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Osprey

Pandion haliaetus

Order:
Accipitriformes
Family:
Pandionidae
Sections

Diet and Foraging

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Feeding

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Ospreys typically carry fish with the head held forward.

© Brian Sullivan, California, United States, 6 March 2011
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An Osprey holding a fish on the ground prior to consuming.

© Lauri Taylor, Utah, United States, 6 May 2016
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Close-up of an Osprey carrying a fish.

© Richard Merrigan, Florida, United States, 14 March 2016

Main foods taken

Live fish account for over 99% of prey items recorded in almost every published account, with a wide variety of species taken. A survey of the foraging literature (including Bent 1937b, Palmer 1988e, Poole 1989a, and references cited here), covering freshwater and saltwater habitats across much of the species' North American range, reported over 80 prey species taken. In 13 studies conducted in freshwater habitats from Michigan, California, and the Pacific Northwest, over 30 species listed (average about 5 species/study), but the vast majority of fish taken in any one area often consists of only 2 or 3 of species (Vana-Miller 1987; see Appendix 1 ). Ospreys using saltwater habitats also appear to concentrate on a few fish species, and may take a lower diversity of prey overall than those hunting in freshwater habitats, although few studies of diet have been conducted in saltwater habitats (see Appendix 1 ).

Microhabitat for foraging

Varies greatly; along coasts in saltwater marshes, lagoons and ponds, estuaries, silted river mouths, coral reefs, and only rarely in deeper, offshore water. For example, Ospreys in Nova Scotia reported feeding 1.5 km offshore on fall runs of mackerel (Scomber spp.; Greene et al. 1983), and in coastal Senegal, feeds 1–5 km offshore for sardines (Sardinella spp.) and flying fish (Cheilopogon spp.; Prevost 1982).

In inland areas, forages along rivers, marshes, reservoirs, and natural ponds and lakes, where individuals feed in both shallow littoral zones as well as in deeper water. Adults at one lake in Florida preferred foraging in shallow water near shore, while recently fledged young had no preference for deep versus shallow water (Edwards 1989b). Nesting densities higher near shallow-water environments suggesting a preference for such areas (fish can be caught in deep water only when they occur near the surface or are driven to the surface).

Foraging is less efficient and successful in water with thick emergent and submerged vegetation (Postupalsky and Stackpole 1974, Prevost 1977). Reservoirs often provide ample expanses of shallow, clear water—ideal conditions for hunting (Swenson 1981, Vana-Miller 1987), although periods of low water can lead to reduced prey availability owing to prolific growth of aquatic vegetation (S. Postupalsky in Vana-Miller 1987).

Food capture and consumption

Figure 2. While hunting on the wing over open water, flaps or glides, usually 10–40 m above the water. When fishing offshore, may climb to 200 m to locate schools and then drop down to begin hunting (Prevost 1982). When spotting a fish, often hovers prior to diving, then plummets, legs extended forward just before plunging feet-first into the water. Where fish are schooling, may rarely capture more than 1 fish in a single dive (e.g., Mclean and Byrd 1991a).

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Figure 2. Osprey foraging dive.

Because Ospreys can dive only a meter or less deep, they are restricted to surface-schooling fish, or to those in shallow water. Photo by D. Nill from Schmidt 2001, used with permission.

Different angles of attack observed for different types of fish—long, shallow dives for fast-swimming fish near the surface, steeper dives for slower fish in deeper water (Prevost 1982). Also dives from “interhover” flapping or gliding flight. Capture attempts more often successful from a hover than when initiated by individual moving forward (Grubb 1977b). Also hunts from perches when available. All capture attempts over a warm-water marsh in southeastern British Columbia were made from flight, while 26% of dives in nearby Kootenay Lake were from perches (Steeger et al. 1992). Hunting from perches may be more frequent on overwintering grounds, where individuals can tolerate a lower prey encounter rate because they are not feeding young or mate (Poole 1989a). In a particularly unusual example, an Osprey was observed catching flying fish from a perch in the rigging of a research vessel in the Pacific Ocean, over 1,000 km off the west coast of Mexico (Rogers and Leatherwood 1981).

In very general terms, comparisons of the ecology of fish taken by Ospreys over a broad expanse of their range showed that benthic-feeding fish (taken only in shallow waters) are the easiest to catch, and that in the limnetic-zone piscivorous fish are harder to catch than nonpiscivorous fish (Swenson 1979b). Benthic feeders may have their attention focused down on food, rather than up where the Ospreys are, and limnetic piscivores are faster than nonpiscivorous fish.

