Guadalupe Oak Grove Park Bluebird Trail Results
For the years of 2002 through 2017 the birds nesting in my nest boxes in the park have laid 302 clutches totaling 1,444 eggs from which 1,024 nestlings have fledged.
Results for the 2017 Season | |||||
| Species | Broods | First Egg (Estimated) | Eggs | Hatched | Fledged |
| Oak Titmouse (OATI) | 1 | March 20 | 7 | 7 | 7 |
| Tree Swallow (TREW) | 5 | April 27 | 25 | 25 | 22 |
| Violet-Green Swallow (VGSW) | 12 | May 5 | 57 | 56 | 40 |
| Western Bluebird (WEBL) | 8 | April 9 | 37 | 33 | 21 |
| White-breasted Nuthatch (WBNU) | 1 | March 22 | 7 | 7 | 7 |
| Totals | 27 | 133 | 128 | 97 | |
Despite above normal rainfall and temperatures hitting 109 in mid-June, it was a good season with 97 nestlings having fledged.
A fire in the park on June 12th was the probable cause of the loss of 5 Violet-green nestlings due to smoke inhalation.
Once again, Ash-throated Flycatchers, although visible in the park, did not nest in any of my nest boxes.
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 experienced 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.
- A Barn Owl hen laid three eggs, and abandoned them before they hatched. The hen is dependant upon the male to feed her for a period of time the includes the time she is incubating her eggs, and if she isn't being fed enough, she will abandon her eggs in order to feed herself. Due to the drought, the quanity of prey that the owls feed on was down (pocket gophers, mice, voles, etc.).
- Violet-Green Swallow numbers were down across the board. The swallows feed on flying insects which were fewer in number due to the lack of moisture.
- Western Bluebird numbers were more than halved. The bluebird feed on insects which were fewer in number due to the lack of moisture.
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:
- The poaching of Western Bluebird eggs from one nest box.
- The theft of a nest box with up to 8 Oat Titmouse nestlings.
- 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.
- 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:
- No Ash-throated Flycatcher nests were even started, although they were seen in the park.
- 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:
- No White-breasted Nuthatch nests were completed.
- There was a marked decrease in the number of Oat Titmouse and Violet-green Swallow nests.
- 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:
- No White-breasted Nuthatch nests were completed.
- 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.
- One Bluebird clutch of three eggs was destroyed, and House Wrens are suspect.
- One Bluebird clutch of five eggs was abandoned. This can happen if something happens to the female.
- All five Bluebird nestlings in one box were found dead, and House Sparrows are suspect.
- A Violet-Green Swallow nest with a clutch of five eggs was abandoned after the nest box was vandalized.
- Six 1-2 week old White-breasted Nuthatch nestlings disappeared from the nest box. A snake is suspect in their disappearance.
- The female Western Screech Owl that was occupying a Flicker nest box was displaced by European Starlings.
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: November 20, 2017