how do ground nesting birds manage? (1 Viewer)

[Himalaya]

just how do ground nesting birds manage to nest and bring their offspring up with success.
in the uk they would face threats from foxes, weasels, stoats, rats, hedgehogs, squirrels, corvids, gulls, skuas - in some areas, buzzards, kestrels, harriers too name but a few! the biggest problem would be at night when foxes hunt right? then once the chicks hatch how do they manage to dodge the pitfalls along the way?

 

[Sancho]

I think another major hazard is a wet season. Ground nesting birds here took a bad hit in 2005, I think, when there were three days of torrential rain in July. A pair of breeding nightjars (rare as hell over here) lost their second brood as a result.

 

[Perry Grin]

how do ground nesting birds manage?

If they didn't................... they wouldn't!

 

[Capercaillie71]

how do ground nesting birds manage?

If they didn't................... they wouldn't!

I think that sums it up. It's easy to see ground nesting birds as victims of predation, but the relationship between predators and prey is like an arms race, where the prey species are often able to come up with strategies to reduce the effects of predators.

The most obvious strategy is to lay more eggs than you need. A Lapwing for example, may lay 4 eggs, but only 0.6 of those need to fledge to maintain a stable population. In other words, out of every five Lapwing nests, only three chicks need to survive to fledging.

Other ways of avoiding predators are careful concealment of nests, distraction displays, and colonial nesting, where large numbers of adults can often drive away predators.

Of course there are situations where, for example, non-native predators are introduced, or some (usually human-induced) change in land management shifts the balance in favour of generalist predators and predation can then become a problem requiring human intervention to prevent a gradual decline in some prey species.

 

[Pyrrhuloxia]

a major tactic is well camoflauged nests/evasive behavior.

I've done work with Grasshopper Sparrows in the northeast US. Their nests are INCREDIBLY difficult to find. You can be within 2 meters of one and it will still take anywhere from 15-45 minutes to find the nest itself. The adults are also very evasive, touching down quite a bit away from the nest and running across the ground when carrying food.

Despite it all, nest predation can still be a major problem. Especially if habitat is of low quality. Ground nesting warblers in the northeast US have been hit hard by extensive browse pressure due to an over abundance of white tailed deer. The lack of cover makes their nests much easier for predators to locate.

 

[Corax67]

Spent a lot of time ringing willow warbler and was constantly surprised by the ability to conceal a nest and the lengths the parents go to to land away from the site and walk in whilst feeding - mostly gave the nest site away by flying directly off the nest.

Similarly with Yellow Wagtail that nest in pastures adjacent to a river and yet the nests are never damaged by the cattle feeding in the same fields.

 

[Sancho]

One of the last Little Tern colonies here, on a shingle beach about 8km down the coast, was devastated last year, firstly by a high-tide with Easterly gales, and then by a fox, that got in despite the wardens best efforts. Including electric fence, round-the-clock monitoring, etc. So some ground-nesting species don´t aslways fare too well, and I suppose exposed shingle beaches are an odd option. Mind you, the previous year, they´d had a record number of birds successfully fledged.

 

[TomSmith]

A Lapwing for example, may lay 4 eggs, but only 0.6 of those need to fledge to maintain a stable population.

True, but this does rather assume you get 5 females and 1 male each time on average. More realistic would surely be 2 fledging? (Or have I got the maths wrong? - not unknown!)

 

[Himalaya]

It is amazing how ground nesters surive the odds. On spring watch we saw how the mink destroyed the moorhen nest. What could a flock of lapwings do to stop a fox at night? Ground nesters must be very patient while incubating eggs.

 

[luvdabirds]

Perry Grin sums it up above...

Life History traits tell much of the evolutionary story. Ground nesters in general lay many more eggs that tree or cavity nesters, in the "hope" that predators can't get all the eggs or they may get lucky one year.

Also, in many areas, the large areas of open lands do not exist anymore. Ground nesters are forced to nest in narrow edges (such as powerline & road right-of-ways). Nest predators can hunt for nests in these "linear" habitats more efficiently than in large areas.

 

[buckskin hawk]

In the garden of the entry of our church, last spring, a Killdeer laid her nest of eggs. It was a great tool to teach the children about them as the mother danced her broken wing dance. The nest was just inches from the sidewalk and I was so sure that the poor little bird wouldn't choose it for a second brood but she did.

 

[citrinella]

how do ground nesting birds manage?

If they didn't................... they wouldn't!

Yes but ...

There is some evidence that the big declines in birds we have seen over the last few decades was from a very high peak previously, and that peak was reached because of man's shooting interests and control of vermin. Control of ground predators - mustelids, foxes, badgers etc. might have been very important (even if control of raptors was not).

IIRC Chris Mead related the case of Holkham marshes something like this : the biggest peewit breeding colony in Britain, perhaps Europe (650 pairs ??) collapsed to a few pairs when gamekeepers were laid off 20-30 years ago. When farming income came under pressure in the late 90s shooting income was again actively sought, foxes were controlled and the peewit came back.

While Perry Grin's comment is true, the balance is not all that stable, and man can have a major influence.

On wet summers : and 2007 in our area. Skylark and yellowhammer in particular were visibly decimated, both from very healthy starting points. Grey partridge had a hard time, unfortunately from a relatively fragile position. Nationally the BTO nest record scheme has shown serious effects on other species such as blue and great tits.

Very wet periods in summer are predicted to increase in frequency due to global warming. This could have serious consequences, despite all our best efforts.

Mike.

P.S. I am not anti-fox. In fact, as a farmer I am pro-fox as they help keep down rabbits. As a conservationist I have mixed feelings ! Lovely to watch but ?

 

[Himalaya]

I wonder what woud happen if nature was allowed to take control and there were no predator/pest elimination programms?