A Survey of Ornithological Papers
by Chewy
A Dive into 30 Studies about Feathered Friends All Across the World
Whether you like it or not, birds are everywhere. Lighting up our audial neurons with their wide ranges of vocalizations everytime we step outside, they constantly remind us that there is a substantial world of life chugging along everyday. They inhabit the most urban concrete jungles as well as the most remote places on the globe. Some are year-round residents of one area for their whole life and some travel over 55,000 miles every year. Many of the papers that were collected in this survey had a theme in mind for their decision to be included: migration definitely being a big one, but also many other important facets of avian life like in ways of communication, sexual selection, social and mating systems, and overall conservation of species from anthropogenic influences on their ranges.
The papers are arranged by a picture of the study species and a brief summary of the respective contents of the paper, including a link to the study in full if you are interested in learning more about their results or the study design. Map points for each paper are directed toward the lab that the lead author worked in for the study.
If any species that was studied ends up piquing your interest, the following is a link to eBird's explore page which allows you to type in the common name of any species of bird and access a large database of year-round observations, vocalizations, and potentially weekly sightings in your area.
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1
American Crow Mask Recognition
Dr. Marzluff lead a team in the College of the Environment at the University of Washington to see the ability of C. branchyrhynchos to recognize a mask that banded 7-15 crows and their ability to see the masked individual in a crowd and to communicate such harsh feelings and sounds to other crows. They found that the crows were effectively able to utilize cultural learning to both recognize the specific mask that banded the birds, even in a heavy crowd or with other types of masks in the mix as well. Other crows that were not a part of the original banded bunch also joined in to the scolding to the banding masked individual. This scolding behavior was seen to last 2.7 years, which shows the extreme lasting effect that such transmission has on organisms, this scolding behavior and memory of organisms that harm or make the crows uncomfortable is more favorable, as those who are able to notice and avoid potential threats are able to survive long enough to reproduce. The crows were able to individually recognize the masked individuals and then culturally spread such information to other crows.
2
Red-winged Blackbird Anti-parasite Aggressiveness
Dr. Yasukawa of the Biology Lab at Beloit College searched the relationship between red-winged blackbirds, an acceptor species of parasitism, and brown-headed cowbirds. The study’s main component was testing the frontloaded antiparasite defense hypothesis (FPDH), which is a defense mechanism of acceptor species like these red-winged blackbirds to avoid parasitism by attacking parasites when they are around active nests in their territory. Yasukawa tested this hypothesis by using taxidermy models of northern cardinals, male brown-headed cowbirds (do not lay eggs), and female brown-headed cowbirds (lay eggs) along with their respective vocalizations for 5 minutes. FPDH was supported by the highest amount of taxidermy mount attacks by red-winged blackbirds being for the female brown-headed cowbird mount, and the least amount of attacks going to the northern cardinal. However, FPDH was not supported as the birds near the nests that responded the highest with aggressive behaviors were nests that were more frequently parasitized, as nests that were not parasitized before attacked fewer. This study shows that aggressive defense mechanisms can be in place to effectively deter parasitism at high volumes.
3
Satin Bowerbird Cognition Effects on Sexual Selection
Dr. Keagy in the Behavior, Ecology, Evolution and Systematics Lab at the University of Maryland tested relative cognitive ability via solving problems that directly involve their mating process. This was done by testing them in challenges that affected the surroundings of their bowers to be without any red objects due to their inherent disliking of the color in favor of blues. His team created two different cognitive tests and then compared these to each male’s reproductive success in that year. The first test was the barrier test, done by putting red objects under a clear, but removable object like a lid or a cup and seeing if the male satin bowerbirds could remove it and thus the red objects. The next test was putting an unremovable red object around their bower, like an object anchored to the ground or even using red paint to see if they could effectively cover the red spot up to make it unnoticeable. After the tests were concluded, they determined that there was a positive correlation between these very specific sexual cognitive tests with their bowers and male reproductive success, as females selected for the males that did better on the cognitive tests.
