Swallow Study

Tree Swallow Nests in the Petaluma Public Wetlands

The swallows nesting in boxes at Shollenberger/Alman Marsh/Ellis Creek are Tree Swallows, Tachycineta bicolor.

Swallow Nesting Study

Cleaning nest box

On 5 April 2007, I began monitoring 20 swallow boxes build by PWA docent Andy LaCasse. The boxes, located in Shollenberger and Alman Marsh, are monitored using the protocols of a study called Golondrinas de las Americas, which employs naturalists ranging from Alaska to Argentina. In late 2009, five of these boxes were relocated and six newly constructed were erected in Ellis Creek. In April of 2011, two more houses were added to those in Ellis Creek.

PWA’s goals in monitoring these houses are manifold:

  • Determine the usefulness of our nest boxes
  • Learn about the natural history and nesting results
  • Teach others about the importance of our nest boxes
  • Ensure nest boxes are not used by nonnative birds
  • Provide habitat for Tree Swallows and Blue Birds
  • Monitor, clean, and maintain the boxes to improve the odds of chicks fledging
  • Contribute to the Golondrinas study
  • Share data with PRBO Conservation Science and other interested parties

Ten years have now passed since I started monitoring the Tree Swallows in Shollenberger Park and, since 2014, Ellis Creek Oxidation Ponds and Tolay Lake Regional Park. There are 57 houses in total and the results from each territory differ with Shollenberger not doing as well as the other areas. Why this is the case is not known. However, in 2017, I intend to move a few houses out of Shollenberger to Ellis Creek where the houses are spread further apart. Hopefully, this will improve the mortality rate at the latter.
Still to do in 2016 is the task of cleaning the houses in preparation for 2017. Most are preliminarily cleaned at the end of their nesting cycle in late July – early August. But some need a more thorough cleaning or house replacement. This is done in October – November once the days are cooler and the tick population subsides.
If you are interested in getting involved in any capacity, please let me know. Efforts to improve the Tree Swallow / Bluebird mortality rate in addition to being extremely interesting are also challenging and rewarding especially when one’s efforts culminate in good results.

Details on how these nests are monitored and any questions concerning the below data can be obtained by contacting me, Len Nelson, at lennelsn@comcast.net.

2007                    eggs    _    chicks      _   fledge __     mortality  _     houses

1st nesting              99               73                 49            24 (32.9%)
2nd nesting             59               40                 21            19 (47.5%)
Totals                    158             113                 70            43 (38.1%)            20

2008

1st nesting             89                 74                41            33 (44.6%)
2nd nesting            34                 32                18            14 (43.8%)
Totals                   123               106                59            47 (44.3%)            20

2009

1st nesting           105                  96               50            46 (47.9%)
2nd nesting            70                  55               20            35 (63.6%)
Totals                   175                151               70            81 (53.6%)            20

2010

1st nesting           189                 171              151          20 (11.7%)
2nd nesting          132                 108    _          71           37 (34.3%)
Totals                  321                 279              222          57 (20.4%)             36

2011

1st nesting           189                 127             113           14 (11.0%)
2nd nesting          162                 134             114           20 (14.9%)
Totals                  351                 261             227           34 (13.0%)             38

2012

1st nesting           164                 149             131           18 (12.1%)
2nd nesting            47                   53               37           16 (30.2%)
Totals                   211                 202             168           34 (16.8%)             28

2013
1st nesting           145                  131              111           20  (15.3%)
2nd nesting           101                   90                49           41 (45.6%)
Totals                   245                  221              160           61 (27.6%)            28

2014
1st nesting           156                 133               109          24  (18.0%)
2nd nesting            23                   21                  8          13  (61.9%)
Totals                  179                  154               117         37 (24.0%)              28

2015
1st nesting           144                109                 84          25  (22.9%)
2nd nesting          117                  99                  39          60  (60.6%)
Totals                  261                 208               123           85  (40.9%)           28

2016
1st nesting          145                  132               82            50  (37.9%)
2nd nesting         103                    89                63            26  (29.2%)
Totals                 248                   221              145            76  (34.4%)           28

Bluebirds (BB) and Tree Swallow (TS) results: In 2016, 9 of the 145 chicks (6%) that fledged were BB but only 1 of the 28 houses (4%) were occupied by BB.

10  Year Cumulative for Shollenberger – Ellis Creek:
1st nesting         1,321                1,111               846           265  (23.9%)
2nd nesting           754                   651               376           275  (42.2%)
Totals                2,075                 1,762            1,222           540  (30.6%)       28

 

For the last 3 years, I have also been monitoring and maintaining on a regular basis bird  houses at the Ellis Creek Oxidation Ponds (10 houses) and at Tolay Lake Regional Park  (17 houses). 

Here are the results for these 2 locations:

2014  – Ellis Creek Oxidation Ponds:

                                 eggs                 chicks                  fledge            mortality      houses

1st nesting                63                        55                       51                5 (9.10%)
2nd nesting               28                        23                       21                2 (8.7%)
Totals                        91                       78                       72                 7  (9.0%)       10

2015  – Ellis Creek Oxidation Ponds:

1st nesting                62                        51                       50                1 (2.0%)
2nd nesting               29                        27                       20                7 (25.9%)
Totals                       91                        78                       70                8  (10.3%)       10

2016  – Ellis Creek Oxidation Ponds:

1st nesting                51                        47                       41                6 (12.8.0%)
2nd nesting               33                        26                       24                2 (7.7%)
Totals                       84                        73                       65                8  (11.0%)       10

Bluebirds (BB) and Tree Swallow (TS) results: In 2016, no Bluebirds occupied any of the 10 houses there.

2  Year Cumulative (EC-OXI)
1st nesting              171                       154                    142                12  (7.87%)
2nd nesting              90                          76                     65                11  (14.5%)
Totals                    261                         230                    207              23  (10.0%)        10

 

2014  – Tolay Lake Regional Park:

                                 eggs                 chicks                  fledge            mortality      houses

1st nesting                76                        64                       55                   9  (14.1%)
2nd nesting               30                        28                       18                  10  (35.7%)
Totals                     106                        92                       73                   19 (20.7%)       16

2015  – Tolay Lake Regional Park:

1st nesting                75                        54                       47                   7  (13.0%)
2nd nesting                58                        41                       25                 16  (39.0%)
Totals                       133                        95                       72                 23 (24.2%)       17

2016  – Tolay Lake Regional Park:

1st nesting                84                        63                       59                   4  (6.3%)
2nd nesting               40                        32                       31                    1  (3.10%)
Totals                      124                        95                       90                   5 (5.3)             17

Bluebirds (BB) and Tree Swallow (TS) results:  In 2016, 12 of the 90 chicks (13%) that fledged were BB and 4 of the 17 houses (23%) were occupied by BB.

3  Year Cumulative (Tolay Lake Regional Park)
1st nesting              235                       181                    161                  20   (11.0%)
2nd nesting             128                      101                      74                   27  (26.7%)
Totals                     363                      282                    235                  47  (16.7%)      17

The Tree Swallow – Bluebird houses are visited on a 7-10 day basis.  Those that are easier to access (SP-EC) can get more frequent visits if observed conditions warrant it and if time is available.  In 2016, diatomaceous earth was used whenever any mite condition was suspected and even after eggs were laid and before they hatched as a preventative measure. This action is believed to have had the desired result.  In 2017, the intention is to use it in all cases after eggs are laid and before they hatch.

Please let me know should you have any questions.

Len Nelson

PWA Shollenberger Docent

lennelsn@comcast.net

 

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