Powerful wing strokes are needed to take off after prey capture while partially submerged in water with a heavy load; prey typically represents about 10–30%, but may be over 50%, of the body mass of an Osprey. Prominent deltoid process on humerus and relatively long manus may be adaptations for getting airborne out of the water and/or for extensive hovering flight (ROB). Once in the air, fish is maneuvered in feet to be aimed forward, using fish’s hydrodynamic streamlining to reduce aerodynamic drag. Fish are usually taken to an elevated and prominent perch, often near the nest, where eaten.

Cloud cover, sun brightness, and precipitation did not affect foraging success of male Ospreys in British Columbia, while correlated wind speed and water-surface conditions (calm, rippled, or choppy) did (Machmer and Ydenberg 1990). As wind speed increases, Ospreys glide more and spend less energy in flapping flight, but hunting bouts become longer and less successful, such that hunting in winds > 7 m/s (25.2 km/h) may not be energetically profitable (Machmer and Ydenberg 1990). Migrating Ospreys foraging in a shallow bay in southern New York State caught more fish in full sun than in shade, and foraging success was slightly but significantly less in winds > 24 km/h than on calmer days (Decandido 1991).

Mean dive success (24%) reported by Machmer and Ydenberg 1990 was at the lower range of a review of 13 studies of Osprey foraging efficiency (19–69%; Swenson 1979b). In spring and summer in southern Humboldt Bay, California, 82% of 639 hunting efforts were successful (56% on first dive); average time spent hunting before a capture was 11.8 min. Relative success on incoming and outgoing tides changed through the course of the breeding season (Ueoka and Koplin 1973)

In northeastern Nova Scotia, numbers of foraging Ospreys and dives made were highest at dawn and dusk; and highest at midtide, regardless of tidal direction (Flemming and Smith 1990). Success rates of dives did not vary through the day (50–74%), but was highest at midtide (70%), relative to high or low tides. Surprisingly, a weak tendency for higher dive success was seen when water was murky, perhaps because attacks were directed at fish close to surface. Rain decreased the number of Ospreys foraging, compared to cloudy or sunny conditions, and cloud cover did not affect the rate of encounter with prey (as measured by number of dives) nor success rate/dive. At a lake in Florida, by contrast, cloud cover (and amount of surface chop) reduced the rate of encounter with fish but not success rate/dive (Grubb 1977c).

Fledged young are rarely near their parents except when receiving food, so they do not learn to hunt by watching their parents (e.g., Edwards 1989b). However, Szaro 1978 witnessed young following parents to feeding shoals at Seahorse Key, Florida, where parents dropped food, which young would dive to recover from water. Siblings will hunt together after fledging and get better at hunting sooner than single young do (most pronounced difference at 90–120 d postfledging), but latter eventually catch up and show no difference in hunting behavior or success from siblings that hunted together (Edwards 1989b).

At a nesting colony in Halifax, Nova Scotia, Ospreys preferentially left the colony in the direction of individuals seen returning with fish likely to be concentrated in schools (alewives [Clupeus harengus], pollock [Pollachius virens], and smelt [Osmerus mordax]), as opposed to winter flounder (Pseudopleuronectes americanus), which are more randomly distributed (Greene 1987). This implies that a benefit of colonial nesting may be increased foraging efficiency through information gained from fellow colony members. Birds returning from successful hunts for the schooling species gave a stereotypic flight display, often after a period when no fish had been captured by colony members, eliciting a dramatic response from all non-hunting birds in the colony (Greene 1987), and those foraging for flounder would abandon the area being hunted and head off in the direction of birds arriving with schooling species (Greene et al. 1983). On a migration stopover at a bay in western Long Island Sound, New York, perched Ospreys were also seen to backtrack individuals bringing in schooling species, while individuals already foraging would move to an area where other Ospreys were seen circling and diving (Decandido 1991).

In contrast, (Hagan and Walters 1990) found no such information transfer at a North Carolina colony, perhaps because fishing grounds were over 10 km from the colony, so any information available from an incoming male was outdated. (Flemming et al. 1992) suggested that Ospreys at a colony in Nova Scotia increased their foraging efficiency by moving to areas where other Ospreys were hunting (“local enhancement”) and foraging in “flocks” (two or more Ospreys foraging within 200 m of each other). Foraging in flocks reduced both mean and variance of time spent between dives, but not average success of each dive.

