Citations to the Previous Post

I could not find the McKinney paper. Here's the Pierotti and Annett:

IN DIFFERENT SOCIAL CATEGORIES. The Condor 96 (3): 590-599.

For more information about Mallard aggression, consult the Mallard BIRDS OF NORTH AMERICA life history.

Mallard Homicide

In 1991-2, at Lake Muhlenberg, a pond in Cedar Beach Park, a suburban park in western Allentown, PA, USA, the public was feeding the Mallards so much bread that the pond was full of ducks. Pretty soon in 1991 birds were ganging up on one another and "space and chasing" each other aggressively (term by late Dr. Frank McKinney) to shore where the back of the neck would be snapped by an aggressor bill, causing death. A classic case of "density-dependent" (term in ecology) mortality, it reminds me of too many molecules in one space or too many balls on a pool table, the more there are then more friction there is. There was an island in the middle of the pond, and workers were using it as a cemetery!
Mostly, if not invariably, domestic x wild hybrids were the victims. This may have happened in part, too, to save up resources (food) for non-sterile pure breeds to guarantee energy for reproduction. But I saw limited direct evidence of courtship and copulating, though some, despite all this happening in the spring.
It is interesting to note that Pierotti and Annett (1994) found social class (age, sex, and territorial status) asymmetries in success in territorial aggression between nesting Western Gulls in a packed breeding colony. I did not have banding privileges, and it did not occur to me to try to track individuals by their unique plumages and other markings. But Pierotti and Annett observed discrete social behavioral patterns according to status in the flock, which determined success, i.e. whether the territory holder succeeded in holding off the attacker.
It was another space saturation situation. Established males were able to hold off almost all attackers. Unestablished males came second. Established females were able to hold off all except for adult males. Then came unestablished females.
Who knows, maybe the same dynamics were occurring at Lake Muhlenberg. One needs a pond and wild Mallards, feed them ad libitum, in the breeding season, and take copious notes!
Happy holidays, everyone!

Misc. Bird Study

How many of us ever got to know a wild animal? I do not mean merely to meet with one once or twice…but to really know it for a long time…and to get an insight into life and history.

- Earnest Thompson Seton in THE AMERICAN CROW AND THE COMMON RAVEN by Lawrence Kilham


Grant Stevenson
Director and Amateur Ornithologist
GreenSpace Unlimited
946 Seneca Street, Suite 11
Bethlehem, PA 18015
Phn 610-867-2862
Fax 610-866-6234; call first

Stevenson -2- Avian Behavioral Ecology


The study of animal behavior, or ethology, is called by the British “behavioral ecology”, a term I prefer personally because I believe it describes it best and is all-encompassing on
the subject. For instance, behavioral ecology also studies human behavior, though not often. It also is not afraid of biological theory (hence the journal, The Journal of Biological Theory). I have had the privilege of belonging to Oxford’s The International Society for Behavioral Ecology (ISBE), which publishes the good journal BEHAVIORAL ECOLOGY. Behavioral Ecology is not interested in “how”, morphological and physiological questions, but “why”, evolutionary adaptive questions. What is the selective reason for this behavior? How does it help the bird “cope” (adapt) to its environment? As you can see, behavioral ecology has helped the sciences of psychology and neuropsychiatry endlessly. The comparative method is widespread in organismal behavioral science. It allows scientists and amateurs to compare different species from different families, orders, and even classes (mammals, birds: higher vertebrates) if the evolutionary reason for the two similar behaviors is the same. Originally used by morphologists, Konrad Lorenz of Germany, one of two fathers of animal behavior, with Niko Tinbergen of Norway in mid-last century, applied it to the behavior of waterfowl and gulls, respectively. Another method is contentious among professional ornithologists: whether to "tame" your subject species, say with whole kernel corn with American Crows (Corvus brachyrhynchos), so they will act close and natural around you, or whether such taming causes them to act in unnatural ways. Many raptor biologists cite studying manned raptors in falconry, with its training, for hunting data, as artificial. I personally do not know the answer to the taming issue. It may depend on what species, what journal, how you write it and account for possible anthropomorphic effects, if you can account for them all, and whether the species has the intelligence to be tamed in the first place (more on cognitivity in birds later- see crow section).

