Crow Populations Research Articles

Increased adult movements and decreased juvenile apparent survival of urban crows during COVID-19 lockdowns

The increasing abundance of animal species thriving in urban environments is a source of conflicts with managers and users of public spaces. Although opportunistic urban species often use resources originating from human food leftovers, the potential impact of a reduction in these resources on their demography is hard to quantify. The COVID-19 epidemic, which led many countries to set up lockdowns, gave us the opportunity to estimate the impact of a drastic reduction in such food resources and human activities on the demography of an urban bird population. Based on 7 years (2015–2021) of capture-mark-recapture of carrion crows (Corvus corone) in the city of Paris, France, we used multi-state models to examine the intra-annual (3-month time steps) apparent survival and movement patterns of crows during and outside COVID-19 lockdowns. We showed that the apparent survival of juvenile carrion crows decreased down during lockdown, while adult movements increased during this period, with more adult crows moving out of the urban district. Lockdown modified the demography of this urban crow population, suggesting that the reduction in food resources was sufficient to affect fitness and reduce carrying capacity.

The impact of population management on urban and rural Hooded Crow populations

Hooded Crow (Corvus cornix), originally native to agricultural areas, has become widespread in urban areas in recent decades. However, this process has negative consequences on urban animals and humans. Due to these problems, the control of urban crow populations is needed. Crows also cause significant damage to wildlife management, and are constantly being controlled in rural areas as well. In this study, we compare rural and urban populations to find out whether hunting activities have a population reduction effect. In the rural population, the reduction is carried out by weapons and traps, while the urban crows are controlled using traps only. In both sample areas, crow nests were surveyed during the nesting period. 29 active nests were monitored in the rural area in 2021, and 39 in 2022. In the urban area, 44 nests were recorded in 2021 and 35 nests in 2022. In 2021, 30 individuals were removed in the rural area, and 84 in 2022. In the urban area, 223 individuals were removed in 2021 and 144 in 2022. Results show that the number of crows removed follows the number of active nests, so that the reduction of a given year is likely to have an effect on the following year's nesting population. Because traps mostly capture juvenile birds, reducing the breeding population in the city can only be achieved in the long-term. Considering this, it is likely that increased attention to population control can effectively maintain crow populations and reduce the problems they cause.

Effects of meteorological conditions on brood care in cooperatively breeding carrion crow and consequences on reproductive success

Meteorological stressors (e.g., temperature and rain shortage) constrain brood provisioning in some bird species, but the consequences on reproductive success have been rarely quantified. Here we show, in a cooperatively breeding population of carrion crow Corvus corone in Spain, that individual feeding rates decreased significantly with rising air temperatures both in breeders and helpers, while lack of rain was associated with a significant reduction in the effort of the male helpers as compared to the other social categories. Group coordination, measured as the degree of alternation of nest visits by carers, was also negatively affected by rising temperature. Furthermore, we found that the body condition of the nestlings worsened when temperatures were high during the rearing period. Interestingly, the analysis of a long-term data set on crow reproduction showed that nestling body condition steadily deteriorated over the last 26-years. Although many factors may concur in causing population changes, our data suggest a possible causal link between global warming, brood caring behaviour and the decline of carrion crow population in the Mediterranean climatic region of Spain.

A Robust Adaptive Hierarchical Learning Crow Search Algorithm for Feature Selection