Diet

Studies of diet usually rely on observations of individuals hunting or the identification of prey remains collected underneath nests, and are thus subject to a number of biases. When analyzing prey remains (especially opercula, tails, and fins) under nests or perches, researchers should note that small prey items may be consumed entirely and thus be underrepresented in the sample, and large remains may be carried off by scavengers (Prevost 1982, Poole 1989a). These biases can be avoided by placing wire cages beneath feeding perches to collect dropped remains (Prevost 1982), but few studies have gone to this length. Field tests of identification of prey by observers in Scotland showed accurate identification of prey species, albeit with consistent inter-observer differences in ability to estimate fish length of smaller specimens, which in turn could have significant effects on calculations of energy budgets (Carss and Godfrey 1996). The proliferation of nest cameras with legions of avid followers may provide a wealth of observational data on prey delivery rates and prey species used. This is an ideal opportunity for a significant contribution in citizen science. The Explore.org developers have initiated an exemplary program following a nest in Bremen, Maine (http://explore.org/live-cams/player/osprey-nest).

Major Food Items

Inland populations may feed on the same species throughout breeding season (Swenson 1978, Vana-Miller 1987; see Appendix 1 ), although some will switch preferred prey (and consequently foraging habits) with shifts in availability (Edwards and Collopy 1988). Diet of coastal populations typically changes in response to migrations of prey; e.g., in the northeastern U.S., Ospreys may switch to winter flounder when schooling species such as herring (Alosa spp.), menhaden (Brevoortia tyrannus), or pollock (Pollachius spp.) leave the area (e.g., Greene et al. 1983). In inland habitats, a wide variety of fish species can represent the 1–3 dominant species in the diet of a local Osprey population (see Appendix 1 ).

Fish captured generally weigh 150–300 g and measure about 25–35 cm in length (range 50–1,200 g; Cramp and Simmons 1980b, Prevost 1982). In Idaho, fish captured were mostly in 11- to 30-cm size classes (Van Daele and Van Daele 1982).

Anecdotal observations of Ospreys with non-fish prey include birds, snakes, voles, squirrels, muskrats (Ondatra zibethica), salamanders, and even a small alligator (Alligator mississippiensis; Wiley and Lohrer 1973, Proctor 1977, Thorpe and Boddham 1977, Castrale and McCall 1983, Taylor 1986d, King 1988, Poole 1989a, Pawloski 1996, Watermolen 1996, Douglass 1997). An Osprey was observed foraging by walking along the ground and sallying out 2 m to capture ground squirrels (Citrellus sp.; Werren and Peterson 1988). Some of these reports include non-fish taken in water, probably using typical foraging techniques (e.g., alligator, muskrat) and emphasizing the generalist nature of Osprey predation while hunting over water; some may result from Ospreys trimming their nests with skeletal remains and thus not represent prey taken. Bad weather (high winds, choppy or turbid water) or early arrival on breeding grounds (when lakes are frozen) may promote such behavior; e.g., feeding on dead and dying fish tossed on the ice by fishermen in Georgian Bay of Lake Huron (Ewins and Cousineau 1994).

Ospreys rarely scavenge dead or dying fish (Dunstan 1974, Poole 1984), and even less frequently feed on terrestrial carrion. One was reported on a white-tailed deer (Odocoileus virginianus) carcass in New York State (B. Loucks, personal communication), and an Osprey was seen feeding with a group of Turkey Vultures (Cathartes aura) on a road-killed opossum (Didelphis virginiana), which the Osprey tried to carry away when flushed (Dusi 1995).

Quantitative Analysis

In North America, nearly all quantitative studies have been based on observations of breeding birds, and data in most are presented as percentages of total number of prey items observed. Swenson 1979a and Vana-Miller 1987 reviewed such data for a number of studies across a broad range of habitats, from the California coast, Pacific Northwest, and Yellowstone National Park to New England, Nova Scotia, and the Florida Keys (see Appendix 1 ).