Stevenson -3- Avian Behavioral Ecology

For further reading on behavioral ecology, start with BEHAVIOURAL ECOLOGY: AN EVOLUTIONARY APPROACH by John R. Krebs and Nicholas B. Davies. Then read ANIMAL BEHAVIOR: AN EVOLOUTIONARY APPROACH by
John Alcock. These are the best overviews. The Alcock book is more readable and palatable to the birder, but Krebs and Davies wrote BEHAVIOURAL ECOLOGY: AN INTRODUCTION for that purpose, too. For an understanding of animal signals, such as bird vocalizations, see THE BEHAVIOR OF COMMUNICATING: EA ETHOLOGICAL APPROACH by W. John Smith, the doctoral advisor at The University of Pennsylvania of Dr. Robert Ricklefs, the foremost avian ecologist in the United States. If you want an understanding of bird ecology, I suggest AVIAN ECOLOGY by Christopher Perrins and T.R. Birkhead. Dr. Perrins is the current Director of the Edward Grey Institute of Field Ornithology at Oxford. This book is quite understandable, and affordable, at For you closet ornithologists, try THE ECONOMY OF NATURE by Dr. Ricklefs. AVIAN ECOLOGY is more oriented toward field avian ecology, but this book delves into depth more what every serious student should know. (Bob Ricklefs and Sir John Krebs are very interested in helping the amateur. I will ask them if they can help you via email once I get five names- via email- no more, and if they are not too busy, they can converse with you and preview your papers prior to submittal.) Do not, I repeat, do not buy these books unless you are particularly flush and can afford it. If you can afford used textbooks, try Otherwise, I always get them through Inter-library Loan from my public library and take notes and take down the
Stevenson -4- Avian Behavioral Ecology

citation. Simple as that: all I have to pay for is the minimal ILL fee. The general rule of thumb regarding textbooks is of two schools: one, newest editions have the most up to
date information, such as in biology, and two: subsequent editions don’t offer much m
information but, with the permissions of the authors, publishing companies make more business in a hard business by putting out more-and-more editions, like in statistics texts. It is subject-dependent, and up to the reader/user. Also, I suggest ON AGGRESSION, KING SOLOMON’S RING, and [book on ethology and the Greylag Goose] by Konrad Lorenz and THE CURIOUS NATURALIST and THE HERRING GULL’S WORLD by Niko Tinbergen. There are other important books by these two, and papers, in the textbooks’ bibliographies. But some of their material is out-dated. For an example, call The University of Oxford Press in the U.S. and request free sample of BEHAVIORAL ECOLOGY journal at 1-800-852-7323 ( If you have the funds, a student membership to the ISBE is $38; a regular one is $65. I highly recommend Donald Stokes’s A GUIDE TO BIRD BEHAVIOR, VOLUME 1, of all common species; though some subsequent scientific published papers have altered some of the book’s information, much of it still holds true. Stokes was the first to write an entire book of avian behavior for popular consumption, and ILL can find it in public libraries and. As you know, the scientific process means it is constantly being rewritten: Stokes was the first compendium that updated the classics since Catesby, Bartram, Audubon, Wilson, and the 19th and 20th century classics like Ridgeway, Coues, Bendire, Baird, Cooper, Chapman, Grinnell,

Stevenson -5- Avian Behavioral Ecology

Griscom, Bent, Sutton, Griscom, Heinrich, Davies, Krebs, etc., in readable, palatable form for the public.
For a partial, scientific, short course-outline of ethological concepts and theory, see Appendix I. It may behoove you to take an undergraduate course in ornithology. Stephen Kress's out-of-print book THE AUDUBON SOCIETY HANDBOOK FOR BIRDERS has such a list of colleges and courses in the back (see libraries or Harvest Books website). Muhlenberg College has an ornithology course for biology majors during the day and a non-major BIOLOGY OF BIRDS course in the evening adult Wescoe School. Adults can take for credit or audit either. Cornell University offers a BIRD BIOLOGY course through the computer through its Cornell Lab of Ornithology. In order to take it, you must pay for it or get a full scholarship through the Lab. Or you can buy their book HANDBOOK OF BIRD BIOLOGY for $99.50 (65 pounds) from Princeton Universty Press (



Optimal foraging is a behavioral ecological term defined by Robert E. Ricklefs (1993, The economics of nature, W.H. Freeman, New York.) as “a set of rules, including breadth of diet, by which organisms maximize food intake per unit time or minimize the time needed to meet their food requirements; risk of predation may also enter the equation for optimal foraging”. Optimal giving up time (GUT) is “the time that an organism should remain within a patch of resources before moving onto the next in order to maximize its rate of food intake”. Optimization of foraging is discussed in detail by Krebs (1984, Behavioural ecology: an evolutionary approach, Sinauer Associates, Inc., Sunderland, MA, for newer editions, and Blackwell Scientific Publications, Oxford, for earlier editions) and Ricklefs (1993).