4
Brown-headed Cowbird mafia style aggression
Dr. Hoover and Robinson jointly working in the Division of Conservation and Ecology at the University of Florida as well as the University of Illinois set out to figure out parasitic nest behaviors of the brown-headed cowbirds on prothonotary warblers to explain mafia type behaviors as well as farming behaviors in light of different availabilities and statuses of the nests. They found that when the warblers ejected the cowbird's egg, 56% of nests were depredated in a mafia style way, in which the cowbirds keep track of their egg and if it is missing in the nest than they destroy all of the host eggs in the nest. Additionally, they do this as well when they find a suitable nest but miss the correct opportunity to sync their egg laying with the hosts', in a behavior called farming. After these depredation events, cowbirds parasitized 85% of the host re-nests, showing their effectiveness after their murderous behaviors. The behaviors also cause less ejector females, as 60% of nests that ejected saw fewer host offspring than cowbird egg acceptor nests.
5
Anthropogenetic Effects Driving Kirtland's Warbler to near Extinction
Dr. Kepler and his team of Michigan natural resource and wildlife specialists examined the life history of the Kirtland's warbler, what went wrong in their range and what some managerial solutions could be to recovering their population. Now, despite this paper coming out in 1996, I feel like it does a great job in explaining the causes of their population distress that occurred in the 1960s-70s. Kirtland’s warblers have extremely specific nesting requirements to allow their young to successfully hatch and to make it the fledgling age: they must nest under young Jack Pines, young enough where they still have low hanging branches that reach near the ground to protect the warbler nests from parasites or predators. They also need a large open clearing in the area of their nest for them to be able to forage efficiently, with the opening needing to be many acres from roughly 30-40 acres needed per breeding pair to successfully raise their young. Anthropogenic factors that led to their populations hovering around 200 individuals for over a decade was due to the logging industry as well as the lack of natural burns or even controlled burns in the Jack Pine area. This was crucial in losing numerous square miles of Kirtland’s warbler nesting range, as Jack Pines depend on natural burns from dead brush accumulation on the forest floor to open their cones and allow more Jack Pines to grow. Additionally, these burns get rid of old growth Jack Pines, which are useless to the warblers as they do not have the low-lying branches. Finally, these anthropogenic factors of removing Jack Pines and not letting them reproduce led to warbler nests way more out in the open, allowing for brown-headed cowbirds to easily parasitize these nests and take over host warbler nests with their large offspring. All these factors were eventually overcome through the following human interventions: controlled burns, regenerated the Jack Pines in their natural range, logging older Jack Pines, and setting up brown-headed cowbirds to greatly reduce the parasitism rate on Kirtland's warbler nests. As a result, this species has risen from critically endangered to only near threatened with over 2,000 individuals now in the population.
6
Episodic Memory in Black-capped Chickadees
From the Zuckerman Mind Brain Behavior Institute at Columbia University, Dr. Chettih stuck a probe in the brain that very rudimentarily tracks hippocampus activity in black-capped chickadees. His team then gave each individual chickadee a bowl of seeds and a maze of caching and retrieval areas, where the chickadee would cache seeds in as many places as they could and then later retrieve the seeds around the time in the season when they could retrieve them from their cached locations. It is not uncommon for bird species that live year-round in areas that get cold snaps often engage in caching behaviors, as it is advantageous to save food for the tough and food-lacking times of the season in winter and early spring. To account for remembering their caching locations, species like black-capped chickadees show seasonal hippocampal growth during caching and retrieval seasons. Dr. Chettih found that the pattern of neuron firing in the hippocampus of chickadees is the exact same for one location in the event of caching at the location and then retrieving at the same location. This activity was likened to an individual barcode for specific locations, where interestingly enough locations next to each other did not share similar neuron firing activity thus different barcode “readings”.