In the Pacific Northwest (including northern California) and British Columbia, common carp (Cyprinus carpio), tui chub (Gila bicolor), largescale sucker (Catostomus macrocheilus), black bullhead (Ictalurus melas), brown bullhead (I. nebulosus), smelt (Osmeridae), surfperch (Embiotocidae), and cutthroat trout (Salmo clarkii) all represent the dominant prey species in at least one quantitative study of breeding-season diets (for numbers and citations, see Appendix 1 ) Other important species include mountain whitefish (Prosopium williamsoni), black crappie (Pomoxis nigromaculatus), and rainbow trout (Oncorhynchus mykiss). Collectively, trout and salmon (Salmonidae) ranged from 10.3 to 24% of the diet in 4 studies. An estuarine population in Alaska fed heavily (95%) on starry flounder (Platichthys stellatus). On the Willamette River, Oregon, prey remains at nest sites indicated that largescale sucker and northern pikeminnow (Ptychocheilus oregonensis) accounted for an estimated 90% of the biomass in the Osprey diet (Henny et al. 2003).

In western Washington, diet changed with season (and reflected changes in foraging location): the birds ate mostly hatchery-reared salmonids (Salmonidae; age 1 yr; 61.0% incidence [57.1% biomass]) before egg laying; then (during the nestling period) righteye flounders (Pleuronectidae) (30.5% [28.0% biomass]), carps and minnows (Cyprinidae) (primarily peamouth) (21.5% [19.3% biomass]), and salmonids (age 2-3+ year) (18.0% [34.4% biomass]) (Johnson et al. 2009a). Similarly in coastal southeastern Massachusetts, Ospreys eat primarily herring (Alosa sp.) before egg-laying and during incubation, when those anadromous fish migrate into fresh-water streams and ponds, then switch to a variety of marine fish (especially Atlantic menhaden [Brevoortia tyrannus]) during chick-rearing when Alosa move back to the sea (AFP).

In Florida, dominant prey species include gizzard (Dorosoma cepedianum) and threadfin (D. petenense) shad, sunfish (Lepomis spp.), crappies, speckled trout (Cynoscion nebulosus), and mullet (Mugilidae). Principle prey species for Ospreys in estuaries and coastal zone of the northeastern U.S. have included menhaden, winter flounder, alewives (Alosa pseudoharengus), smelt, and pollock.

Steeger et al. 1992 provided numbers, percent of diet by biomass, and kJ/fish for species taken in May through July in 2 habitats in southeastern British Columbia. In shallow, warm-water marshes near Creston, 3 most commonly taken species were black bullhead (38% of prey items, 44% biomass), pumpkinseed (Lepomis gibbosus; 35% items, 21% biomass), and yellow perch (Perca flavescens; 12% items, 12% biomass). At nearby Kootenay Lake, suckers (Catostomus spp.; 40% items, 78% biomass), mountain whitefish (21% items, 10% biomass), and rainbow trout (Oncorhynchus mykiss; 22% items, 8% biomass) were 3 most commonly captured species.

In Chesapeake Bay, diet of breeding Ospreys differed with habitat: populations in the lower bay (higher salinity) caught mostly Atlantic menhaden and sea trouts (Cynoscion spp.), those in the upper bay (lower salinity) mostly gizzard shad (Dorosoma cepedianum) and catfish (Ictaluridae) (Glass and Watts 2009). Upper bay diet averaged 40% higher in energy content than the lower bay diet; growth rates of populations (1970s through the 1990s) in these two regions reflected those differences, with significantly higher growth in the upper bay (Watts and Paxton 2007).

In Yellowstone National Park, Wyoming and Montana, Ospreys feed primarily on cutthroat trout (Oncorhynchus clarki bouvieri); breeding numbers and success were significantly correlated with abundance of this trout, 1987–2009 (Baril et al. 2013).

Little has been published on Osprey diet in Central and South America during the overwintering period. The only detailed study published to date reported mullets (Mugil spp.) and pompanos (Diapterus rhombeus), representing 76.7% and 17.8%, respectively, of 90 prey items recorded in mangroves of Santos and Cubatão, Brazil (Silva E Silva and Olmos 2002).

Other observations are anecdotal: Ospreys overwintering in the Sea of Cortez leave piles of skulls of coronet fish (Fistularia sp.) under feeding perches on Mexican giant cardon cacti (Pachycereus pringlei), and on the upper Texas coast, overwintering Ospreys take many saltwater catfish (Gafftops sp.; R. A. Behrstock, personal communication). E. Malaga (personal communication) observed Ospreys taking Mugil cephalus from lagoons along the southern coast of Peru. Twenty observations of Ospreys taking red piranha (Pygocentrus caribe) in the Venezuelan llanos (C. Sharpe, personal communication). M. Goulding (personal communication) reports observations of Ospreys taking peacock bass (Cichla sp.), arowana (Osteoglossum bicirrhosum), dogfish (Raphiodon vulpinus) and headstanders (Leporinus sp.) in Amazonia.