Stevenson -6- Avian Behavioral Ecology

Anti-predator behavior is avoidance behavior toward predators of all classes of animals based on species size: small species tend to forage, roost, and breed near or in foliage, middle-sized birds like American Crows (Corvus brachyrhynchos) tend to go to woody
foliage and also outmaneuver avian predators in flight, and larger birds like Common Ravens (Corvus corax) and gulls outmaneuver and the ravens will turn on aerial predators. There are exceptions to this observation for a lot of species. Perhaps the most exemplary is the White-throated Swift (Aeronautes saxatalis), which even escape the Peregrine Falcon (Falco peregrinus) out west (Lima, Steven L. 1993, Ecological and evolutionary perspectives on escape from predatory attack: a survey of North American birds, Wilson Bull. 105(1): 1-47.).

Part 1. Foraging Patterns

I observed American Robins (Turdus migratorius), n100, foraging for earthworms (Oligochaeta: Lumbricdae) on the suburban lawns of Cedar Beach Park in Allentown, Lehigh County, eastern-central Pennsylvania (40.5968N x –75.5124W), in 1992, in a small flock with Common Grackles (Quiscalus quiscula). Birds tended not to forage straighter and in shorter bouts after a successful encounter with prey (Mood’s Median Test, N=1, 2= 0.1, p= 0.05, df= 1). Birds also tended to turn less acute angles after a successful
Stevenson -7- Avian Behavioral Ecology

probe (median= 140; N=1, 2= 628.4, df= 1, p= 0.05). The mean angle degrees after a successful run was 134 (SE13, cv= 40%). The mean angle degrees after not catching a worm was also 134 (SE13, cv= 38%). The mean angle after a successful run was 141.7 (n= 16, SE11.7, cv= 33%). The mean angle between unsuccessful runs was 140.6 (n= 16, SE12.3, cv= 36%). Not all robins do this behavior (Sign Test, z= 10, p>
0.09, N.S. (non-significant)), but the observation was not unique (z= 0, p= 0.01). However, Sign Tests are low-powered statistically.
My next robin optimal foraging project at the following site (in Part 2) will involve this spring observing GUT with a stopwatch with microseconds, measuring time of foraging on micropatches of lawn before they give up and move between patches in four categories, individuals, pair-bonding pairs, small flocks ( 25 individuals), and large flocks ( 25 individuals), either due to predator presence or searching for more food. Summer breeding foraging dynamics may be different either in the incubation, nestling
or fledgling stage. Also, worm catch (after detection) and beak handling times in microseconds will be recorded. At least thirty samples each of these two variables will be recorded: a Spearman’s R will be done if the two samples are even in number, a Mann-Whitney U if uneven. Seed handling time in finches (Darwin’s Finches; Abbot, I., et al, 1975, Seed selection and handling ability of four species of Darwin’s Finches, Condor 77: 332-335; Grant, P.R., 1986, Ecology and evolution of Darwin’s Finches, Princeton University Press, Princeton, New Jersey.) and North American selected Fringillidae and Emberizidae finches (Willson, M.F., 1971, Seed selection in some North American
Stevenson -8- Avian Behavioral Ecology

finches, Condor 73: 415-429.). Dr. Willson examined fruit choices by robins (1994, Fruit choices by captive American Robins, Condor 96(2): 494-502.), but an average worm handling time has not been calculated, to the best of my knowledge. The average earthworm weighs about [0.2g] and is not “chewed” buy the upper and lower mandibles,
but the head is tilted back and the item swallowed whole, thus a thin beak (shallow depth). A rule to all evolutionary biology is: “form fits function”.