7
Testing genetic or learned behavior in European Starling migration
Juvenile and adult european starlings were captured near the coast of the Netherlands and blaindly relocated southeast to Switzerland by Dr. Piersma and his team at the University of Groninigen's Institution of Life Sciences. They captured them before their fall migration to their wintering grounds in Great Britain to determine their migration pattern and thus their specific method of migration learning. They found that adults were able to course correct to the north significantly better than the juveniles, which mostly all stayed the horizontal western course that they would have taken if they were in the Netherlands. Thus, starling method of migration acquisition is initially genetic, with adaptive course correcting possible in adults that have migrated before.
8
Great Knot Migration Tolls
Dr. Battley of Griffith University in Queensland Australia studied great knots before their migration in Australia and after their migration on the coast of China. They calculated numerous factors like fat content, skin, and various organ sizes. In their lab of environmental studies, they determined that these great knots lost around 80% of fat mass, around half of their skin, and significant decreases in the size of their kidneys, liver, intestine, and pectoral muscles. This all led to an overall basal metabolic rate decrease of 46%, with the only major organs that were the least affected by their migration being the lungs and brain.
9
Use of public information for increased foraging efficiency in osprey
Dr. Greene at the Biology Lab at Princeton University inquired on the use of public information and prey species identification in osprey. By observing their behavior in departures when seeing other osprey return with no food versus ones that return with fish, they can determine in what direction food is abundant in as well as what species of fish was caught so they can distinguish between more easily attainable fish species. This use of public information by these ospreys shortens the amount of wasted time in prey retrieval as well as increases their efficiency in hunting and minimizes time away from the nest, especially important during breeding season with hatchlings to be cared for and brooded.
10
Tool Use in New Caledonian Crows
Dr. Bluff from the Zoology Lab at the University of Oxford wanted to track crow tool use in a non-laboratory setting away from any human inputs. Thus, he and his team set up motion video cameras at seven spots where New Caledonian crows have been seen to use sticks and leaves to fish out wood beetles that are in the roots and stems of decaying trees. Overall, 14 different crows visited the sites for a total of 317 times. In those 317 times, 150 of them were video evidence of New Caledonian crows using sticks or lead stems as tools for foraging. Additionally, in a direct survey of the “fishing” areas later, researchers found 193 specific tools that the crows left behind inserted in the decayed wood. This study is very significant as it shows practical ecological application for the larger cognitive ability of New Caledonian crows as well as how this application can increase fitness via ease of foraging ability by tool use.
11
Polygyny and Territory Preference in Red-Winged Blackbirds
Dr. Pribil's Biology lab at the University of Miami, Coral Gables tested the polygyny threshold model in which females see a higher fitness in mating with an already mated male due to access to resources or due to protection from predators. Pribil was interested in testing this polygyny in mated males with territories over water versus unmated males with territories on land. They found that despite the relative preference for RWBBs for unmated males, they significantly chose nests with mated males that include nests over the water versus unmated males.
12
Dark-eyed Junco differential sex migration
Dr. Ketterson and Nolan Jr. of the University of Indiana's Biological lab in Bloomington studied the different migration patterns of male and female dark-eyed juncos to their wintering grounds laterally across the United States. They determined that males were much more likely to migrate norther in the U.S, and females were more likely to migrate more southern. The main conclusion of this very drastic sexual dichotomy in movement behavior is climate, as females did not need to experience the harsher colds in the southern migration strategy while being able to find more food as well as having to deal with fewer male competitors., as they are subordinate to males and thus suffer in competition for food when in groups. However, these have costs, as thus females in more southern areas are further away from breeding grounds up north for the spring.