Feature selection is a multi-objective problem, which can eliminate irrelevant and redundant features and improve the accuracy of classification at the same time. Feature selection is a great challenge to balance the conflict between the two goals of selection accuracy and feature selection ratio. The evolutionary algorithm has been proved to be suitable for feature selection. Recently, a new meta-heuristic algorithm named the crow search algorithm has been applied to the problem of feature selection. This algorithm has the advantages of few parameters and achieved good results. However, due to the lack of diversity in late iterations, the algorithm falls into local optimal problems. To solve this problem, we propose the adaptive hierarchical learning crow search algorithm (AHL-CSA). Firstly, an adaptive hierarchical learning technique was used to adaptive divide the crow population into several layers, with each layer learning from the top layer particles and the topmost layer particles learning from each other. This strategy encourages more exploration by lower individuals and more exploitation by higher individuals, thus improving the diversity of the population. In addition, in order to make full use of the search information of each level in the population and reduce the impact of local optimization on the overall search performance of the algorithm, we introduce an information sharing mechanism to help adjust the search direction of the population and improve the convergence accuracy of the algorithm. Finally, different difference operators are used to update the positions of particles at different levels. The diversity of the population is further improved by using different difference operators. The performance of the method was tested on 18 standard UCI datasets and compared with eight other representative algorithms. The comparison of experimental results shows that the proposed algorithm is superior to other competitive algorithms. Furthermore, the Wilcoxon rank-sum test was used to verify the validity of the results.

Смертность хищных птиц в Северо-Западном Раджастане, Индия (2017–2022 годы)

A major contributing factor in declining populations of vultures is believed to be the widespread use of drugs such as Diclofenac, once commonly-used as a livestock anti-inflammatory drug. Use of Diclofenac is now banned in India. However, during the last 3 years, vulture’s death cases are increasing not only in Rajasthan but also in other parts of India. From 2017–2022, a total of 791 vultures of 3 species i.e. Eurasian Griffon Vulture (Gyps fulvus), Cinereous Black Vulture (Aegypius monachus), and Egyptian Vulture (Neophron percnopterus) and 231 Steppe Eagles (Aquila nipalensis) were found dead at Jorbeer dumping site. Jorbeer has been declared as conserved forest area, but dead livestock dumping site is not part of the protected area. The dramatic vulture decline observed across India leads to the emergence of a range of new ecological threats by influencing the numbers and distribution of other scavenging species. Increased feral dog populations have been reported all over in India, posing many associated disease risks, such as rabies, to humans and wildlife. India already has a very high incidence of rabies, and a severe shortage of quality rabies vaccine in rural areas could further aggravate the problem. Similarly, increased crow populations at carcass dumps in vicinity of settlements pose a risk of infections to poultry, domesticated birds, avian & humans. The situation has improved slightly after the ban on diclofenac (veterinary and human use) in India since 2015, but other drugs used to treat livestock continue to kill migratory raptors and vultures in northern India. The main drugs involved into this are Ketoprofen and Phenylbutazone. The existence of only a small proportion (<0.8%) of ungulate carcasses containing lethal levels of such drugs is sufficient to cause a rapid decline in vulture populations. Strategic planning is needed to protect migratory vultures and eagles from Russia, Kazakhstan and Central Asian countries. While the number of vultures is declining day by day, the death toll in Rajasthan is a major part of the world percentage.

Is the Hitchcock Story Really True? Public Opinion on Hooded Crows in Cities as Input to Management.