Part 2. Avoiding Predation

Anti-predator behavior is staying next to foliage while ground foraging, say J.O. Oyugi and J.S. Brown (2003, Giving up densities and habitat preferences of European Starlings and American Robins, Condor 105(1): 130-135.). But Lima (1993) points out they
often seen, including by me, singularly to large flocks in the middle of lawns. Why? Evolution should have an answer. I observed foraging spring and fall flocks since 1994 at the grounds of the Allentown State Hospital (ASH), Allentown, Lehigh County, Pennsylvania (40.6151N x –75.4293W), where, because I am on the Board of Trustees, the administration and security has so graciously allowed me to use it as a study site (Acknowledgements: Gregory Smith, President and CEO, and Ms. Tiffany Hudock, Administrative Assistant to Mr. Smith). The robin alarm note is a species-specific signal that is barely audible to the human ear (See: Caldwell, G.S. 1986, Predation as a selective force on foraging herons: effects of plumage color and flocking, The Auk 103: 494-505.).
Stevenson -9- Avian Behavioral Ecology

So I will purchase a Radio Shack or Sears sensitive pocket cassette recorder, or go on Ebay and see if they have plastic parabolic reflectors attached to amplified microphones attached to sensitive playback pocket recorders capable of making and playing continuous loop tapes or CDs. I saw flocks get up and shift places, a kind of “following-the-leader” to new found food patch or in response to human movement, but when they flew completely away, they seemed to be often with American Crows or European Starlings (Sturnus vulgaris), and
possibly Common Grackles and Red-winged Blackbirds (Agelaius phoeniceus), and even more remotely so, Brewer’s (Euphagus cyanocephalus) and Rusty (Euphagus carolinus) Blackbirds. (There was the chance for a rare Emberizine or House Sparrow (Plocidae: Passer domesticus), but I only remember a Grasshopper Sparrow (Ammadramus savannarum)-call in a field full of Red-wings, that was a filled-in wetland, in another part of the property. Please see that ASH is in the suburban buffer zone between Allentown and Bethlehem. I may start a spring hawkwatch there because it overlooks the Lehigh River and I’ve observed quite a bit of raptor migration activity from there (fortunately
the governor and state senate appointed me to the board there twice, making it Grant’s little private bird preserve with Mr. Smith’s kind permission.) Were they responding to cues, visual or auditory, from the other species? Or could the warn themselves? If so, was it with visual or auditory signals, or both? How did they react towards an avian or mammalian predator? Did they ignore them for a time? How long? (Predator Presence

Stevenson -10- Avian Behavioral Ecology

Tolerance (PPT)- my term- defined by time of ignorance, per separate taxa of predator, including hominid).


Part 1. Optimal Cooperative Feeding

I define optimal cooperative feeding in American Crows as the mutual use of sentinels as predator guards while others feed below, then after awhile they switch off, and the sentinels feed. It is optimal because all individuals get to feed while not worrying about “looking up” for predators, optimizing energy intake. European Starlings do it (), and an observer of Canada Geese (Branta canadensis) told me he feels a drake always watches for predators in a flock at Cedar Beach: as he gets closer, it honks loudly and repeatedly and the flock moves away from the intruder.
I have observed many instances of sentineling, but because I was going somewhere, I could not stick around for the switch-off. Sentineling in corvids is, though not well, documented. Lawrence Kilham observed this in only small groups (1989, The American Crow and Common Raven, Texas A&M University Press, College Station, TX.), but I have seen this behavior in mass winter roosts up to 50,000 birds (winter roosts have been observed up to 200,000 birds documented, they may go larger according to the carrying capacity of the habitat), the more birds on the ground, the more sentinels in trees. Winter roosts travel up to 81 kilometers a day in search of food (Terres, J.K., 1980, The Audubon encyclopedia of North American birds, Alfred A. Knopf, New York.). This is because Optimal Foraging Theory says once at a foraging habitat patch, it is the Law of Diminishing Returns. Eventually, it is worth the energy expenditure to travel elsewhere.

I have seen cooperative feeding in crows personally only once according to my mutualism definition because of my itinerant schedule. It occurred at a street in front of
2/21/06 -10- Common Bird Behavior

Cedar Crest College, on the southern border of Cedar Beach Park in Allentown. It involved only two crows, possibly cooperatively breeding yearlings from a nearby nest attended to by the parental pair. Both took turns sentineling and and feeding in the road for ten minutes per bout, sentineling from approximately the same distance and height, feeding on what I hypothesize to be road-cracked acorns. American Crows () and Japanese Jungle Crows (Corvus macrorhynchos japonensis) in Tokyo () have been shown to use automobiles as nutcrackers, as tools, including American Crows with walnuts (Juglans spps.; Black Walnut Juglans nigra). A Sign Test calculated that the probability of all American Crows cooperatively feed, by my definition and sample, is 99%, very significant (z= 1.41, p= 0.01).