13
American Robin responses to brood parasitism
American robins describe how hormones can affect how an animal behaves in lieu of specific stimuli, for example by their corticosterone increase when under environmental pressures, like experiencing brood parasitism events by cowbirds. Dr. Turner at the Beckman Institute for Advanced Science and Technology sought to determine Amercian robin's responses to different sizes and colors of parasitized eggs in their nest as well as the latency in rejection with increased cort. She found that deep blue eggs were rejected immediately but at only a 65% rate while beige eggs were rejected 91% of the time but within 1 minute to 10 hours of latency. Finally, increased cort birds were significantly more likely to reject parasitized cowbird eggs than non-cort robins were.
14
Lesser Scaup and Ruddy Duck Penis Maturation
Dr. Brennan, the undisputed bird penis expert, and her lab of Organismal and Evolutionary Biology at the University of Massachusetts Amherst set out to determine how differences in the male competition levels of Ruddy Duck and the Lesser Scaup play a role in their penis maturation in the breeding season if male to female sex ratios are altered, as Lesser Scaup have intermediate male competition naturally while Ruddy Duck see very high rates of male/male competition. They found that with increased male/male competition, Lesser Scaup penis's grew while Ruddy Duck's overall decreased in length and was not fully mature for longer in the breeding season.
15
Indigo Bunting migratory restlessness
Dr. Wolfgang Wiltschko is a zoology professor at the University of Hamburg where their department of biology investigated in what direction indigo buntings would travel in a similar photoperiodic environment from early in the breeding season to the summer. They utilized the Elmen funnel to track which direction these birds took off from, with the marks being seen in the funnel from the migratory restlessness. They found that their migratory restlessness behaviors died down near the middle of June, while their oriental patterns toward their migratory end point in the beginning of the breeding season started to become less accurate around the end of May.
16
Alarm call dishonesty in communal Barn Swallows
Dr. Moller of the Department of Zoology at the University of Uppsala in Sweden set out to discover the trends in colonial versus solitary barn swallow alarm call usage during the breeding season. This all has to do with forms of fake communication that can occur to increase ones fitness, which in the barn swallow's case, increase their likelihood of their genes being present in their mate's clutch. In line with this reasoning, they found that colonial males used alarm calls whenever they returned to the nest and their mate was not at the nest, especially when a male was seen perched nearby previously. The rate of alarm call was significantly higher during the egg laying period due to the high fertility of the females, with solitary males not engaging in such fake use of alarm calls to make all the birds in the area fly and dart away.
17
House Finches and Good Genes Hypothesis
Dr. Hill at the Zoology and Wildlife Science Lab at Auburn University tested if there was any correlation between the redness of the plumage of house finches and their nutritional status and start of their molt. He and his team found that the amount of carotenoids in the male house finch diet in specific related greatly to their brightness level of their plumage, thus the females were able to select for the males that were the savviest in finding berries rich in these carotenoids to make their plumage brighter than other males. These more red and thus healthy males were selected at a higher rate by females than less-red or yellow males, showing evidence for the good genes hypothesis in which females select male traits that are correlative of high-fitness.
18
The evolution of Muscovy sexual conflict between male and female genitalia
Dr. Brennan strikes again with another deep dive into the evolution of duck genitalia, this time looking at how each co-evolved due to male sexual aggression toward females, causing selection to favor female vaginas to corkscrew in the opposite direction of the male penis as well as introducing vaginal cavities to store unwanted sperm. Her team in the Department of Ecology and Evolutionary Biology at Yale University noted the specific morphology and eversion properties of the drake penises, explaining how the antagonistic vaginal evolution occurred and how females that achieve ideal mate choice go about making copulation be as successful as possible through exposing her cloaca and relaxing cloacal muscles.
19
Cooperative mobbing in Red-wing Blackbirds based on reciprocal altruism
Dr. Oldendorf of Kellogg Biological Station at Michigan State University tested the idea of reciprocal altruism with red-wing blackbirds, seeing if the addition of a simulated crow predator in an adjacent territory would make RWBBs go to their aid or to let them fend for themselves depending if that same attacked bird helped or defected from aid in the past. They found that reciprocal altruism through tit-for-tat, mechanisms holds true in RWBB, as RWBB who defected received no aid and those who helped in the past received help mobbing adjacent nests. However, tests of by-product mutalism and kin selection were not found in RWBB.
