A change in the breeding season of Rüppell's Griffon Vultures Gyps rueppellii in the Serengeti in response to changes in ungulate populations

When introduced to new ecosystems, species' populations often grow immediately postrelease. Some introduced species, however, maintain a low population size for years or decades before sudden, rapid population growth is observed. Because exponential population growth always starts slowly, it can be difficult to distinguish species experiencing the early phases of slow exponential population growth (inherent lags) from those with actively delayed growth rates (prolonged lags). Introduced ungulates provide an excellent system in which to examine lags, because some introduced ungulate populations have demonstrated rapid population growth immediately postintroduction, while others have not. Using studies from the literature, we investigated which exotic ungulate species and populations (n = 36) showed prolonged population growth lags by comparing the doubling time of real ungulate populations to those predicted from exponential growth models for theoretical populations. Having identified the specific populations that displayed prolonged lags, we examined the impacts of several environmental and biological variables likely to influence the length of lag period. We found that seventeen populations (47%) showed significant prolonged population growth lags. We could not, however, determine the specific factors that contributed to the length of these lag phases, suggesting that these ungulate populations' growth is idiosyncratic and difficult to predict. Introduced species that exhibit delayed growth should be closely monitored by managers, who must be proactive in controlling their growth to minimize the impact such populations may have on their environment.

In the Serengeti, predator kills formed from 8 to 45 % of the carcasses that griffon vultures fed upon, the remaining carcasses coming from animals that had died from other causes. But since vultures obtained only very small amounts of food from predator kills, they had to rely for their food supply chiefly on the carcasses that were derived from other causes. In the Serengeti the large proportion of migratory ungulates prevent the mammalian predators from building up to a population size that can be responsible for a large proportion of ungulate mortality. It is estimated that the mammalian predators only take about one quarter of the potential food supply available for carnivores. The remaining ungulates die from various other causes, and so provide food for scavengers which varies in abundance and location with the seasons. This is a food supply which mammalian scavengers cannot easily use but griffon vultures, with their adaptations for gliding flight, are able to exploit it. These vultures therefore exploit a basically different food supply from predators and probably evolved as scavengers of migratory ungulate populations.

The composition and dynamics of the diet of the Black Vulture (Aegypius monachus L., 1766) and Griffon Vulture (Gyps fulvus Hablizl, 1783) were studied in the Talysh region of Azerbaijan in 2014-2016. For this, for 3 years, in June-July, the collection and identification of the remains of food around the nests were carried out. The remains were collected every 10 days from 15 nests of the Black Vulture and 18 nests of the Griffon Vulture. A total of 820 prey items were collected. The vultures’ diet comprised of the carcasses of 24 animal species, including 14 wild mammals, 6 domestic mammals, three reptiles and a fish. 401 prey items were collected at Griffon Vulture nests and 419 items at Black Vulture nests. 188 prey items (46.9%) were gathered in 2014, 117 (29.1%) in 2015 and 96 (24.0%) in 2016 around Griffon Vulture nests. 196 (46.7%) prey items were collected in 2014, 121 (29.0%) in 2015 and 102 (24.3%) in 2016 around Black Vulture nests. The share of the domestic animals was 17.0% (2014), 15.5% (2015) and 10.0% (2016) in the diet of the Black Vulture. The share of the wild animals was 83.0% (2014), 84.5% (2015) and 90,0% (2016), respectively. In the diet of Griffon Vulture these indicators were as follows: the share of the domestic animals was 17.0% (2014), 15.9% (2015) and 14.5% (2016), and the share of the wild animals was 83.0% (2014), 84.1% (2015) and 85.5% (2016). The research confirmed that the diet spectrum of both species in the region has narrowed over 3 years. The diet spectrum reduced by 48.0% in the Black Vulture and by 49.0% in the Griffon Vulture. It was found that the human economic activity has a significant impact on the spectrum and stability of diets of both species in the Talysh region. Therefore, in order to achieve the sustainable development of the populations of both species, it is necessary to organize regular monitoring and supplementary feeding stations. It would be desirable to make an announcement of these territories as natural monuments during the breeding season as well. The local environmental organizations and schools should be involved in the effective protection of such natural monuments.

The purpose of this study was to investigate seasonal changes of spermatogenesis and the cellular localization of P450c17 and P450arom in wild male ground squirrels during the breeding and non-breeding seasons. The testicular weight, testicular size and score count of spermatogenesis from April to September were measured, and histological and immunohistochemical observations of testicular tissues were performed in wild male ground squirrels. In addition, total proteins were extracted from testicular tissue in the breeding and non-breeding seasons and were used for Western blotting analysis for P450c17 and P450arom. There were marked variations in testicular weight, testicular size and score count of spermatogenesis from the breeding season (April) to the non-breeding season (September). Histologically, spermatogonia, primary spermatocytes, secondary spermatocytes and spermatozoa were identified in the breeding season (April). Immunolocalization of P450c17 was detected in Leydig cells and spermatozoa during the breeding season and was only found in Leydig cells during the non-breeding season. The positive signals of P450c17 by Western blotting were both observed in the breeding and non-breeding seasons. Immunolocalization of P450arom was observed in Leydig cells, Sertoli cells and all types of spermatogenic cells including mature-phase spermatozoa in the breeding season, while immunoreactivity for P450arom was not present in the testis of the non-breeding season. With P450arom antibody, a band was also only detected in the breeding season by Western blotting. These results suggest that the seasonal changes in testicular weight and size are correlated with spermatogenesis and immunolocalization of P450c17 and P450arom, and androgen and estrogen may play an important role in the spermatogenesis and testicular recrudescence and regression process.

