Cavity Nesters Recovery Program
Guadalupe Oak Grove Park Bluebird Trail Results

Results for the 2016 Season

Species Broods First Egg (Estimated)Eggs Hatched Fledged
Ash-throated Flycatcher (ATFL) 1 May 12 5 5 5
Tree Swallow (TREW) 2 May 9 11 10 10
Violet-Green Swallow (VGSW) 9 May 21 46 45 40
Western Bluebird (WEBL) 7 March 9 34 32 27
White-breasted Nuthatch (WBNU) 1 March 9 7 6 4
Totals 20 103 98 86

The weather in late 2015 and during the 2016 nesting season raised my hopes that our prolonged drought is ending. December 2015 experience significant rainfall, and periodic rains during the nesting season buoyed my hopes. Also, the nesting birds weren't exposed to prolonged extreme temperatures which increased the nestling's fledge rate.

On the plus side, Tree Swallows returned to nest in my boxes which they had not done since 2009. On the minus side, for the first time Oak Titmouse failed to nest in my boxes.


Results for the 2015 Season

Species Broods First Egg (Estimated)Eggs Hatched Fledged
Ash-throated Flycatcher (ATFL) 1 May 6 4 4 4
Oak Titmouse (OATI) 2 March 12 11 11 9
Violet-Green Swallow (VGSW) 10 May 1 44 42 27
Western Bluebird (WEBL) 4 March 30 20 17 14
White-breasted Nuthatch (WBNU) 1 March 15 5 5 5
Totals 18 84 79 59

Although the drought continued in 2015, December, February, and April rains provided improved results over the 2014 season. Basically we did not experience winter, and the weather remained cooler than normal into July. There was an unexpected surge in the nesting activity of Violet-Green Swallows while a nearby trail along a creek experienced no Violet-Green Swallow nesting activity for the second season. This creek stopped running both of the last two seasons.


Results for the 2014 Season

Species Broods First Egg (Estimated)Eggs Hatched Fledged
Ash-throated Flycatcher (ATFL) 1 May 22 4 3 3
Barn Owl (BANO) 1 March 19 3 0 0
Nutall's Woodpecker (NUWO) 1 April 18 1 0 0
Oak Titmouse (OATI) 3 March 16 16 15 8
Violet-Green Swallow (VGSW) 7 May 19 28 27 18
Western Bluebird (WEBL) 3 April 11 14 13 7
Totals 16 66 58 36

The 2014 season results provide insight into the impact the continuing drought is having on wildlife.


Results for the 2013 Season

Species Broods First Egg (Estimated)Eggs Hatched Fledged
Ash-throated Flycatcher (ATFL) 1 June 11 3 1 1
Barn Owl (BANO) 2 March 14 8 8 4
Nutall's Woodpecker (NUWO) 1 May 23 1 0 0
Oak Titmouse (OATI) 2 March 18 13 11 9
Violet-Green Swallow (VGSW) 9 May 13 40 39 30
White-breasted Nuthatch (WBNU) 1 March 28 7 7 7
Western Bluebird (WEBL) 6 April 10 28 26 18
Totals 22 106 98 75

The 2013 season results were better than the 2012 results. After an absence of three years, an Ash-throated Flycatcher nested in a box laying just three eggs of which only one hatched, but that hatchling fledged.


Results for the 2012 Season

Species Broods First Egg (Estimated)Eggs Hatched Fledged
Barn Owl (BANO) 1 March 13 2 0 0
Nutall's Woodpecker (NUWO) 2 April 12 6 0 0
Oak Titmouse (OATI) 2 March 26 5 5 5
Violet-Green Swallow (VGSW) 10 May 20 37 31 24
White-breasted Nuthatch (WBNU) 1 March 30 6 5 5
Western Bluebird (WEBL) 8 April 17 37 32 23
Totals 24 98 78 62

The 2012 season results were below expectations. Contributing to this were 2 Barn Owl eggs that were abandoned. One possible cause for the abandonment is that the female is dependant upon the male feeding her prey from the time she begins laying eggs through the time that the youngest owlet is twelve days old (is covered in down). If she isn't being fed enough prey, she will leave the nest to feed herself.


Results for the 2011 Season

Species Broods First Egg (Estimated)Eggs Hatched Fledged
Barn Owl (BANO) 2 March 15 11 4 4
Oak Titmouse (OATI) 2 March 25 15 15 7
Violet-Green Swallow (VGSW) 7 May 23 27 26 23
White-breasted Nuthatch (WBNU) 1 March 22 6 6 6
Western Bluebird (WEBL) 8 April 13 36 31 18
Totals 20 95 82 58

The 2011 season results rank among the poorer of the previous seasons. Key negative factors that contributed to the poor results were:

  1. The poaching of Western Bluebird eggs from one nest box.
  2. The theft of a nest box with up to 8 Oat Titmouse nestlings.
  3. The abandonment of eggs by a Barn Owl hen in one of the Park Department's Barn Owl boxes. This is the second season that this has occurred, and is likely due to the box's close proximity to the dog park. The noise from the park likely spooked the hen causing abandonment. The entrance hole to the box has since been plugged to avoid a recurrence.
  4. The late May and early June winds, and early June rain contributed to the loss of numerous nestings as the adults have a difficult time finding insects to feed themselves and their nestlings in such conditions.

