[Length 7 in. Wingspan 13 in.]

This male Eastern Bluebird was photographed bringing food to its nestlings at a nestbox in the Texas Hill Country, USA. Photo taken with a Nikkor 300mm EDAF f4.0 lens on Kodachrome 200 film. (Date: June 1999)

[Length 7 in. Wingspan 13 in.]

This male Eastern Bluebird was photographed bringing food to its nestlings at a nestbox in the Texas Hill Country, USA. Photo taken with a Nikkor 300mm EDAF f4.0 lens on Kodachrome 200 film. (Date: June 1999)

[Length 7 in. Wingspan 13 in.]

This female Eastern Bluebird was photographed at Ingram, Texas, USA. Photo taken with a Nikkor EDAF 300 f4.0 lens on Kodachrome 200 film. (Date: June 1999)

[Length 7 in. Wingspan 13 in.]

This male Eastern Bluebird was photographed at the Falfurrias rest area on Route 281, Falfurias, Texas, USA. Photo taken with a AF-S VR Zoom-Nikkor 80-400mm f/4.5-5.6G IF-ED lens on a Nikon D7100 camera. (Date: October 25, 2014)

[Length 7 in. Wingspan 13 in.]

This male Eastern Bluebird was photographed at the Falfurrias rest area on Route 281, Falfurias, Texas, USA. Photo taken with a AF-S VR Zoom-Nikkor 80-400mm f/4.5-5.6G IF-ED lens on a Nikon D7100 camera. (Date: October 25, 2014)

[Length 7.25 in. Wingspan 14 in.]

The sky-blue coloring of male Bluebirds certainly makes them one of the most beautiful of the New World thrushes. Bluebirds declined in numbers for several decades due to several factors. One is that European Starlings and House Sparrows competed aggressively with them for nesting sites. Another is that Bluebirds require open spaces, which are disappearing as land is developed for housing and business uses. However, the concerted efforts of people to put up specially-designed nest boxes specifically sized for Bluebirds (and slightly too small for Starlings) have resulted in promising increases in their numbers. This male Mountain Bluebird was photographed at Robert Lee, Texas, USA. Photo taken with a AF-S VR Nikkor 300mm f/2.8G IF-ED lens + Nikkor TC14E II 1.4x Teleconverter (EFL=630mm) on a Nikon D200 camera. (Date: January 4, 2009)

[Length 7.25 in. Wingspan 14 in.]

This male Mountain Bluebird was photographed at Robert Lee, Texas, USA. Photo taken with a AF-S VR Nikkor 300mm f/2.8G IF-ED lens + Nikkor TC14E II 1.4x Teleconverter (EFL=630mm) on a Nikon D200 camera. (Date: January 3, 2009)

[Length 7.25 in. Wingspan 14 in.]

This female Mountain Bluebird was photographed at Robert Lee, Texas, USA. Photo taken with a AF-S VR Nikkor 300mm f/2.8G IF-ED lens + Nikkor TC14E II 1.4x Teleconverter (EFL=630mm) on a Nikon D200 camera. (Date: January 4, 2009)