Mystery Disappearance of House Sparrows

Jean Iron and Ron Pittaway

 A dozen or so House Sparrows have roosted year round for many years in the tangled English Ivy growing against the house wall under the car port at 9 Lichen Place in Toronto. Figure 1. Here they are sheltered from cold weather, wind, rain and snow. The musical chirping of the roosting flock was a welcome sound especially in the worst weather. In the mid 1990s, we put up a nest box in the ivy where pairs have nested for about 15 years, and the sparrows are regulars at the birdfeeders. This winter we noticed that fewer and fewer House Sparrows went to roost in the ivy in late afternoon and flew out in early morning, until there were none. Since it was a cold winter, we thought they moved to another roost in one of the dense evergreens in the neighbourhood.

Figure 1. English Ivy under carport at 9 Lichen Place where House Sparrows roosted at night.

Then on 25 March 2011, we had a clue to the mystery of the disappearance of the House Sparrows. Surprisingly in mid afternoon on this cold sunny day, we saw an Eastern Screech-Owl perched on the shed close to the ivy where the sparrows had roosted and stared at the ivy. Next afternoon, the screech-owl again perched in the same spot on the shed, staring at the ivy. Figure 2.

Figure 2. Eastern Screech-Owl on shed under carport in the afternoon of 25 March 2011.

Hunting on bright sunny days is not normal behaviour for screech-owls. It was probably stressed for food. The recent weather had been cold and the small mammal population seemed to be low in Brookbanks Ravine this winter. We believe the screech-owl had been preying on the sparrows at their night roost in the ivy. On these cold days in March the owl was very hungry and returned to a place that earlier had sparrows. In the leaves on the ground under the ivy we found House Sparrow feathers supporting the conclusion that the screech-owl caused the disappearance of the sparrows. Figure 3. 

Figure 3. Two of the feathers found under the ivy where the sparrows roosted.

Figure 4. Male House Sparrow checked out the nest box on 17 April 2011

This Eastern Screech-Owl was probably a resident that breeds in Brookbanks Ravine, but we don’t know whether it survived the winter. On 17 April 2011, a male House Sparrow was checking out the nest box in the ivy. Figure 4.Though it hasn’t yet taken up residence, we look forward to the return of the House Sparrows.

First published in Toronto Ornithological Club Newsletter No. 215. May 2011.