Simple SummaryHuman-wildlife conflicts are a novel topic in urban environments. The recent increase in hooded crows in cities across Europe has increased the frequency of such conflicts, and in some places, the control of crow populations has become a necessity and a hotly debated issue. We surveyed the attitude of people towards hooded crows using an online questionnaire developed to assess their knowledge of crows and which control method is acceptable to most people in Hungary. Many respondents had experience with hooded crows and agreed that their high numbers can cause problems. Most people expressed their willingness to learn about the crows and their management yet did not wish to get directly involved in management activities, which they believed should be the responsibility of professionals. In addition, most people supported the use of non-invasive or less harmful control methods and opposed more intrusive or destructive ones. These results clearly express the difficulty in identifying the most suitable and tolerable way to manage urban crow populations and thus address emerging human-wildlife conflicts in urban environments.In recent years, the Hooded crow (Corvus cornix) has become one of the most successful wild bird species in urban environments across Europe. Hooded crows can cause several problems in cities, including trash scattering, noise disturbance, and aggressive behavior toward humans or pets, and they can be potential vectors of pathogens. To find effective solutions, the public has to be involved in the decision-making process in urban planning management, managed by the city administration. In this study, we surveyed the attitude of people in Hungary towards crows and crow management by collecting information using an online questionnaire containing 65 questions published in 14 Facebook groups. We found that many people were familiar with corvid species and had personal experience with them. In most cases, these experiences were not negative, so the crows were not or only rarely perceived to cause problems to people, such as aggressive behavior, damage to cars or stealing something. Most respondents recognized that the presence of large numbers of hooded crows is a problem to be solved and acknowledged that they do not know how to resolve it. The majority of people expressed their interest in raising public awareness of crows but not in their management actions, which they believe should be implemented by experts. Most respondents preferred passive, harmless methods. More direct methods such as egg/chick removal from the nest, control by trapping, poisoned baits or firearms, or oral contraceptives were the least acceptable. These results express the difficulty in identifying a control method for managing hooded crow populations that is both acceptable to most people and effective at the same time. This study demonstrates the importance of involving public opinion in wildlife management and providing more information to citizens to reduce human-crow conflicts.

Identification of top-k influential nodes based on discrete crow search algorithm optimization for influence maximization

Influence maximization refers to selecting a small number of influential nodes in a given network to maximize the influence affected by the subset. In social network analysis and viral marketing, influence maximization is greatly significant. The greedy-based algorithm is time-consuming in estimating the expected influence diffusion of a given node set, which is unsuitable for large-scale network. The traditional heuristics often have the problem of low accuracy. In this study, in order to solve the influence maximization problem more effectively, a meta-heuristic discrete crow search algorithm (DCSA) using the intelligence of crow population is proposed. In DCSA, a new coding mechanism and discrete evolution rules are constructed. The degree-based initialization method and the random walk strategy are adopted to enhance the search ability. Moreover, according to the network topology, influential nodes Candidates are generated to avoid blindness in the process of crow search. Extensive experiments are conducted on six real-world social networks under independent cascade (IC) model, the results show that DCSA outperforms other state-of-the-art algorithms and obtains comparable influence diffusion results to CELF but with lower time complexity.

Association between social factors and gastrointestinal parasite product excretion in a group of non-cooperatively breeding carrion crows

In group-living animals, the social environment is thought to affect the probability of parasite transmission. Here, I investigate relationships between social behaviour and gastrointestinal parasite product excretion in the carrion crow (Corvus corone). Individuals from a population of non-cooperatively breeding carrion crows excreted less samples containing coccidian oocysts when kept in larger groups (8 or 9 individuals) compared to those individuals kept in smaller groups (2 or 3 individuals). Lower-ranking individuals excreted more samples containing parasite oocysts compared to higher-ranking individuals. The strength of affiliative relationships and number of related individuals in the group did not relate to the proportion of droppings containing coccidian oocysts. The present results confirm an association between social environment and parasite excretion patterns in carrion crows, but the patterns described in the present study differ from previously published data derived from a group of cooperatively breeding crows. This illustrates that differences between the social systems of carrion crows might result in different associations between the social environment and parasite product excretion patterns. One major cost of group living is increased susceptibility to parasites. Not all individuals are affected by this in the same way. A better understanding of the relationship between social behaviour and parasite burden can help to better understand evolution of group living. I investigate associations between dominance rank, affiliative relationships, group size, and gastrointestinal parasite product excretion in a group of captive carrion crows. Lower-ranking individuals excreted more samples containing parasite oocysts compared to higher-ranking individuals, confirming an association between social relationships and parasite excretion patterns.