Food Selection and Storage

While some studies imply that Ospreys show no preference for particular species of fish (e.g., Flook and Forbes 1983), other studies found certain species were preferred. Ospreys reported to disproportionately catch bullheads and salmonids relative to netted samples, while northern squawfish (Ptychocheilus oregonensis), yellow perch, and largescale suckers were underrepresented in the diet (Van Daele and Van Daele 1982). At a lake in Florida, throughout an 18-mo study, adult Ospreys captured bass (Micropterus salmoides and Morone saxtilis) in proportion to their abundance, but took sunfish and shad (Dorosoma spp.) disproportionately, exhibiting a preference that switched from shad to sunfish and back again with rising and falling abundances of sunfish. The switch to shad accompanied a change in foraging location from nearshore to deeper water, despite equal abundances of shad in the 2 environments (Edwards and Collopy 1988). Distribution of shad in deeper waters was more even, so Ospreys encountered this species more regularly. In Yellowstone Lake, Wyoming, Ospreys preferred foraging over deep water where immature cutthroat trout (of the preferred prey size) were concentrated (Swenson 1978).

A study of development of prey choice among fledglings (up to 170 d after fledging) at a Florida lake found that siblings that stay together after fledging, developed similar prey preferences, while no similarities could be found among single fledglings without siblings (Edwards 1989b). Young in one year preferred smaller (20–30 cm) sunfish, but otherwise took other prey groups and size classes at random (equal to abundance as determined by electrofishing). Some young exhibited a preference for each of the 3 fish types (bass, sunfish, and shad), while some exhibited no preference at all. Preference patterns developed based on the first few captures and did not change throughout the study despite changing relative abundances of the prey base (which triggered adults to shift their preferred prey species), implying that young settle on one search image early and then work on perfecting foraging techniques such as dive height and angle.

Ospreys do not cache food. An individual can consume about 300 g (perhaps more; Prevost 1982) in a meal; will discard the uneaten portion of a fish in warm weather, but carry remnants of a fish around for a considerable time in cooler weather; partially eaten fish are often left at the nest (Poole 1989a). Ospreys do carry fish on migration (See Migration: Migratory Behavior, Diet and Foraging: Feeding).

Nutrition and Energetics

There are several estimates of daily energy expenditures and calculations of energy content of Osprey prey, the first being a study of overwintering Ospreys in western Africa (Prevost 1982).

Aside from water, fish flesh consists almost entirely of proteins and lipids, with lipids on a mass-specific basis providing more than twice the metabolizable energy (39.8 kJ/g or 9.5 kcal/g) available in protein (17.6 kJ/g or 4.2 kcal/g; King and Farner 1961). Additionally, some of this metabolizable energy is lost to heat in the assimilation process—the amount varying with the end use (maintenance and locomotion vs. fat accumulation; De Groote 1974 in Prevost 1982). Different fish species have different lipid contents as well as edible proportions, and hence different energetic value to an Osprey, so data on delivery rates of prey to a nest must include size and species involved, as well as lipid/protein ratios, if they are to be useful in energetic analyses or compared among different study areas.

For Ospreys overwintering in western Africa (Prevost 1982), foraging efficiencies were estimated from direct observations of birds capturing prey of known caloric content, and metabolic rates were estimated from various sources for roosting, resting, flying, and hunting, to calculate daily energy requirements ranging from 649 to 858 kJ/d for a 1.3-kg Osprey (an average male) and 1,252–2,387 kJ/d for a typical 2-kg female. Depending on estimated foraging efficiencies, these figures calculated to a required daily hunting time of usually < 30 min (range 16–75) for males and mostly < 60 min (range 20–220) for females.

Male Ospreys in Massachusetts (Poole 1984) providing food for themselves, a mate, and 3 young (20–30 d old), and estimated a required daily catch of 1,250 g, some 400 g of which (1,507 kJ) being the male’s share . Assuming a hunting efficiency (kcal/min hunting) of 5.5, slightly less than that used by Prevost 1982, the male would have to hunt on average 195 min/d to feed the family.

