch bugs around the lights as watching Musial, Dusak, Roe, Crabtree, Shoendienst and others play for the RedWings.
Some years ago Bob Brock shared with me his understanding why we lost our city nighthawks. It was due, he claimed, to our change in garbage collection. At the time he offered this idea, we had begun leaving garbage for collection in plastic sacks and these had attracted crows to the city for easy scavenging. Before that crows had been rural birds rarely occurring in urban areas except in a few nighttime roosts. The problem for the nighthawks was that the newly arrived crows also raided the nighthawks' open rooftop nests for eggs and young. They completely extirpated the species from our cities.
I agree completely with Bob's analysis. But now times have again changed and we no longer have open garbage sacks. They are contained in solid carriers. Those can be raided by raccoons but not by crows and, as a result, the crows are retreating to their old habitats. It would be wonderful if nighthawks would return to those open roofs with their major predator in retreat.
From: <geneseebirds-l-bounces...> <geneseebirds-l-bounces...> on behalf of Bird observations from western New York <geneseebirds-l...>
Sent: Friday, July 10, 2020 11:25 PM
To: <geneseebirds-googlegroup...>; <geneseebirds-l...>; <NYSBIRDS-L...>; David Suggs
Subject: [GeneseeBirds-L] Common Nighthawk - Buffalo
While leaving Wegmans (Amherst St - Blackrock) this evening just after 10:00 pm, I had a Common Nighthawk calling. There may have been an additional bird or two, but I could not see the birds due to the floodlights in the lot. A nice and unexpected treat!