Off-spring Paper on Raptors



I define “intended offspring” as either data for clutch size or fledgling size per each nest, successful or not, averaged here from samples in the literature and nest cards.
Knowing intended offspring of all falconiforms for this analysis was statistically unnecessary according to the opinion of a professional statistician this amateur consulted (Root pers. com.). I used study samples from nine species in The Birds of North America life histories. Many measures of spread (standard deviations or errors) were left out of BNA samples. It is necessary to know how data is distributed to be useful. So I assumed that BNA editors were unable to provide spread for all their data. That way I was able to obtain a "sizable" amount of samples. An even sample was deemed unnecessary by the consultant because it would "even out". It seemed to. A large sample is unnecessary because the relationship of raptor mass to intended offspring is generally consistent throughout the order, and in all birds, according to leading definitions of K and r-selection. I used survivorship curve definitions of K and r-selection from Klem (pers. com.), Horn and Rubenstein (1984, in Krebs, J.R., and Davies, N.B., Behavioural ecology: an evolutionary approach, Second Ed., Blackwell Scientific Publications, Oxford, U.K.), Pianka (1970, On r- and K-selection, The American Naturalist, June: 592-597), and Newton (1979, The population ecology of raptors, Buteo Books, Vermillion SD U.S.A). Included in all definitions were, for K-selection, large size and few young, and for r-selection, small size and many young. My hypothesis was the index between K and r-selection in raptors is a number of about three intended offspring.
From encyclopedias and handbooks, I calculated average brood size for 33 North American species to be 1.5 (SE 0.05) based on a 154 d average breeding period.
I arbitrarily selected the species means because in the final analysis the selection mean should not differ too much from how the species means were selected, or if all diurnal raptor species means (Root pers. comm.). I took "the mean of the means" because even though an even, gradual right-climb in the plotted data, it wasn't abrupt enough to use medians. The means were Golden Eagle (/x= 0.3, nest cards), Northern Goshawk (/x= 1.8, Reynolds et al 1994, Nest productivity, fidelity, and spacing of northern goshawks in northern Arizona, Stud. Avian Biol. 16: 106-133), Red-shouldered Hawk (/x= 2.7, Wiley, J.W. 1995, The nesting and reproductive success of Red-tailed Hawks and Red-shouldered Hawks in Orange County, California, 1973, Condor 77: 133-139), Cooper's Hawk (/x= 2.8, Craighead, J.J., and F.C. Craighead 1956, Hawks, owls, and wildlife, Stackpole Co. and Wildlife Management Institute, New York), Harris' Hawk (/x= 3, Bednarz, J.C. 1995, Harris' Hawk (Parabuteo uncinctus), The Birds of North America, No. 146 (A. Poole and F. Gill, eds.), The Academy of Natural Science, Philadelphia, PA, and The American Ornithologists Union, Washington, D.C.), White-tailed Kite (/x= 3.2, Dixon, J.B. et al 1957, Natural history of the White-tailed Kite in San Diego County, California, The Condor 59: 156-165), Ferruginous Hawk (/x= 3.7, Smith, D.G., et al 1981, Relationships between jackrabbit abundance and Ferruginous Hawk reproduction, The Condor 83: 52-56), Peregrine Falcon (/x= 3.7, White, C.M., et al 2002, Peregrine Falcon (Falco peregrinus), The Birds of North America Online (A. Poole, Ed.) Ithaca: Cornell Laboratory of Ornithology; Retrieved from The Birds of North America Online database:, Sharp-shinned Hawk (/x= 4.5, Bilstein, K.L., and K. Meyer 2000, Sharp-shinned Hawk (Accipiter striatus). In The Birds of North America, No. 484 (A. Poole and F. Gill, eds.). The Birds of North America, Inc., Philadelphia, PA.), and American Kestrel (/x= 4.6, Smallwood, J.A., and D.M. Bird 2002, American Kestrel (Falco sparverius). In The Birds of North America, No. 602 (A. Poole and F. Gill, eds.). The Birds of North America, Inc., Philadelphia, PA.). The mean is 3.03 (n= 10, /x= 3.03, SE+- 0.40). The mean is not significantly variant from the estimate (hypothesis). Because of the low-powered, random sample, a type II error may have been committed. My estimate was the number of intended off-spring between r and k-selection is a clutch of approximately +/- 3 eggs.
Various teachers helped me with this calculation, including R. Root, C. Farmer, J. Lowe for nest cards, J. Schmutz, and A. Kemp. -Grant Stevenson, Open Space