20
Dark-eyed Junco Offspring Viability and Amount in Various Family Dynamics
Dr. Wolf from Indiana University's Biology Lab inquired on how female juncos who were without parental support spent their time and energy on their young versus female parents with male support. Her team at IU along with help from members of Mountain Lake Biological Station found that unaided females spent more time feeding their young, less time brooding, more time away from the nest, and would have less young in general than in biparental situations. They also found that both aided and unaided females had a cutoff age of their young as they approached fledging age where they would lower their feeding rate of their young to prioritize their own health and living requirements.
21
Splendid Fairy Wren Sexual Competition in Sperm Size
At the Biological Lab at the University of Turku, Dr. Calhim evaluated the intricacies of the physiological aspects and mechanisms of sexual selection in Splendid Fairy Wrens, a highly promiscuous species where over 95% of nests during breeding season has an offspring that was spawned from an extra-pair copulation. Due to their promiscuity level, males have extremely high amounts of sperm that are produced during copulation events, and in their study, males that have sperm with longer flagellum are the birds that have higher fitness in their population. This sexual competition is extremely intricate, occurring at the microscopic level in the female reproductive system. However, females can also aid in securing their mate choice as opposed to it only being up to the males with the fastest sperm, as they have cavities in their vaginas that allow them to store sperm selectively.
22
Eurasian oystercatchers and foraging decisions based on food size
Foraging strategies are extremely important to maximize the amount of food that can be acquired at the expense of energy exerted to get that food over an organism's life. Dr. Meire in the Laboratory of Animal Ecology, Zoogeography and Nature Conservation at the Ghent University set out to determine the optimal feeding strategy used by the Eurasian oystercatchers when feeding on mussels (Mytilus edulis), despite the distribution of the mussels being not particularly skewed in one specific size, the oystercatchers significantly preferred breaking open and eating mussels between 30 to 45 mm, as this optimal foraging strategy allowed them to get an ample amount of meat inside of the mussel without spending too much energy and time breaking open the larger mussels.
23
Parental input of siblicide and nest switching of Masked and Blue-footed Boobies
Dr. Lougheed in the Department of Biology Lab at Wake Forest University undertook an experiment to determine how swapping eggs of these two species of Boobies that have different parental care methods of offspring would affect chick survivorship. The masked boobies who always hatch two eggs and kill one of them still see high rates of siblicide, over 0.8 when they raised BFB eggs, while BFB parents raised masked boobie eggs with a slightly increased rate of offspring from BFB + BFB nests, at around 0.4. This finding shows the importance of how parental dynamics of only feeding one offspring in MB parents really matters in young survivorship as well as how this has evolved in MB offspring to push the other offspring out, even in occurrences of BFB parents.
24
By-product mutualism and reciprocity in Pied-billed Flycatchers
By-product mutualism differs from reciprocity as with the former there is not temptation to cheat and not help your neighbors as cooperation benefits you as well as the interests of your neighbors, while in reciprocity there can be benefits to staying out of your neighbors business. Dr. Krama at the Biology Lab at University of Daugavpils tried to determine what intraspecies behaviors pied-billed flycatchers would utilize in light of simulated owl attacks on neighbors in close proximity and at further distances. They found that pied-billed flycatchers did not care about their close proximity neighbors' previous actions and helped them from owl attacks in line with byproduct mutualism of protecting the area from owl invasion. However, at further distances, they would not help pairs that did not assist them in mobbing in their own territory, showing that they can remember previous actions from individuals in their relative area.
25
Cliff Swallow Parasite Load from Communal Living
Dr. Brown and Brown from the University of Tulsa's Department of Biological Sciences set out to determine how the territorial colonial living of cliff swallows were affected by parasite load and potentially other life-history tradeoffs. They determined that this close quarters colonial living led to increased parasite load, which additionally led to offspring that were frailer and smaller, thus less fit due to the parasites stunting their growth. A benefit to this type of living, however, is the ability for high levels and efficiency of communication for food and potential threats.