Winter diet and roosting site use of urban roosting Long-eared Owls (Asio otus), and the change in the species’ population size in Southeast Hungary×

Abstract The Long-eared Owl (Asio otus) was chosen as the bird of the year in Hungary by BirdLife Hungary in 2020 to pay more attention to this species. In the present study, we analysed the data collected on the food, changes in the population and the use of the roosting sites of the owls wintering Southeast-Hungary. A total of 4,683 pellets were collected in four winter seasons between 2016 and 2020, of which 5,265 prey animals were identified. We counted the individuals roosting in the winter roosting sites, and from their maximum number we estimated the local population change of the species as well as the success of the breeding. For this, we also used roadkill data from the nearby town, Battonya. The diet of Long-eared Owls in the study area was similar to that observed in other parts of the Carpathian Basin. The smaller differences were mainly due to the different geographical distribution of different prey species. We also identified some species previously having no or very few data, thus we confirmed their stable presence in the area. Different weather factors within the season did not effect owls’ diet. The most varied diet was found in the warmest, least snowy winter. Comparing the feeding data with the data from the 1960s and 1970s, it can be seen that the proportion of preys changed significantly. The proportion of House/Steppe Mice decreased by an order of magnitude, while that of rats increased by the same amount over time. The most likely reasons for this may be changes in agricultural cultivation or local demographic conditions (depopulation). In the 2018/19 season, the proportion of Common Vole in the pellets was much higher than in any other years, suggesting this year’s gradation of the species. The pellets collected in different roosting sites close to each other typically had the same proportions of prey animals. The maximum number of birds observed at the roosting sites did not correlate with the weather of the given season, but was probably related to the effectiveness of the previous breeding season. The population of the species decreased compared to the early 2000’s based on the number of roosting individuals. This may be due to a decline in crow populations. It should be noted, however, that according to both the roadkills in Battonya and the maximum number of the roosting individuals in Kevermes, this drastic decline came to a halt in 2010s.

Wild Bird Survey and Damage Estimation for Some Field Crops at Giza Governorate, Egypt حصر أنواع الطیورالبریة وتقدیر أضرارها لبعض المحاصیل فی محافظة الجیزة - مصر

About 470 bird species known from Egypt. The majority are non-breeding migrants, passing through the country, exploiting the wide range of habitat types unique for their life, including agricultural habitats. A survey of wild bird carried out in three agricultural districts, El-Badrasheen, El-Aayyat and El-Hawamdiah districts, in Giza Governorate, from March 2018 to February 2020, using the point transect method. Twenty-eight species belonging to nine orders and twenty-five families recorded. House sparrow (passer domesticus niloticus) and Hooded Crow (Corvus corone cornix) were the only recorded noxious species, damaging wheat and corn crops. House sparrow damage to wheat start after the first week of the panicles emergence causing 21.4 % and 19 % losses, with the highest loss rate of 5.7 and 6.1% during 1st of April at El-Badrasheen and El-Aayyat districts, respectively. The damage percent were 16.3 and 14.5% to corn by hooded crow in both districts from the 1st week of August up to the 2nd week of September and the highest loss rate were 5.4 and 4.2% during the 4th week of August in the two districts, respectively. It is advisable to apply damage control programs against house sparrow populations at the beginning of February in wheat fields, and against hooded crow populations at the beginning of June in corn fields in these areas.

Cryptic and extensive hybridization between ancient lineages of American crows.

Most species and therefore most hybrid zones have historically been defined using phenotypic characters. However, both speciation and hybridization can occur with negligible morphological differentiation. Recently developed genomic tools provide the means to better understand cryptic speciation and hybridization. The Northwestern Crow (Corvus caurinus) and American Crow (Corvus brachyrhynchos) are continuously distributed sister taxa that lack reliable traditional characters for identification. In this first population genomic study of Northwestern and American crows, we use genomic SNPs (nuDNA) and mtDNA to investigate the degree of genetic differentiation between these crows and the extent to which they may hybridize. Our results indicate that American and Northwestern crows have distinct evolutionary histories, supported by two nuDNA ancestry clusters and two 1.1%-divergent mtDNA clades dating to the late Pleistocene, when glacial advances may have isolated crow populations in separate refugia. We document extensive hybridization, with geographic overlap of mtDNA clades and admixture of nuDNA across >900km of western Washington and western British Columbia. This broad hybrid zone consists of late-generation hybrids and backcrosses, but not recent (e.g., F1) hybrids. Nuclear DNA and mtDNA clines had concordant widths and were both centred in southwestern British Columbia, farther north than previously postulated. Overall, our results suggest a history of reticulate evolution in American and Northwestern crows, perhaps due to recurring neutral expansion(s) from Pleistocene glacial refugia followed by lineage fusion(s). However, we do not rule out a contributing role for more recent potential drivers of hybridization, such as expansion into human-modified habitats.