(no subject)


The winter coming is the time for wax-eating yellow-rumps in Christmas Bird Counts. But in an 1992 paper (Place and Stiles 109:(2): 334-345), yellow-rumps and Pine Warblers both eat fruit like poison ivy and bayberry and waxy fruit (Myricia). Yellow-rumps have always migrated, along with phoebes, so late, that most birders now consider them all-winter possibilities, as the research, and CBC's demonstrate. One study (Wilz and Giampa 1978) studied them at Presque Isle and asked: why do these species overwinter so far north? They concluded, finding a mostly bayberry diet, the same thing Place and Stiles did, but added spider eggs. In both studies, Tree Swallows and flickers were mentioned as wax eaters which migrated, I assume, late.Going back to the archive of PB at Lehigh University, counts and less formal sightings have definitely fit these truisms.
I remember my first CBC finding a catbird. Root (1988) published in the journal Biogeography and also in Ecology how energy metabolism (energetics) and the environmental factors of elevation, frost-free periods, latitude, vegetation, mean annual precipitation, general humidity, and minimum January temperature brought surprising lingerers at that time of such as kinglets, Sedge, House and Marsh Wrens, Brown Thrasher, and both vultures. For example, ambient temperature and elevation tend to affect the winter distrabution of Bonapartes Gulls the most, placing them on large lakes that tend not to freeze over. Now concentrating on the effects of global warming on bird species distributions (, Dr. Terry Root has found that ducks that use prairie potholes, such as some species which the perhaps mostly first year individuals “loop” migrate back in the spring via PA, if non-raptorial (diurnal) birds do so (from Bildstein 2006 in respect to diurnal raptors), are threatened in North America and Australia due to drying of the landscape.

Hairies and Downies


Grant Stevenson 1, 2

ABSTRACT.- Birdwatchers learn that to find Hairy Woodpeckers (Picoides villosus) it is getting easier since the 1992 Audubon designation of a Species of Special Concern, due to private farm reversion to woods and the maturing of exurban woods in parkland and woodland near water. Downy Woodpeckers still predominanently inhabit dryer secondary successional woods also, but denser with less mature stems (shorter trees with smaller DBH circumferences). The issue of better woodpecker management as cavity nester conservation is discussed, especially the need for de-emphasizing even-aged timber management.

Key Words: Downy Woodpecker (Picoides pubescens), Hairy Woodpecker (Picoides villosus), nest cards, cavity nesters, even-aged timber management.

Coop behavior in General

Cooperative behavior: what makes it so, and what makes it simply a blip in the natural history spectrum?- Cooperative breeding and what makes it so is definitive, or is it? Skutch (1987) cited many instances where the fact that cooperative breeding, and kin selection, occurred, or did it? As long as some genetic co-transference occurs down, technically there is cooperation. A cooperative animal operation by definition should contain as much relatedness between individuals as possible, though technically mechanical operations devoid of such inclusiveness are possible, especially of the mutual kind, like American White Pelicans schooling fish (Cottam, C. et al 1942), American Crows feeding on car-crushed acorns (my one observation/ idea), and even broadwings seeing prey cooperatively while in flock, and of course Harris' Hawks cooperatively hunting (more like mammals pack-hunting). Animals exploit the presence and actions of others, but the passing down of genotypes does not occur.
There may be related individuals within a flock, but "wholeness" is a prerequisite for cooperation. Chimney Swift helpers were even termed only as "visitors", in a sense "floating helpers" (Dexter 1995). No inclusiveness occurred, no helping to the point of the passing of related genotypes. Visitors had the least amount of relatedness of many cooperative species. Evolution bumped on the parking lot slow bumper.
Perhaps this is not about relatedness, like Emlem's bee eaters, but mutual fitness, and the almost pure altruism necessary to bring it out, and evolutionary bizarreness?
I have no proof, just speculation, a one species, which makes these theoretical meanderings doubtful, and highly. It is clear to me, without scientific proof, that Dexter at least sometimes separated "visitors" from "helpers", but more literally than scientifically. Indeed, "visitors" and "helpers-at-the-nest" have been reported for a number of species (Woolfenden 1976).
I digressed wholly and apologize. I am a fifteen-year amateur, and should be spending my time with natural history and field observation, not out of my league with theory. Yet one can learn from flopping around inside it. I hope the audience was patient, and may even reply so I can learn a lesson or two.- GRANT STEVENSON, Open Space
Consultants, 946 Seneca Street, Suite 11, Bethlehem, PA 18015 (email:


COTTHAM, C. et al. 1942. The cooperative feeding of White Pelicans. Auk 59(3): 444-445.

