Fostering House Wren Orphans

House Wren (Immature)

House Wren (Immature)

Maintaining and monitoring nestboxes for Eastern Bluebirds, Tree Swallows, House Wrens, Carolina Chickadees, Tufted Titmice and other species sometimes provides an opportunity to offer a foster home for orphaned nestlings. I, and other bluebirders, are on a list at the Ohio Wildlife Center so when nestbox orphans are presented, the center contacts us to see if there are any active nests with potential foster parents that can accept orphans and give them a chance at fledging into the outside world. In the meantime, volunteers at the Wildlife Center fill the role of foster parents by hand feeding any orphans as feathered foster parents are sought.

Six orphaned House Wrens were presented to the center and Kristi Krumlauf sent an email to three of us on August 7, 2019. Attached to the email was a photo image of two nestlings in hand that appeared to be around eight days old. My question at the time was, do I have any wren nests that could accept the orphaned wrens?

Delaware State Park is home to 166 nestboxes. My data book is divided into the following five sections: notes, numbered box index, maps, trail data sheets, and box data sheets.

Trail data sheets have 25 time-lines, one time-line for each nestbox, from March 15 to September 15 with every month divided into two 15-day columns. All time-lines are color coded with bluebird data highlighted in yellow, wren data is red, data for Tree Swallows is green, etc. As I examined seven pages of trail data, I found 27 boxes with red time-lines that had nestlings during my last monitoring visit on August 6.

I then checked each box’s data calendar that includes a square for every day of the year with 31 squares in a row for every month of the year. Of course, some squares are blacked out at the end of some rows to adjust for months with 28-30 days. A box data calendar makes it possible for extrapolation to calculate first egg dates and fledging dates and the ages of nestlings on specific dates.

Among the 27 nests listed from the trail data calendars, I was looking for wren families whose nestlings were eight days old. I found that three families had fledged, leaving 24 with young. The wren orphans became lucky after four of the 24 active nests were found to have nestlings with ages matching the age of the orphans.

I contacted the Wildlife Center and arranged to pick up the orphans at the center’s hospital at 2661 Billingsley Road in Columbus. From my garage, I retrieved my plastic coffee can that I use to transport orphaned or injured birds. It has a bed of white pine shavings, and a paper towel on top helps to form a temporary nest cup for wrens. The can’s plastic lid has eight holes drilled through it to allow proper ventilation.

Upon my arrival, the human team of foster parents fed the orphans one last time before we placed them in their coffee can transportation capsule, and off we went for the 20-mile drive to Delaware State Park north of Delaware.

This wasn’t my first time transporting avian orphans in my car, so I was not surprised to hear no peeping from the coffee can until I drove around numerous roundabouts. As my car turned the corners, the centrifugal forces caused concern in my juvenile passengers. At least one wren would peep during each turn. Maybe it was their way of saying that they were healthy enough to express themselves, and I was alert enough to smile.

Once I arrived at the park, the mission became routine. I had planned to add two orphans to each of three nests. A fourth nest had been excluded because it held five nestlings and I did not want to overload a family.

Of the three pairs of orphans, I added two pairs to families of three, and joined the third pair to a family of four nestlings. It only took twenty minutes to deliver all the new siblings to their host nests.

House Wren Nestlings

A typical brood of House Wren nestlings.

When adding an orphan to its host family, I don’t disturb anyone. I gently place the orphans on the exposed rim of the nest cup and let the nestlings work things out from that point. If I have the time, I will try to watch from my car to see if a parent arrives to feed, and observe its behavior once it leaves the box. I will always check the family the day after fostering to make sure things are going well. I think that parent birds can’t count, but it could be that they are programmed to welcome young of their own species.

By the time I had added the orphans to their new homes, I had become concerned since no adult wrens showed up to protest my presence. My present explanation is that the adults did not see me because they were deep into the brush seeking prey for food. I believe the summer insect populations were below normal levels due to extremely wet weather conditions. The required sizes of hunting territories are becoming larger and less supportive.

As I checked the nests the next day, I found all of the nestlings snuggled together in their nest cups. They all looked content, a sure sign that their biological and foster parents were doing a good job, and the fostered nestlings had been universally accepted.

I followed my regular monitoring schedule on August 15 and 16 to find that one family had fledged on the 15th, while another family remained in their box. If wren nestlings are within several days of fledging, a monitor must only peak in the nest while keeping the box’s door closed enough to prevent pre-fledging.

By the next day, the hesitant family from the previous day had fledged, and at the far northern end of the park, the last family had fledged while leaving a dead nestling behind. Was the deceased wren a member of the host family, or was it one of the orphans? I have no way of knowing, but what I do know is that nestlings can choke on food items and there are other natural causes. I saw no signs to explain its failure to fledge.

The transplanting of the August 8 wren orphans was a success. Unfortunately, a later family of four wren orphans presented to the Wildlife Center on August 22 and were too young to foster with any of the park’s four active nests at the time. If fostered wrens are several days younger than their host family, then when the host family flies from the nest, the parents forget, or ignore, the fostered nestlings left behind, and they end up dying.

Do your best to help our avian friends, and when possible, foster on.