Managing Urban Crow Populations in Japan

Managing Urban Crow Populations in Japan

The crow in the room: New Caledonian crows offer insight into the necessary and sufficient conditions for cumulative cultural evolution.

New Caledonian (NC) crow populations have developed complex tools that show suggestive evidence of cumulative change. These tool designs, therefore, appear to be the product of cumulative technological culture (CTC). We suggest that tool-using NC crows offer highly useful data for current debates over the necessary and sufficient conditions for the emergence of CTC.

An Improved Crow Search Algorithm Based on Spiral Search Mechanism for Solving Numerical and Engineering Optimization Problems

The crow search algorithm (CSA) is a new intelligent optimization algorithm based on the behavior of the crow population, which has been proven to perform well. However, its simple search mechanism also leads to the algorithm's slow convergence speed and its ease of falling into local optimization when solving complex optimization problems. In order to overcome these problems, this paper proposes an improved CSA (ISCSA) based on a spiral search mechanism. By introducing a weight coefficient, an optimal guidance position and a spiral search mechanism, the position equation was updated to accelerate the convergence of the algorithm and make the exploration and exploitation of CSA more balanced. Meanwhile, adding Gaussian variation and random perturbation strategy made it difficult for the algorithm to fall into local optimization. The advantages of the proposed ISCSA were evaluated using 23 benchmark functions and four classical engineering design problems. The experimental and statistical results of 23 test functions showed that the proposed ISCSA could escape from the local optima with higher accuracy and faster convergence than both the CSA and other meta-heuristic optimization algorithms. The calculation results of the four engineering optimization problems showed that compared with other algorithms, ISCSA can solve the practical optimization problem well and has been proved to have strong competitiveness and good performance.

Detection of West Nile virus by real-time PCR in crows in northern provinces of Iran.

West Nile virus (WNV) is a positive-sense, single-stranded RNA virion, that belongs to the Flaviviridae family. This virus is preserved in a bird-mosquito cycle that is capable of inducing diseases as a dead-end or endpoint host in humans as well as horses. In 2016, a suspicious case of crow population death was reported by the Department of Environment, Ministry of Health, Iran. Considering the mass migration of birds together with the WNV-related symptoms, including uncoordinated walking, ataxia, inability to fly, lack of awareness, and abnormal body posture, it was necessary to further investigate the possible causes of this incident. The objective of this study was molecular detection of WNV in crows utilizing the real-time PCR method in the northern provinces of Iran. A total of 12 crows (8 dead, 4 alive) with a possible WNV infection, were collected from the northern provinces of Iran (Golestan, Mazandaran, and Guilan). A tissue sample of the liver, kidney, or lung was collected from all the crows, and RNA was isolated using an RNA extraction kit. A one-step real-time PCR method using a TaqMan probe was used for virus detection. All the infected crows were positive for WNV. The 132-bp real-time PCR amplicon of the genome was detected in all the samples. Comparative phylogenetic analysis revealed that WNV isolated from Iran clustered with strains from the USA, Hungary, and Culex pipiens. The WNV genome sequence was detected in all the infected crows. The results confirmed the connection of this isolation with clade1a strains. Hence, determining the epidemiologic and prevalence characteristics of the WNV for transmission control is of critical importance in Iran.