Results for the 2010 Season

Species Broods First Egg (Estimated)Eggs Hatched Fledged
Barn Owl (BANO) 3 January 21 15 11 11
Oak Titmouse (OATI) 5 March 24 30 28 28
Violet-Green Swallow (VGSW) 4 May 17 20 20 17
White-breasted Nuthatch (WBNU) 1 March 30 5 5 5
Western Bluebird (WEBL) 9 April 16 42 40 29
Totals 23 112 104 90

Overall, the 2010 season results were good despite the cool and wet spring that we had. As is always the case, several anomalies were noted:

  1. No Ash-throated Flycatcher nests were even started, although they were seen in the park.
  2. All three of the Park Department's Barn Owl boxes had nesting Barn Owls. However, the box located next to the dog park was abandoned by the hen after having laid four eggs. The box's close proximity to the dog park and its activity likely caused the nest to be abandoned.

Results for the 2009 Season

Species Broods First Egg (Estimated)Eggs Hatched Fledged
Ash-throated Flycatcher (ATFL) 2 May 6 11 11 5
Oak Titmouse (OATI) 1 March 22 8 6 6
Tree Swallow (TRES) 1 May 11 5 4 4
Violet-Green Swallow (VGSW) 2 May 16 10 10 8
Western Bluebird (WEBL) 8 April 10 40 31 23
Totals 14 74 62 46

As was the case last year, several anomalies were noted:

  1. No White-breasted Nuthatch nests were completed.
  2. There was a marked decrease in the number of Oat Titmouse and Violet-green Swallow nests.
  3. The park experienced the first Tree Swallow fledgling from one of the trail's nest boxes.

Results for the 2008 Season

Species Broods First Egg (Estimated)Eggs Hatched Fledged
Ash-throated Flycatcher (ATFL) 2 May 9 10 9 8
Nuttall's Woodpecker (NUWO) 4 April 6 12 1 1
Oak Titmouse (OATI) 4 March 17 29 26 22
Violet-Green Swallow (VGSW) 6 May 17 24 22 15
Western Bluebird (WEBL) 7 April 15 36 34 18
Totals 24 111 92 64

The total number of fledglings for the 2008 season was only one more than that of the 2007 season despite having had more eggs, and hatchlings. It is assumed that the continuing lack of rainfall and periods of extremely hot weather are to blame.

Several anomalies from previous seasons were noted:

  1. No White-breasted Nuthatch nests were completed.
  2. The park experienced the first Nuttall's Woodpecker fledgling from one of the trail's nest boxes. Only one of twelve eggs in four broods hatched. Most of the eggs disappeared from the boxes.


Results for the 2007 Season

Species Broods First Egg (Estimated)Eggs Hatched Fledged
Ash-throated Flycatcher (ATFL) 2 May 17 10 10 9
Oak Titmouse (OATI) 2 March 23 15 15 15
Violet-Green Swallow (VGSW) 7 May 17 29 28 19
Western Bluebird (WEBL) 5 April 8 23 16 10
White-breasted Nuthatch (WBNU) 2 March 30 12 10 10
Totals 18 89 79 63

Given the number of available nest boxes in the park, the 2007 season was the statistically the worst that I have experienced since we assumed the trail in 2002. Most notable was the significant drop in the number of Oak Titmouse (OATI) fledglings-15 vs. last year's 38. Western Bluebird (WEBL) loses were high due to abandoned nests, unhatched eggs, and Hatched that didn't fledge. The early lack of rainfall and periods of hot weather may be to blame.


Results for the 2006 Season

Species Broods First Egg (Estimated)Eggs Hatched Fledged
Ash-throated Flycatcher (ATFL) 2 May 22 8 8 8
Oak Titmouse (OATI) 5 March 19 39 39 38
Violet-Green Swallow (VGSW) 9 May 18 36 29 25
Western Bluebird (WEBL) 5 April 14 25 25 24
White-breasted Nuthatch (WBNU) 1 March 27 6 5 5
Totals 22 114 106 100

Although there were losses (abandoned nests, unhatched eggs, and Hatched that didn't fledge), the 2006 season overall was better than last year (2005). Unfortunately, none of the Western Bluebird pairs produced second broods.


Results for the 2005 Season

Species Broods First Egg (Estimated)Eggs Hatched Fledged
Ash-throated Flycatcher 1 May 11 4 3 3
Oak Titmouse (OATI) 2 March 20 16 14 13
Violet-Green Swallow (VGSW) 6 May 24 27 22 22
Western Bluebird (WEBL) 5 April 7 22 13 8
White-breasted Nuthatch (WBNU) 3 March 14 19 18 13
Totals 17 88 70 59

The 2005 season experienced more tragedy than previous years.


Results for the 2004 Season

Species Broods First Egg (Estimated)Eggs Hatched Fledged
Ash-throated Flycatcher (ATFL) 1 May 1 5 5 5
Oak Titmouse (OATI) 2 March 14 17 16 15
Violet-Green Swallow (VGSW) 2 May 20 8 8 8
Western Bluebird (WEBL) 4 April 1 16 14 13
Western Screech Owl (WESO) 1 March 18 3 3 3
White-breasted Nuthatch (WBNU) 1 March 15 8 8 7
Totals 11 57 54 51

Last Modified On: September 3, 2016


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