Sea bird behavior and what it tells us

[DarkSkies]

"Gannets are plunge divers and will dive into the sea from heights of 100 feet or more in pursuit of
caplin, herring, mackerel, menhaden, squid, and other prey."
http://www.shltrip.com/Crossing_Delaware_Bay.html



[* Notice here it says "menhaden" which are bunker. I specifically looked for a quote describing all the fish gannets are known to dive for so people would learn that there are differences. Gannets will never pass a meal up of peanuts or juvenile bunker And there are times wehn they will feed on adult bunker if the bunker are not tightly schooled. As it says, they are opportunistic feeders. The "small anchovies" that others reported them diving on was more likely schools of large spearing, which we have recently noted to be in the area. I just wanted to clear that up. ]

[DarkSkies]

Gannet behavior I:

It's most likely that gannets found along our Eastern US coastline are northern gannets.

http://bna.birds.cornell.edu/bna/spe...s/introduction


Introduction

Adult Northern Gannets, with chick
Figure 1. Distribution of the Northern Gannet in North America.

This heavyweight among the plunge-divers of the world breeds in often huge, always dense, and extremely raucous colonies on precipitous mainland cliffs, islands, and stacks. As a breeding bird, the Northern Gannet is confined to the continental-shelf waters on both sides of the North Atlantic. In the eastern North Atlantic, it is distributed in 32 colonies from the coast of Brittany in France north to Norway, with its main concentration north and west of Scotland (Nelson 2002). In North America, it is restricted to just 6 well-established colonies: 3 in the Gulf of St. Lawrence, Québec, and 3 in the North Atlantic off the coast of Newfoundland.

This species is monomorphic, with sexes similar in size and appearance. Pairs usually bond monogamously for life, and both mates participate in all aspects of parental care, though sharing of the activities varies over the course of the nesting cycle. The species has a rich repertoire of picturesque sexual and aggressive behaviors for maintaining pair bonds and living in close contact with its neighbors. The female lays a single egg, which is incubated under the highly vascularized webs of the feet (gannets do not have a brood patch).

Hatchlings are altricial, with essentially no motor coordination or thermoregulatory capacity, but they develop rapidly during the 13-week nestling period, attaining peak weights at 8–9 weeks of age of up to 50% more than adults. At 13 weeks, chicks depart from nest sites by jumping from their nesting ledges and flying/gliding 400–500 meters from the colony into the water. Unable to rise from the water because of their excessive weight and still without fully developed wing muscles, they begin a southward migration to middle Atlantic regions. Mortality during the first year is high, but those birds that survive have a strong tendency to return during their second or third year to the same colony in which they were hatched.

Like other seabirds, the Northern Gannet takes several years to attain adult plumage, going through various stages of mottled dark-and-white plumages before becoming pure white with black wing-tips at 4–5 years of age. At maturity, the male begins the arduous process of acquiring a breeding site in the colony and attracting a mate. Once acquired, it is likely to be the pair’s nest site for the rest of their lives, where they will raise 1 chick per year. Reproductive success (that is, eggs producing fledging young) at colonies is generally high (>75%), and most colonies today are increasing in population size at a rate of about 3.0–3.5% per year.

The Northern Gannet is a voracious forager, feeding on shoaling fish by plunge-diving. As an opportunistic feeder, it utilizes prey species as they become available through the season, but prefers larger (more than 30.0 cm), more energy-rich (7.0 kJ/g) species over smaller, lower-energy species, and often forages up to several hundred kilometers from its nesting colony to locate such prey. The average annual harvest of squid and mackerel (Scomber scombrus) in Newfoundland by Northern Gannets often exceeds that of the total commercial landings (Montevecchi et al. 1988). Foraging is not without its risks, and mortality of adult gannets is fairly high as a result of fishing accidents, entanglement in nets, and, albeit less today than in the past, persecution by fishermen.

[DarkSkies]

Gannet behavior II

Gannets on pilchards






http://www.answers.com/topic/solan-goose-1
Ecology
Gannet pairs may remain together over several seasons. They perform elaborate greeting rituals at the nest, stretching their bills and necks skywards and gently tapping bills together.

They are migratory and most winter at sea, heading further south in the Atlantic.

These birds are spectacular divers, plunging into the ocean at high speed. Although they are pul and agile fliers, they are clumsy in takeoffs and landings. They mainly eat small fish (2.5-30.5 cm in length) which gather in groups near the surface. Virtually any small fish (roughly 80-90% of the diet) or other small pelagic species (largely squid) will be taken opportunistically.

**Various cod, smelt and herring species are most frequently taken.[4]

Although Northern Gannet populations are now stable, their numbers were once greatly reduced due to loss of habitat, removal of eggs and killing of adults.
Predators of eggs and nestlings include great black-backed and herring gulls, common ravens, ermine and red fox. The only known natural predator of adults is the bald eagle, though large sharks and seals may rarely snatch a gannet out at sea.[5]

Old names for the Northern Gannet include solan, solan goose and solant bird.





Gannets on sardines

[finchaser]

listen up cause SOS knows birds

[gjb1969]

hey dark u are going to open upa can of worms with the bird stuff get worms bird stuff

[CharlieTuna]

Don't worry about the ball busting Dark, you know that's because we like you. I think you did a good job with the gannet info. And you are right, I am amazed at how many people confuse seagulls with gannets. Online research is so easy now. When I grew up we had to go the library to do this stuff.

[baitstealer]

The birds tell us when SOS is around doing his scouting.

[storminsteve]

listen up cause SOS knows birds

I guess you really do know your birds DS. Grats to you and Stripercoast for laying down this info. I saw birds the other day, not many fish under them. But last week in ocean county I saw gannets diving just beyond our casts. I also saw boats in the area hooking up, I'm assuming they were over bass and some kind of big bait.
It's a thrill to watch them kamikaze dive into the water. I checked out that other thread you have highlighted too. Thanks guys for sharing your knowledge.

[Pebbles]

http://www.cartoonstock.com/directory/s/seagulls.asp

[DarkSkies]

hey dark u are going to open upa can of worms with the bird stuff get worms bird stuff

What can I say, G!

And Pebbles, what can I say, she can bust me anytime, special priveleges....


*****
I came across a large body of bait the other night, in 46 degree water...with a few hundred birds sitting on them. the birds wouldn't move despite the diffulty they had in maintaining their position.

In situations like that, it's always a good idea to work the area for predators, There weren't many there, but at least I worked it hard to find that out....

Thanks again to Ed for his perspective as well.

[DarkSkies]

Birds and Winter Herring......

Back in late December when the water was a little warmer there were schools of herring......
Most of these schools didn't have bass under them, they just moved up and down the coast....

As opposed to bunker, which sometimes stay closer to the surface as they feed, these herring were only visible by looking for a dark stain....

The birds could see them, though....with crystal clear clarity and perfect vision they would gather around the schools waiting for something to happen...it often never did, but the birds would wait anyway......

The following are pics I took one such cold dreary morning....

Thought some of ya's might like to see what I saw, the subtle signs......