DEXTER, R.W. 1992. Sociality of Chimney Swifts (Chaetura pelagica) nesting in a colony.
North American Bird Bander 17(2): 61-64.

SKUTCH, A.F. 1987. Helpers at birds' nests: a worldwide survey of cooperative breeding and related behavior. University of Iowa Press, Iowa City.


Coop breeding in Corvidae


Corvids- like us- are social. Even though there are ornithological papers saying that American Crows use cars as nutcrackers and do not, they are cooperative feeders, using sentinels too look out as others feed on the ground, and as cooperative breeders, territory members share information to show each other where the grub is. Common Ravens do the same, as perhaps other raven and crow species.
But there are other north American corvids that cooperatively breed, maybe feed, and “flock”, a social behavior which enables social protection and more eyes to see a limited or ecologically constrained resource like food or potential nest sites. Like in ravens, they are organized by a “peck” dominated male and female, sometimes in a hierarchy, though in ravens it is not progressive. At a carrion “bonanza”, the two birds have the other adults and juveniles under them and they feed when they want to eat.

Brown Jay

Green Jay

Florida Scrub Jay

Pinyon Jay

Mexican Jay

Tufted Jay

Northwestern Crow- very few helpers per nest

These species are also notorious flockers. Dr. Stephen T. Emlen of Cornell examined 112 bird species and 63 mammal species and found that 96% of avian species and 90% of mammal species demonstrate cooperative breeding. Cooperative breeding, he said, is primarily restricted to familial societies.
He found that 88% of the birds and 95% of the mammals are cooperative breeders living in multigenerational family groups.

Blue Jays.- Are hard to keep up with enough to indicate coop anything, though breeding pairs can hold onto territories all year round. There was one MS thesis indicating observance of helping, but it did not go anywhere.
Cooperative breeding is defined as pairs helped by familials such as previous off-spring while passing on only 50% of their genes, with the hope of gaining the parental territory to breed in in the future upon the deaths of the dominant parents. Cooperative feeding, named after Eurasian and American White Pelicans learned to coral fish using a cooperative closing circle (and peripheral single feeders have more luck!), can mean a lot in corvids, like flocking daily winter night (I.e. crows) and day (I.e. Pinyon Jays) roosts and the use of sentinels (which starlings and Canada Geese do, too) and is defined as comensually (one side profits, the hunted does not, as opposed to mutualism and parasitism). Sociality is expressed in many behaviors such as flocking.

American Crow Behavior


Dear Corvi's:

My handwriting caused the Chronicle to inadvertently spell my handle incorrectly: it's C. frugivorus Bartram. However, I thought since of a better solution. From now on I'm Corvi 2.58 (I'll try another number if already taken.). Unless you are a professional or amateur statistician, the number has no significance. It's the z distribution number that indicates p= 0.05, often times the minimal acceptable probability (95%) for a behavior, number, etc., but in ecology less significant probabilities are accepted because of field realities (Wiens, J.A., The ecology of bird communities,).
Our crow literature, whether a good library book or the published scientific literature, says that American Crows (Corvus brachyrhynchos) and Jungle Crows (Corvus macrorhynchos), and perhaps other species, like urban human refuse most as a food source, then invertebrates, including those in urban and suburban lawns. Even though both are originally forest species, they have hyperadapted to the smorgasbords left by humans and the breeding predator safety of their neighborhoods. Crow cultural innovation, because Corvidae brains have one of the highest brain masses to body mass ratios of all birds (Reckless, R.E., Wilson Bulletin 116(2): 119-133 (2004)), has caused a commensally (one species gains while the other doesn't) symbiotic feeding relationship between crows, other corvids, and humans. The Gray Jay since Thoreau's time and earlier has been known as "the picnic and campsite robber", often quickly snatching food like bacon right out of hands when humans are not looking, which takes timing and learned skill. They also have learned to be a passenger on the bow tips of canoes.
Making the garbage more sanitary will not necessarily decrease roosts because crow culture is fast to innovate toward another hominid food source. Killing members of a roost will definitely not work because of supply and demand, ecology, and population demography rules. In other words, over the long-term, healthy remaining crows will take advantage of the more available food and other resources and reproduce more.