Why do zoos attract crows? A comparative study from Europe and Asia.

Crows have successfully colonized many cities, and urban zoos have been important in this process. To evaluate why zoos attract crows, we quantified crow numbers and behavior in three zoos in Europe (Debrecen, Edinburgh, Vienna) and one in Asia (Sapporo). Data were collected in 445 surveys over 297 days in summer 2014 and winter 2014–2015. We found that crow numbers were highest in Vienna, intermediate in Debrecen and Edinburgh and lowest in Sapporo, increased significantly from summer to winter (Debrecen, Edinburgh, Vienna), and from mornings to afternoons (Debrecen, Sapporo, Vienna), and were higher in sunny weather than in cloudy weather with precipitation and when visitor numbers were low (Debrecen, Vienna). The crows' use of natural food was highest in Vienna, intermediate in Edinburgh and Sapporo, and low in Debrecen. The use of anthropogenic food was high in Debrecen and Sapporo, where the availability of open grassy areas typically used by crows for natural foraging was low. In Sapporo, food availability was more limited than in other zoos, resulting in strong territoriality and few crows in summer, which decreased further in winter. Our study indicates that crows are primarily attracted to zoos by food availability and secondarily by breeding opportunities and that the relative importance of natural versus anthropogenic food sources may vary with zoo habitat structure. Our study draws attention to a previously overlooked role of zoos in urban biodiversity conservation. It may also provide useful information for the management of crow populations, if necessary, and for the planning of urban areas.

Affiliative social relationships and coccidian oocyst excretion in a cooperatively breeding bird species

In group-living animals, behavioural interactions with conspecifics strongly modulate an individual's physiological stress response. Stable social relationships may reduce an individual's stress response, which in turn can affect the immune system and health. Ultimately, positive health effects of stable social bonds may contribute to maintaining group living. We investigated whether, in cooperatively breeding carrion crows, Corvus corone, the quality of social relationships correlates with the excretion of coccidian oocysts and nematode eggs. We repeatably collected behavioural data on dyadic social interactions and individual droppings to quantify parasite eggs and oocysts from 36 individuals in a captive population of carrion crows in northern Spain. Individuals with strong social bonds, living with more relatives and in larger groups, excreted a significantly smaller proportion of droppings containing coccidian oocysts. The probability of excreting droppings containing nematode eggs was not affected by social factors. The relationship between social interactions and coccidian oocyst excretion is consistent with the idea that high-quality social relationships can positively affect an individual's health, setting the stage for the evolution of stable social living.

Age-related differences in diet and foraging behavior of the critically endangered Mariana Crow (Corvus kubaryi), with notes on the predation of Coenobita hermit crabs

Knowledge of foraging behavior across life stages of endangered species is important for identifying potential drivers of age-dependent mortality. Juvenile mortality is a primary threat to the persistence of the single remaining Mariana Crow (Corvus kubaryi) population, which is found on Rota, Commonwealth of the Northern Mariana Islands. Therefore, variation in foraging behavior among fledglings, sub-adults and adults may highlight different needs or susceptibilities that could inform age-specific management strategies. During observations of 36 Mariana Crows, we found that of all food captures, 14% were plant-based, 56% were insects or their larvae and eggs and 30% were non-insect animal prey. Two food categories, fruits/seeds/plants and ants/termites/larvae, which were procured and processed with simple behaviors, were taken more frequently by fledglings. Crabs, which were processed using complex behaviors, were captured more frequently by adults. Adults acquired more food items from the ground than did fledglings and sub-adult birds, a result that was driven by the former’s high level of crab predation. We did not detect differences in foraging behavior between wet and dry seasons, suggesting that Mariana Crows maintain a similar diet year-round. Overall, our results highlight age-related differences in foraging behavior; however, future studies should identify whether these differences drive age-dependent variation in survivorship. Finally, we suggest that complex trophic interactions between non-native snails and Coenobita hermit crabs may have modified Mariana Crow foraging behavior, increasing their vulnerability to feral cat predation.

