Transcript Avian diversity: Seabirds

Seabirds
Procellariiformes, Gaviiformes, Sphenisciformes, Pelecaniformes, and
Charadriiformes = 320 spp.
Water > 67% Earth’s surface but seabirds ~ 3% bird spp
Some differences between sea and landbirds:
- Most feed from the ocean
- Nasal glands for expelling brine
- Vary in their dependence of land, but all must return to land to breed
- Others hardly ever settle on water (Sooty Tern, frigates) and continuously on
wing away from land
- Active at night
Order: PROCELLARIIFORMES
Tube-nosed Seabirds
4 Families
Diomedeidae – Albatrosses
No. Pacific and So. Oceans
2 Genera, 14 Spp
(All threatened or worse)
Procellariidae – Shearwaters,
petrels, and fulmars
All Oceans
14 Genera, 76 Spp
Hydrobatidae – Storm petrels
All Oceans
7 Genera, 21 Spp
Pelacanoididae – Diving petrels
So. Oceans
1 Genera, 4 Spp
Wandering Albatross – Diomedea exclans
Northern Fulmar – Fulmarus glacialis
Peruvian Diving-petrel –
Pelecanoides garnotii
Wilson’s Storm Petrel –
Oceanites oceanicus
Greater Shearwater –
Puffinus gravis
Sulidae – Boobies, Gannets
All Oceans
3 Genera, 9 Spp
Blue-footed Booby –
Sula nebouxii
Northern Gannet – Morus bassanus
Order: PELECANIFORMES
Phalacrocoracidae – Cormorants
All Continents and Oceans
1 Genera, 38 Spp
Order: CHARADRIIFORMES I: non-seabirds
Shorebirds, Gulls, and allies
18 Families
85 Genera
> 300 Spp
American oystercatcher –
Haematopus palliatus
Haematopodidae: 1G, 11 Spp, Worldwide
Spotted Dikkop – Burhinus capensis
Burhinidae: 1G, 9 Spp, except NA
Double-banded Sandgrouse –
Pterocles binictus
Pteroclidae: 2G, 16 Spp, Old World
American Avocet – Recurvirostra americana
Recurvirostridae: 3G, 10 Spp, All continents
Scolopacidae – sandpipers and allies
21 Genera, 88 Spp - Worldwide
Wilson’s phalarope – Phalaropus tricolor
Upland Sandpiper - Bartramia longicauda
Greater Painted-snipe –
Rostratula benghalensis
Charadriidae – plovers, lapwings
10 Genera, 66 Spp - Worldwide
Blacksmith Plover –
Vanellus armatus
Black-bellied Plover – Pluvialis squatarola
Hudsonian Godwit–
Limosa haemastica
Rhynchokinesis
Independent opening of
the distal upper jaw
Common Snipe
Hudsonian Godwit–
Limosa haemastica
Niche Differentiation – Bill size and shape determines habitat and prey
CHARADRIIFORMES II: seabirds
Laridae – Gulls and terns
13 Genera, 95 Spp - Worldwide
Stercorariidae – Jaegers
2G, 8 Spp, Polar regions
Parasitic Jaeger –
Stercorarius parasiticus
Ross Gull –
Rhodostethia rosea
Black-legged Kittiwake –
Rissa tridactyla
Little Tern –
Sterna albifrons
Alcidae – Auks, murres, puffins
12 Genera, 23 Spp – Northern Oceans
Tufted Puffin – Fratercula cirrhata
Razorbill – Alca torda
Order: SPHENISCIFORMES
Spheniscidae
Penguins – Southern Oceans
6 Genera
17 Spp (~50% threatened or worse)
Parallel Evolution wing-propelled
divers in the two hemispheres
gull
Great
razorbill auk
Penguin
Niche separation in the Seabirds
Distribution of seabirds is governed by:
(1) latitudinal marine zones
(2) distribution of food in the zone
(3) nesting sites - safe nesting cliffs, islands, promontories
(4) distance of nest to food sources
Another difference between land and seabirds is distance flown to food – 100m to
several km for landbirds to 10s, 100s, or 1000s km for seabirds
Procellariiformes are the most pelagic and the capacity to exploit distant food
supplies is aided by:
(1) lower body temp (38 vs 41 degrees)
(2) Subdermal fat and stomach oil
(3) Flying style (dynamic and slope soaring)
(4) Well-developed olfaction
(5) Young resist chilling and become torpid
Marine zones and productivity
9 marine water zones (life zones)
Cold water has more nutrients and O2 and thus support more life
Weak winds in the tropics means productivity is 1% that of temperate coastal
water. The highest productivity being in polar areas and around continental shelves.
Seabird distribution across marine zones
The wide expanse and productivity cold southern oceans is where seabirds reach
their max abundance of individuals. Procellariiforms, dominate this region
– partially due to short food chains, krill, and loss of krill-feeding whales.
Auks, penguins, diving petrels are the only
major seabirds that failed to colonize both
hemispheres – and interestingly they also show
the most striking evolutionary convergence.
All spp hunt by “flying” underwater and this
may explain their absence form cold water.
A change in water temp of 5 to 15 degrees
doubles the swimming speed of exothermic
fish, but doesn’t change the speed of endothermic
birds.
Foraging zones (2-dimensional)
- Inshore (6-8 km from the sea)
- Offshore (coast to edge of continental shelf)
European Shag: 7 km trips of 6 hrs
(Scotland)
Common Tern: 30 km trips of 2 hrs
(Wadden Sea)
Black-legged Kittiwake: up to 60 km and 6 hrs
(Alaska)
Northern Gannets: 232 km (540 max) in 13-84 hrs
(Scotland)
- Pelagic (over deep ocean)
Wandering Albatross
S. Georgia to S. Brazil
(26°S to 67°S)
S. Chile to S. Indian Ocean
(17°W to 85°W)
6091 km/trip; 1534 km from nest
gone for 11.6 days
----------------------------------------------------------------------------------------------Fasting (for young and parent left behind) is associated with these trips
Galapagos penguin: < 3 days
Magellenic and King: 25-40 days
Emperor: walk 150-180 km to open water, forage 500 km, fast for >110 days
----------------------------------------------------------------------------------------------Foraging zones (3-dimensional)
Species differ in whether they obtain food below the surface and
the depths and length of time they can remain submerged
Here, auks and penguins are the most marine spp.
The best human diver can dive 100 m in 4 minutes.
King and Emperor Penguins: 304 and 534 m, respectively
and 7.5 and 15.8 min, respectively
Most seabirds nest colonially and sometimes in great numbers, In general,
nest-sites are of much greater biogeographic importance and limiting factor
to population size than is the case for landbirds.
Breeding and life history
Most seabirds are long-lived (30 or more years) and don’t breed until several years
old. Breeding may take a long time (up to 1 yr in large albatrosses) and occurs only
every other year.
Many (Procellarids, Alcids) lay a single large egg (up to 25% of adult mass)
Both parents incubate or otherwise care for young
Most (Alcids are an exception) regurgitate partially digested food or provide
stomach oil
Pairbonds remain as long as both parents are alive, although divorce can occur,
most frequently after unsuccessful breeding.
This pattern of life history (reproductive and survivorship schedule) means that most
populations are slow-growing and vulnerable to sudden collapses in population size
(i.e., recovery is very long). Alternatively, their long life spans allow them to buffer
short-term collapses in food supply that shut-down reproduction (e.g., El Nińo events).