Corvi #2.58 -2- Letter: Corvus Smarts

Lastly, I am investigating the hypothesis that American Crows display occasionally not only cooperative breeding, but COOPERATING FEEDING. Selective feeding already has been documented. Crows, for example, as proven by the eight year old son of John Marzluff, prominent world crow biologist at the University of Washington, readily distinguish McDonald's fries in a McDonald's bag from fried potatoes made at home in an unmarked bag, only a few meters away, preferring Mickey Dee's fat-soaked fries that a substantial portion of us like so much. I define cooperative feeding in crows as "mutual". In other words,
when a sentinel comes down from a perch to feed in the group, at least one from the ground ascends to replace it, senteneling "in exchange". Feed corn, or cracked corn from the grocery store, will be used, maybe even a dead deer in a local refuge. I have a spot right outside my window all year long in Bethlehem if the police cooperate. I am asking any and all Corvi's to contribute observations to the project, however opportunistic, at the below address. All that needs to be said is "coop. feeding observed, X no. of times [even if once], in [urban, suburban, exurban, rural] setting" and your true name if you wish to be acknowledged in the journal article, on a postcard, if you wish. Or you can contact me at any of the below unless you wish to remain anonymous. Thank you very much!!

Corvi #2.58
Director and 14-Yr. Amateur Ornithologist
Open Space Consultants
946 Seneca Street, Suite 11
Bethlehem, PA 18015
Phn 610-867-2862
Fax 610-866-6234, call first
Amateur ornithology research URL, PAHawkowl:

The Grinnell Journal

Arrogant Amateur: Statistics and 17 Years of The Grinnell System As A Long-Term Study

Grant Stevenson

The Joseph Grinnell style avian daily and species journal has many applications, and contrary to popular professional belief lends itself to rigorous statistical data analysis. The goal here is to give one example of a species account from the daily birding entries, for the American Crow (Corvus brachrychos) and analyze them for time-series analysis and unique center and spread techniques non-traditional in ornithology: the stem plot and quantile analysis. Simplification of technique is emphasized, including the advantage of simple descriptive statistics such as frequency polygons. One of my main theses is that the most simple presentation of data is preferred over sophisticated, but unnecessary methods. Finally, I prove fairly that a lot of professional ornithologists do not apply correct analysis (Moore and McCabe 2003), as a lot of professional statisticians do not know the limits, most variables, and field reality of biostatistics (Zar 1997; Wiens 1989). For example of the latter, Wiens (1989) states that in field avian community ecology there are so many variables that a p-value of <0.15 is acceptable. Applied to long-term data bases such as more than ten years of journaling of a variety of different habitats and species, which for one person is significant, I use my crow species account from 1995 to 2008 to illustrate what applications can be made, plus a word about the global warming value of the method, and how a hard copy is always preferrable in the long-term to websites and software, lest the system shuts down or brakes, possibly destrying your data forever. The Grinnell journal thus is a predessesor to eBird and Avisys, etc. Back tracking, only two variables are worthy of consideration, space and time (Wiens 1989), which is not as easy as thought in a census model, such as the all important local life history/nesting studies or local, weekly Resident Bird Counts. First though, I present how the Grinnell Method of natural history journaling is done.

History foundation.- Joseph Grinnell, not to be confused with the earlier personage of George Bird Grinnell of the Smithsonian Institution, a contemporary colleague of James Baird, was a professor in the University of California Museum of Vertebrates at Berkley in the early twentieth century, not to be confused with the current Western Foundation of Vertebrate Zoology. He, with ornithologists like J. V. Remsen, Sr., determined an ecological method to record natural history observations, from birds to botany. Trained as a mammal and avian morphological taxonomist, he realized the need for a standardized method of wildlife observation recording.

Example of Daily and Species Accounts.- Remsen, Jr. (1977), Herman (1986), and Kress () well describe simply how to do a Grinnell system of field notes. Carry a memo book always with you, writing the date and times, species lists within those times, and write in pencil because it is erasable and does not blurr in the rain. Write-in-the-Rain field books are an expensive, and not necessary, alternative. A simple surveyer's book is useful for more elaberate field projects.