26
Sharp-skinned Hawk range of prey preference
The Lab of Ecology and Organismal Biology at Indiana State University, led by Dr. Roth II, wanted to determine how the sharp-skinned hawk picked out its prey during wintering months and if the type of movements that the prey were doing mattered to their preference. They found that these hawks preferred intermediate sized to larger sized prey like sparrows, starlings, and mourning doves that were above 20 g, if not they were mostly ignored as the capture reward was not there due to the small prey size. They also found that prey that was isolated and foraging had a much higher chance to be predated on by the sharp-skinned hawk than birds that were not preoccupied or were in large flocks, providing support for foraging prey birds to have higher predation risk, especially when isolated from other birds. These hawks specialized in these intermediate, foraging birds due to their relative ease of capture, with a solid food reward upon capture without the high chance of mobbing or detection from other birds.
27
Mate Guarding and Reproductive Strategy of male Bank Swallows
Michael and Inger Beecher of the Psychology Lab at the University of Washington observed male bank swallows and their mates to see how their behavior changed throughout the whole breeding season. Males engaged in mate guarding by chasing their female mates during their fertilization period, guarding her and the nest from any copulations from other males. However, after their mates' fertility period ends and the egg laying period begins, these males leave and chase other females for the remainder of the breeding season at higher rates, trying to secure as many offspring as possible. This is selected in males as it is costly in time and energy to raise young, especially with only one female and those that are not yours, as opposed to making sure your female that is siring all of your offspring is secured and is only raising your young, and then after trying to pass on your genes further with other females.
28
Preen wiping in Dark-Eyed Juncos
Communication does not have to be vocal! Dr. Whittaker in the Biology Department lab at Indiana University studied communication between dark-eyed juncos with a behavior that was often considered an inconspicuous behavior, bill wiping. Whittaker and her crew measured the amount of bill wiping behaviors done by the males on their preen oil gland in the presence of another male, female, and female with a male call playing. They determined that males were significantly more likely to peck at their preen oil gland and wipe it on their feather using their bill when in mate guarding contexts (female with male sound playing) and in courtship (female present). This olfactory cue that is likely being given off is likely to be part of a multimodal cue of mate choice in females and in communicating and deterring other males.
29
Australian Zebra Finch Artificial Crest "Sexy Sons"
Dr. Burley at the Lab of Ecology and Evolutionary Biology at the University of California, Irvine gave male zebra finches artificial crests ranging from white, red, to green to see if females would have a preference on these artificial ornaments or if they would prefer the control, non-tampered with males. She found that the males with the white crests were significantly preferred by females over the control and the red and green crested males, showing that the females in this population are able to select and show preference toward a trait that hasn't even evolved yet, giving more evidence for "sexy sons" strategies of sexual selection.
30
Songbird large barrier traversal during migration
Dr. Adamík in the department of Zoology at Palacký University and his team committed to attaching light-level geolocators to the following four different species of songbirds to determine their migration strategy over large ecological barriers: collared flycatchers, pied flycatchers, European reed warblers, and aquatic warblers. Two major theories of migration exist for these songbirds, either they migrate over the Sahara and the Mediterranean in one trip of over 50 hours or they take breaks intermittently, only flighting at night and resting in the day. They determined through the light received by the geolocators the birds relative position based on the amount of light that was received by that tracker, and they determined that these four species mainly migrate at night, but when traveling over larger geographic barriers like the Shara or the Mediterranean, they often kept migrating even into daylight to finish their voyage across the barrier. This shows the importance to these species of having safe places to land during their migration, as only a few individuals only flew at night.
If you made it this far, yay! Here's a congratulatory grackle informational end!
Common Grackle
