Sea bird behavior and what it tells us

[plugcrazy]

Seagulls and Salmon




working the birds

[DarkSkies]

Thanks for posting up the videos, Plugcrazy. Gunny/Stripercoast1 also put up a good thread about birds and the 3 types of blitzes. I thought of that after I posted this thread. I thought of combining them, but his is pretty specific and deserves it's own space, good read.

Here's a link to it:
http://stripersandanglers.com/Forum/showthread.php?t=5061

[vpass]

I have also seen seagulls near the water edge feeding on beached peanuts. from a distance it look like they where just sitting around, but what was out of place was the wind was blow NW and they where face E. Seagulls almost alway face the wind. I investigated and got into a memorable blitz. It was this time of the year 2003.

[cowherder]

Seagulls almost alway face the wind. I investigated and got into a memorable blitz. It was this time of the year 2003.

I never noticed that until I read it here. I did notice that when they are gathered up on the shore it means either bad weather is coming or they are waiting for food at some future time. Like they may have seen baitfish yesterday for an hour, and they show up today because those baitfish might show up today. Thanks vpass.

[DarkSkies]

I'm posting this to help to educate us about what kinds of birds gannets are, what they eat, and what their behavior means.

I decided it was necessary because at a few other places there are some people talking about the following:

1. Gannets diving on adult bunker.
2. Gannets being in the RB on small bait "like bay anchovies".

I don't want to get into pizzing contests with anyone here or in cyberspace. If the above scenarios are what the people reporting them believe they saw, it's certainly possible. But realistically, I think we need to educate people as to the behavior and feeding habits of gannets so people have a better idea of what they're seeing and why they're seeing it...

(and if they saw gannets at all. It's quite common for some people to confuse seagulls with gannets.)

However, if you have been around and fishing for a number of years, you learn to distinguish the difference. To me, there is no mistaking the dive bombing Kamikaze ferociousness of gannet behavior.

I love watching them crash on bait, knowing that often there are big bass underneath. Frequently the gannets are the only indicator that the bass are there, as feeding bass will sometimes not even break the surface if there are only a few bass and the school of forage fish is large enough.



To begin with, gannets take a high speed dive into the water to get their food. It's a pretty cool sight to watch. They primarily feed on herring and similar sized bigger bait in the ocean because that's the right size food for them. They could kill themselves if diving on tightly packed schools of horse bunker. They do eat adult bunker given the right conditions.

As for smaller bait like anchovies, it might be possible, but they would rather eat herring and bait in that size range. The ideal size range is indicated in bold below. I did this to show that all things are possible, but you have to ask yourself as a fisherman which scenarios are likely.

That's why when spotted in early Spring and late Fall they're a great indicator of herring schools. You see them a lot early and late season when the herring are moving through an area. As mentioned, they could also be on bunker, if the bunker are not densely packed.

You can see them in the deeper bay waters, or the ocean. Whenever you see them, it's an awesome sight.

[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.