Last month I noted that several pairs of barn swallows (Hirundo rustica) were checking out the ledge on the overhang of our back deck as possible nesting sites. The swallows were hovering around the potential spots and then landing to sit and get the feel of different areas where nests could be built. They had plenty of locations to choose from because the overhang is about thirty feet long and all prime nesting space. I was excited that the barn swallows would once again raise their broods outside my kitchen window.
After several days only one barn swallow pair remained on the deck and they chose a building spot directly above a remote temperature sensor – all that expanse of bare overhand and these two birds elected to construct their nest on the sensor – the ONE location I did not want a nest. The battle of wills began! First I shooed the birds to a different area, then I moved the sensor. . . no matter what I did to gently discourage a nest over the temperature sensor, the swallows were determined. After several days I gave in first. The swallows can have the sensor!! For the last three or four days the swallow pair has been building their nest directly over my sensor.
The male and female build the nest together out of mud pellets. Usually the swallows work in the morning and then leave for the remainder of the day while the new, wet portion of their handiwork dries. Barn swallows first construct a platform for the nest out of mud balls mixed with grass stems for added strength. Then they build up sides to form a circular cup (no wall to build against) or semicircular half cup (if there is a wall to build against) about three inches across at the rim and two inches deep. The swallow pair makes over 1,000 trips to bring mud pellets to create the nest. Finally the completed cup will be lined with grass and feathers. This swallow pair was actually wise to incorporate the temperature sensor into their nest because it adds more stability.
I think the nest is about finished and the pair should lay their eggs within the next few days. Two nights ago the male and female spent the night on the ledge with their nest for the first time. Neither was in or on the nest but they stayed on the ledge next to the nest throughout the night. Leonard and I continue our regular activities in the kitchen and on the deck. The swallows are comfortable with our presence.
These pictures were taken on my back deck (Lookout CA) over three days. The fresh mud from the current day’s building activities is easily distinguished from the dried mud from the previous day. Note the horsehair incorporated into the nest (picture of the nest alone). Many species of birds use the hair from our horses’ tails in building their nests. In another picture the swallow is wrapping a long stem with a leaf at the end into the fabric of the nest.
In a few days there should be barn swallow eggs to share in a post – then chicks. I am, in spite of the mild test of my will, delighted to have a barn swallow nest to easily observe.