References
Kessen, A. E., & Zink, R. M. (n.d.). Birds. Retrieved March 5, 2017, from http://www.biologyreference.com/Ar-Bi/Bird.html
Levine, J. S., & Miller, K. R. (2008). Chordates. In Prentice hall biology. Retrieved March 5, 2017, from http://www.jayreimer.com/TEXTBOOK/iText/products/0-13-115516-4/ch30/ch30_s1_1.html
Lima-de-Faria (1)(2), A. (2011, December 5). The symmetry of birds emerges as the expression of an uninterrupted atomic order. Retrieved March 5, 2017, from https://link.springer.com/chapter/10.1007%2F978-3-642-25301-0_9
Macklin, M. (2015, May 29). DDT, the California condor, and a decades-long battle with a banned pesticide. Retrieved March 5, 2017, from http://www.onegreenplanet.org/environment/ddt-the-california-condor-and-a-decades-long-battle-with-a-banned-pesticide/
Switek, B. (2011, August 26). An ode to Archaeopteryx. Retrieved March 5, 2017, from http://www.smithsonianmag.com/science-nature/an-ode-to-archaeopteryx-63181085/
Thomas, A. L. (1997). On the Tails of Birds. BioScience, 47(4), 215-225. doi:10.2307/1313075
Thompson, M., & Russell, M. (2014). All about feathers. Retrieved March 5, 2017, from https://academy.allaboutbirds.org/all-about-feathers/
Yeoman, B. (2016, April 13). Why the passenger pigeon went extinct. Retrieved March 5, 2017, from http://www.audubon.org/magazine/may-june-2014/why-passenger-pigeon-went-extinct
Kessen, A. E., & Zink, R. M. (n.d.). Birds. Retrieved March 5, 2017, from http://www.biologyreference.com/Ar-Bi/Bird.html
Levine, J. S., & Miller, K. R. (2008). Chordates. In Prentice hall biology. Retrieved March 5, 2017, from http://www.jayreimer.com/TEXTBOOK/iText/products/0-13-115516-4/ch30/ch30_s1_1.html
Lima-de-Faria (1)(2), A. (2011, December 5). The symmetry of birds emerges as the expression of an uninterrupted atomic order. Retrieved March 5, 2017, from https://link.springer.com/chapter/10.1007%2F978-3-642-25301-0_9
Macklin, M. (2015, May 29). DDT, the California condor, and a decades-long battle with a banned pesticide. Retrieved March 5, 2017, from http://www.onegreenplanet.org/environment/ddt-the-california-condor-and-a-decades-long-battle-with-a-banned-pesticide/
Switek, B. (2011, August 26). An ode to Archaeopteryx. Retrieved March 5, 2017, from http://www.smithsonianmag.com/science-nature/an-ode-to-archaeopteryx-63181085/
Thomas, A. L. (1997). On the Tails of Birds. BioScience, 47(4), 215-225. doi:10.2307/1313075
Thompson, M., & Russell, M. (2014). All about feathers. Retrieved March 5, 2017, from https://academy.allaboutbirds.org/all-about-feathers/
Yeoman, B. (2016, April 13). Why the passenger pigeon went extinct. Retrieved March 5, 2017, from http://www.audubon.org/magazine/may-june-2014/why-passenger-pigeon-went-extinct