Announcing an Anna's Annual Arrivals Analysis
Combined Data from 2003-2013
Temporal data for 15 different Anna's hummingbird nests constructed in the same Tasmanian tree fern in San Diego, CA.

     Nest- building Egg- laying Egg- hatching Chick- fledging
Year Started Finished First Egg Second Egg First Egg Second Egg First Chick Second Chick
2003 Mar 04 Mar 08 not observed not observed ~Mar 30 ~Mar 30 Apr 16 Apr 19
2004 Feb 24 Feb 28 Feb 29 After Mar 06 Mar 17 +Mar 18 dead Apr 09 -
2005a Feb 24 Feb 28 Mar 04 Mar 06 ~Mar 22 ~Mar 22 Apr 14 Apr 14
2005b May 22 May 25 May 25 May 27 Jun 10 Jun 11 Jul 03 Jul 03
2005c Dec 22 Abandoned - - - - - -
2006 Feb 26 Mar 01 Mar 07 Mar 10 Mar 25 Mar 26 Apr 19 ^see note
2007 Mar 04 Mar 08 Mar 09 Mar 11 not observed not observed Apr 17 Apr 17
2008 Mar 08 Mar 12 Mar 14 Mar 16 Mar 31 Apr 01 *Nest gone on Apr 08
2009 Apr 23 Apr 27 Apr 29 May 01 *Eggs gone on May 05 - -
2010 Dec 30 Jan 13 Jan 16 Jan 19 Feb 3 Feb 6 Feb 25 Dead at birth
2011 May 12 May 17 May 18 May 20 Jun 3 Jun 5 Jun 24 Jun 24
2012 Apr 14 Apr 17 Apr 18 Apr 20 Apr 20 Hole in nest - -
2013a ~Jan 8 Jan 13 Jan 26 Jan 28 ~Feb 12 ~Feb 14 Mar 5 Mar 5
2013b ~Mar 16 Mar 21 Mar 21 Mar 24 @Eggs gone on April 6 - -

+Mar 18 dead, 2004. The mother hummingbird appeared to break open the egg of the dead chick with her beak.
^Apr 08, 2006. Chick was found on the ground under nest, placed back in the nest, found on the ground again, and taken to the local humane society.
*2008 nest and chicks and *2009 eggs were presumably preyed upon by ravens or hawks, which are frequently observed hunting in the neighborhood.
@We discovered the nest unattended with neither eggs nor chicks on April 6, 2013. Presumably, a raven took them.


Timing of Anna's Hummingbird Nesting Events by Year (2003-2009)
Time in days until nest completed, eggs laid, eggs hatched, and chicks fledged.

     Nest- building Egg- laying Egg- hatching Chick- fledging
Year Started Finished First Egg Second Egg First Egg Second Egg First Chick Second Chick
2003 Day 0 Day 4 - - ~Day 26 ~Day 26 Day 42 Day 45
2004 Day 0 Day 4 Day 5 ~Day 11 Day 22 Day 23 (died) Day 44 -
2005a Day 0 Day 4 Day 9 Day 11 ~Day 26 ~Day 26 Day 48 Day 48
2005b Day 0 Day 3 Day 3 Day 5 Day 19 Day 20 Day 42 Day 42
2005c Day 0 Abandoned - - - - - -
2006 Day 0 Day 3 Day 9 Day 12 Day 27 Day 28 Day 52 -
2007 Day 0 Day 4 Day 5 Day 7 - - Day 44 Day 44
2008 Day 0 Day 4 Day 6 Day 8 Day 23 Day 24 - -
2009 Day 0 Day 4 Day 6 Day 8 - - - -
2010 Day 0 Day 10 Day 17 Day 20 Day 36 Day 36 Day 58 -
2011 Day 0 Day 5 Day 6 Day 8 Day 22 Day 24 Day 43 Day 43
2012 Day 0 Day 5 Day 5 Day 7 - - - -
2013a Day 0 Day 5 Day 18 Day 20 Day 37 Day 37 Day 56 Day 56
2013b Day 0 Day 5 Day 7 - - - - -
Totals: n=14 n=13 n=12 n=11 n=9 n=9 n=9 n=6
Averages: - ~5 Days ~8 Days ~11 Days ~26 Days ~27 Days ~48 Days ~46 Days

Based on the data in the 2 tables shown above, for 13 different Anna's hummingbird nests built between 2003 and 2013 in a single Tasmanian tree fern in San Diego, CA, the average time to build a nest is ~5 days. The average time for the first and second eggs to be laid is ~5 and 8 days, respectively. The average time for both eggs to hatch is ~26-27 days, and the average time for both chicks to fledge the nest is ~46-48 days from the onset of nest-building. Generally, it takes about 3 weeks for the eggs to hatch and another 3 weeks for the chicks to fledge. Note that for the 3 nests built during the coldest months (2005a, 2010, and 2013a), the total time to fledge was about 10 days longer than the average. However, most of this extra time consisted of a long lag between the time of nest building and laying the eggs. Once the eggs were laid, development proceeded fairly normally, despite the cold.



Torrey Pines Peregrine Falcons.


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