Don't Mess with Mama

[John Chardine]

Hi James- You are right on the money and so is Axel. Great start to the forum because I can bring up life-history strategy! First, though, this is a great image with the crow having two points of contact with the nasty heron (see below).

Some species are long-lived and tend to produce small numbers of offspring every year. Some are short-lived and produce large broods. Across species there is a trade-off between life-span and annual output of young. Having kids takes years off your life!!

So, if there is any risk to a small bird attacking a larger predatory one, species that do not live long will tend to take big risks to save their offspring. Long-lived species tend to "shrug their shoulders" and wait for another year. For them it is very important that they live to reproduce again so they are not risk-takers when it comes to their own lives.

The image of a crow beating up on a heron is quite typical. Herons have a bad rap in the bird world, whether deserved or not, and often elicit mobbing reactions in other birds. Night-Herons are a real threat to many species. For example, they will visit a tern colony at night and gobble up as many chicks as will fit in their stomachs (I've heard of workers finding 20-30 tern chicks in their stomachs). Needless to say, anything that looks like a heron gets mobbed by terns at the colony.

Final thought- maybe it's not so risky for a small bird to chase a large predatory one like an eagle, so long as the smaller one makes a lot of noise and keeps the larger one on the run.

[Ákos Lumnitzer]

Hi James- You are right on the money and so is Axel. Great start to the forum because I can bring up life-history strategy! First, though, this is a great image with the crow having two points of contact with the nasty heron (see below).

Some species are long-lived and tend to produce small numbers of offspring every year. Some are short-lived and produce large broods. Across species there is a trade-off between life-span and annual output of young. Having kids takes years off your life!!

So, if there is any risk to a small bird attacking a larger predatory one, species that do not live long will tend to take big risks to save their offspring. Long-lived species tend to "shrug their shoulders" and wait for another year. For them it is very important that they live to reproduce again so they are not risk-takers when it comes to their own lives.

The image of a crow beating up on a heron is quite typical. Herons have a bad rap in the bird world, whether deserved or not, and often elicit mobbing reactions in other birds. Night-Herons are a real threat to many species. For example, they will visit a tern colony at night and gobble up as many chicks as will fit in their stomachs (I've heard of workers finding 20-30 tern chicks in their stomachs). Needless to say, anything that looks like a heron gets mobbed by terns at the colony.

Final thought- maybe it's not so risky for a small bird to chase a large predatory one like an eagle, so long as the smaller one makes a lot of noise and keeps the larger one on the run.

Great informative post John. Thanks - by the way - for directing me to this. :) Interesting as you say that long-lived species 'shrug' their shoulders. For example an Australian Magpie (a species of butcherbird really - Cracticus tibicen) is a common bird, beautiful too, and may live 25-30 years. In that time a female apparently is lucky to raise TWO young that end up successfully reproducing themselves or so I recently read in a book written by a professor, who spent 10 years compiling the info for her great little reference book. So every year out of a brood of four/five most will not survive to successful adulthood. Sad, but that is how it is isn't it? Maggies (as we Aussies affectionately call them) are far from being endangered. :)

Great pic too James by the way. Good find. :)