Waste Disposal Sites as All-You-Can Eat Buffets for Carrion Crows (Corvus corone).

Simple SummarySeveral bird species like common ravens, carrion crows, hooded crows, and rooks are held responsible for damage to agricultural land and crops. Especially in urbanized areas, they are increasing in abundance and are considered nuisance animals. We estimated the population size of carrion crows over the course of one year in relation to waste and non-waste sites in the federal state Vorarlberg, Austria. The current study showed that several human-related food resources influence the abundance of crows. More crows were observed in survey areas of biogas production and green-waste sites compared to reference sites 3 km distant from waste sites. Continuous hunting activities over the past two decades have not reduced population size. We suggest that the sustainable long-term stabilization and reduction of generalist corvid species populations can only be achieved if anthropogenic food resources are limited.In cities and densely populated areas, several corvid species are considered nuisance animals. In Austria, particularly carrion (Corvus corone) and hooded crows (C. cornix) are regarded as pests by the general public that frequently cause damage to crops, feed on human waste, and thus spread trash. We conducted a detailed one-year field survey to estimate the abundance of carrion crows in relation to potential anthropogenic food sources and reference sites in the Austrian Rhine valley. Our results demonstrated that the number and proximity of waste management facilities, animal feeding areas, and agricultural areas, and the productive capacity of agricultural areas, predominantly influenced habitat choice and abundance of carrion crows. In the current study, the probability of observing more than two carrion crows at a survey site decreased with increasing human population density. Moreover, the abundance of crows increased despite a continuous increase in crow hunting kills registered during the past 25 years. Our study suggests a regionally comprehensive waste management plan could serve as a promising strategy to manage nuisance birds. A reduction in anthropogenic food supply through improved waste management practices is required for long-term, sustainable management to limit the abundance of crow populations in and close to urban environments.

The aryl hydrocarbon receptor 2 potentially mediates cytochrome P450 1A induction in the jungle crow (Corvus macrorhynchos)

To understand the role of aryl hydrocarbon receptor (AHR) isoforms in avian species, we investigated the functional characteristics of two AHR isoforms (designated as jcAHR1 and jcAHR2) of the jungle crow (Corvus macrorhynchos). Two amino acid residues corresponding to Ile324 and Ser380 (high sensitive type) in chicken AHR1 that are known to determine dioxin sensitivity were Ile325 and Ala381 (moderate sensitive type) in jcAHR1 and Val306 and Ala362 (low sensitive type) in jcAHR2. The quantitative comparison of the two jcAHR mRNA expression levels in a Tokyo jungle crow population showed that jcAHR2 accounted for 92.4% in the liver, while jcAHR1 accounted for only 7.6%. Both in vitro-expressed jcAHR1 and jcAHR2 proteins exhibited a specific binding to [3H]-labeled 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). Transactivation potencies for jcAHR1 and jcAHR2 in in vitro reporter gene assays were measured in jcAHR-expressed cells exposed to 16 dioxins and related compounds (DRCs). Both jcAHR1 and jcAHR2 were activated in a congener- and an isoform-specific manner. EC50 value of TCDD for jcAHR2 (0.61 nM) was six-fold higher than that for jcAHR1 (0.098 nM), but jcAHR2 had higher transactivation efficacy than jcAHR1 in terms of the magnitude of response. The high transactivation efficacy of jcAHR2 in DRCs is in contrast to that of AHR2s in other avian species with low transactivation efficacy. Molecular docking simulations of TCDD with in silico jcAHR1 and jcAHR2 homology models showed that the two sensitivity-decisive amino acids indirectly controlled TCDD-binding modes through their surrounding amino acids. Deletion assays of jcAHR2 revealed that 736–805 amino acid residues in the C-terminal region were critical for its transactivation. We suggest that jcAHR2 plays a critical role in regulating the AHR signaling pathway, at least in its highly expressed organs.