NOTES ON HOLE SIZE: 1  per Bergmann's rule, some species of birds may be larger in colder climates-e.g., a Canadian starling may be bigger than a Florida starling, thus the Canadian bird might not be able to fit in a certain hole size that its southern version could squeeze into.
A heart palpitation is the sensation that your heart has skipped a beat or added an extra beat. It may feel like your heart is racing, pounding, or fluttering. You may become overly aware of your heartbeat. This sensation can also be felt in the...
Causes of Heart Palpitations. Many things can cause heart palpitations. In the vast majority of cases, the cause is either related to your heart or is unknown. Non-heart-related causes of palpitations include: 1  Strong emotions such as anxiety, fear, or stress; palpitations often occur during panic attacks.2  Vigorous physical activity.therosclerosis is the process of narrowing and hardening of the arteries due to plaque buildup in the inner lining of arteries. It's the key cause of heart attacks and strokes and the No. 1 killer in the U.S. When it comes to developing health risks from atherosclerosis, some people are at higher risk than others.