In Idaho, daily delivery rates of fish (mostly brown bullheads) averaged 4.6 to nests with 2 young and 5.6 to nests with 3 young (Van Daele and Van Daele 1982), similar to the 5.4 fish/d (mostly menhaden) reported for Ospreys in Chesapeake Bay (Mclean and Byrd 1991b) as well as other studies. In the Idaho study, energetic demands, estimated to be 794 g of fish/d for 2 young and 1 adult and 1,048 g/d for a brood of 3 plus 1 adult, closely matched observed food delivered.

Adult Ospreys need 1,197 kJ/d and young at time of fledging need 1,063 kJ/d (Lind 1976). Green and Ydenberg 1994 estimated that males provisioning 3-chick broods had a daily energy expenditure of 1,336 kJ/d (319 kcal/d), while males with single-chick broods expended on average 1,084 kJ/d (259 kcal/d). Mean daily energy expenditure (1,248 kJ = 299 kcal) in Green and Ydenberg’s study was well below calculated maximum sustainable daily expenditure of energy for a 1,428-g Osprey (1,913 kJ/d = 458 kcal/d; Karasov 1990). Males with 3-young broods had higher daily energy expenditures and delivered more food to the nest than males with single-young broods. All males together spent the vast majority of their time (81%) inactive.

Candler and Kennedy 1995 have modeled the energetics of Osprey migration—fasting (migration with no stops for feeding), jump (feeding at a few sites en route), or hop (frequent feeding stops). Their model suggests individuals could make a nonstop migration from the Intermountain West to overwintering areas in Mexico (> 2,500 km; see Nature of Migration for details).

See also Glass and Watts 2009 for how energetics of breeding Ospreys differed with habitat in Chesapeake Bay, and how this correlated with breeding success and population growth in different regions (see Diet: Quantitative Analysis, above).

Metabolism and Temperature Regulation

Metabolism

Basal metabolic rate (BMR) in Ospreys has been calculated at 3.2 kcal/h/kg (13.4 kJ/h/kg; Wasser 1979 in Prevost 1982)—the highest relative to body mass of 12 raptor species studied by Wasser 1986.

In British Columbia, average energy assimilated from an average fish (black bullhead) at 2 sites in southeastern British Columbia has been estimated at 242 kJ (58 kcal; assuming 80% assimilation efficiency), and at wind speeds above 7 m/s (25.2 km/h), foraging is not energetically profitable (Machmer and Ydenberg 1990). At these same sites, energy content of various fish species captured ranged from 275 to 3,210 kJ/fish (66–768 kcal). Profitability of hunting bouts was 0.91 kJ/s (0.22 kcal/s) at a lake, where weighted average energy content/fish (for all prey species) was 1,629 kJ (390 kcal) and 0.23 kJ/s (0.055 kcal/s) at a nearby marsh, where energy/fish was only 472 kJ (112 kcal; Steeger et al. 1992).

Temperature Regulation

Three Ospreys from Florida had a mean body temperature of 39°C and showed a high thermal conductance, 172% of the value predicted for a bird of its mass (based on data for 12 raptor species), as would be expected for a bird with a high metabolic rate (see above) in a warm climate (Wasser 1986). Lower limit to the thermoneutral zone for these Ospreys was 22.6°C (Wasser 1986), with upper limit probably about 40°C (J. S. Wasser, personal communication).

Drinking, Pellet-Casting and Defecation

Water is probably adequately supplied in the flesh of fish eaten, although there are reports of adults drinking on hot days (S. Postupalsky in Vana-Miller 1987).

Individuals regurgitate indigestible bones and scales in a pellet, as is typical of birds of prey, but these pellets are small and produced infrequently, suggesting that much of consumed prey is digested and absorbed through the gut. The small intestine is narrow and long (1.96 m in a female from North Carolina; ROB; see also Stone et al. 1978).

Defecation, typical of the accipitrids, is projectile—birds bend forward, lift their tails, and shoot combined fecal and urinary wastes a considerable distance behind them.

Recommended Citation

Bierregaard, Richard O., Alan F. Poole, Mark S. Martell, Peter Pyle and Michael A. Patten. 2016. Osprey (Pandion haliaetus), version 2.0. In The Birds of North America (P. G. Rodewald, editor). Cornell Lab of Ornithology, Ithaca, New York, USA. https://doi.org/10.2173/bna.683