“It’s not good to be big in a warming world,” stated Poland’s University of Wroclaw Biologist, Lucyna Halupka.  

Over the last few millenniums we have observed evolution and its surviving favorites–favoring those smaller than most, giving unique characteristics to survive whatever Earth has in store. Now this statement is coming farther into the light, showcasing the true survivors of the bird species. Due to climate change and the warming of the planet's surface temperature, many habitats have been negatively altered and will subsequently fail the rebound of springing back. One of these affected species is the variety of bigger birds. According to a study published in the Proceedings of the National Academy of Sciences (PNAS), smaller birds have an overall high success rate in reproducing in warmer climates. The global study observed and took data on over 100 species and their fledgling rate over the course of 50 years. 

Unfortunately through the findings, larger birds such as hawks and storks have been producing fewer surviving chicks. Over two pounds if sedentary and two ounces if they migrate–these groups laid smaller “clutches” of eggs and lost more chicks after hatching. Particularly on migrating birds, the researchers saw a 17% drop in the offspring success rate. This heavy decrease coincides with multiple reasonings, one being the mass extinction of birds throughout the decades. But, the more heavily observed option is that some species of birds are more likely to adapt to an ever-changing world–one with higher human contact, urbanization, and other external factors. Smaller birds evolve quicker and have been seen to produce 10% more successful chicks. 

Anatomically, the larger the animal, human, or creature, the harder it is to shed heat, making them struggle with cooling their body temperature. This natural occurrence is why we are seeing such a shift in the larger bird species–these birds can't keep in tandem with the warming climate. Smaller birds have also been seen to live shorter life spans, with a higher reproduction rate and quantity. About 56% of the total observed species have fallen victim to declines, the remaining ratio has found ways to thrive on this warming Earth. Those in decline were heavily spread throughout Europe and parts of Alaska. 

Due to these new findings and the potential room for more research, we may see more declines in the upcoming years, maybe not just in larger birds but larger mammals as well. The globe's warming temperature is not only detrimental for these generations, but for all the generations to come.