English: This graph depicts how climate change interferes with bird reproduction.

1. As temperatures begin to rise in March, food availability increases, because the weather is warm enough for insects (the primary food of birds) to hatch. 2. Peak food availability occurs in June, as the young birds are growing and require food. 3. Because of increased temperatures caused by climate change, peak food availability begins in April. 4. Without climate change. birds lay their eggs at the time when peak food availability begins, maximizing the amount of food for the young. With climate change, peak food availability has already occurred when the baby birds hatch, meaning the young have fewer months with peak food availability, thereby decreasing their chance of survival.

Micro-Essay: In recent years, scientists have found increasing evidence to show that climate change has negative impacts on biological systems. One such negative impact is on reproductive habits of birds. Birds typically lay eggs in the late spring, depending on the region in which they live. In order to maximize the chance of survival of their young, birds synchronize their reproductive period with when there will likely be the most food available for the young. They coordinate this synchronization by using a photosensitivity system. As days get longer in the spring, birds can sense the change in the duration of daylight. This initiates a biological change that causes ovulation, because longer days indicate that spring is coming, meaning it is the appropriate time to lay their eggs. Climate change has greatly affected this finely tuned system. Due to climate change, temperatures are increasing earlier in the year. In turn, other species are reproducing or hatching earlier in the year. For example, many insects can now hatch in late February or March in some climates, because the average temperature during those months has increased significantly. This indirectly affects bird reproduction. Although birds utilize varied climatic or sensory cues to begin reproduction, photosensitivity is one of the most significant methods. However, climate change does not affect photoperiod, or the length of days. As a result, birds are not adapting to the changes to the environment and their food sources caused by climate change. Whereas insects, which birds need for food, are hatching earlier in the year in response to climate change, birds are not adapting in the same manner. Therefore, many birds and their young face limited or decreased food sources, as the birth of the young is no longer synchronized with maximum food availability. In the future, if birds that rely on photoperiod to initiate ovulation do not adapt to the change in seasonal temperature caused by climate change, their survival may be in danger.

Sources Carey, C. (2009). The impacts of climate change on the annual cycles of birds. Philos Trans R Soc Lond B Biol Sci, 364(1534), 3321-3330. doi: 10.1098/rstb.2009.0182

Lemonick, M. D. (2010, February 14). Can Climate Shift the Biology of Ecosystems? Retrieved May 19, 2017, from http://content.time.com/time/health/article/0,8599,1964085,00.html