Bioinspired models for assessing the importance of transhumance and transboundary management in the conservation of European avian scavengers

The random samples item “Vulture Culture” (3 Feb., p. [587][1]) presents the appearance of large numbers of Eurasian griffon vultures in Rajasthan, India, as good news, but this is far from the case. In India, populations of three species of vultures endemic to South Asia (oriental white-backed, long-billed, and slender-billed) have declined to less than 3% of what they were about a decade ago and the decline continues ([1][2]). The Eurasian griffons are mostly immature birds from Central Asia, Tibet, and Mongolia that return there to breed, probably attracted in larger numbers by plentiful supplies of livestock carcasses left uneaten now that the resident species have almost disappeared. There is now substantial published evidence that the cause of the Asian vulture decline is veterinary use of the drug diclofenac, which vultures take in when they feed on the carcass of a cow or water buffalo treated with the drug ([1][2]–[3][3]). Eurasian griffons are as susceptible to kidney failure caused by diclofenac as their Asian relatives ([4][4]), so it is likely that the source populations of this species that winter in India will also be affected. Such an effect will not be detected soon, however, because there is virtually no systematic monitoring of numbers of vultures breeding in these inaccessible areas. Numbers of immature Eurasian griffons wintering in India may continue to grow, but this will probably just indicate a growing drain on their source populations. A ban on the veterinary use of diclofenac, announced by the Indian prime minister in March 2005 ([5][5]), will therefore probably benefit Eurasian griffons as well as the resident species, but only if it can be implemented successfully. The Random Samples item also contained inaccuracies about recently published findings on the safety to vultures of meloxicam, an alternative to diclofenac that could help to save the vultures by speeding the removal of diclofenac from their food supply ([6][6]). The vultures used in the experiments were captive, but not captive-bred, and 72 birds (not 35) were treated, of which 66 were given meloxicam itself, rather than meat from treated cattle. 1. 1.[↵][7]1. R. E. Green 2. et al. , J. Appl. Ecol. (2004)41, 793. 2. 2.1. J. L. Oaks 2. et al. , Nature (2004)427, 630. 3. 3.[↵][8]1. S. Shultz 2. et al. , Proc. R. Soc. London Ser. B (Suppl.) (2004)271, S458. DOI 10.1098/rsbl.2004.0223. 4. 4.[↵][9]1. G. E. Swan 2. et al. , Biol. Lett. (2006)doi:10.1098/rsbl.2005.0425 9. 5. 5.[↵][10]1. P. Bagla , Science (2005)307, 1851. 6. 6.[↵][11]1. G.E. Swan 2. et al. , PloS Biol. (2006)4 (no. 3), e66. [1]: /lookup/doi/10.1126/science.311.5761.587a [2]: #ref-1 [3]: #ref-3 [4]: #ref-4 [5]: #ref-5 [6]: #ref-6 [7]: #xref-ref-1-1 View reference 1. in text [8]: #xref-ref-3-1 View reference 3. in text [9]: #xref-ref-4-1 View reference 4. in text [10]: #xref-ref-5-1 View reference 5. in text [11]: #xref-ref-6-1 View reference 6. in text

The platelet-derived growth factor (PDGF) system is expressed and can exert its biological role in the male reproductive system including the maintenance of morphological structure and function of the epididymis. The aim of this study was to clarify the relationship between the PDGF system and seasonal changes in morphology of the wild ground squirrel epididymis during the breeding and nonbreeding seasons. Hematoxylin-eosin (HE) staining was used to observe the epididymal morphology and histology. Immunohistochemistry and Western blotting were performed to detect the immunoreactivities of PDGF-A and B and PDGFR-α. Significant seasonal changes in epididymal morphology were observed in the breeding and nonbreeding seasons. The proportions of the three compartments (interstitial tissue, epithelium and lumen of the duct) revealed distinct variances. Strong immunostaining of PDGF-A was present in the myoid cell and on the sperm in the breeding season, whereas there was a faint signal in the myoid cell in the nonbreeding season. PDGFR-α was expressed in all cell types of the epithelium throughout the whole seasonal cycle, and immunostaining of PDGFR-α in the breeding season was significantly stronger compared with that of the nonbreeding season. PDGF-B was not detected in the epididymis of wild ground squirrels. These results suggested that seasonal morphological changes in epididymis were correlated with immunoreactivities of PDGF-A and its receptor PDGFR-α and that PDGF-A and PDGFR-α might function as paracrine, autocrine or apocrine factors in wild ground squirrels.

The changes in testicular and pituitary functions in response to human chorionic gonadotropin (hCG) in the breeding and non-breeding season were investigated and compared in the Thoroughbred stallion. Five mature Thoroughbred stallions ranging in ages from 7 to 21 years were injected in May (breeding season) and October (non-breeding season). All animals received an intramuscular injection of 5,000 IU hCG in the experiments. Peripheral blood samples were collected in heparinized tubes from the jugular vein for hormonal assays just before the injection (Day 0) and at a daily interval for five days following the injections (Days 1, 2, 3, 4 and 5). Basal levels of immunoreactive (ir) inhibin, testosterone, estradiol-17β, FSH and LH were higher in the breeding season than in the non-breeding season. There were significant differences in estradiol-17β, FSH and LH between the two seasons. Ir-inhibin exhibited significant increases on Day 2 after the hCG treatment in the non-breeding season, though there was no change in the breeding season. Plasma levels of testosterone showed remarkable increases after the hCG injection in both seasons. The peak levels of plasma testosterone were observed on Days 2 and 3 in the breeding and non-breeding seasons. Plasma estradiol-17β was significantly higher than the basal level on Day 3 in the non-breeding season, whereas there was no change in the breeding season. Plasma levels of FSH declined from Day 1 to Day 3, then recovered to the basal level (Day 0) on Day 4 after hCG treatment in the breeding season, whereas there was no change in the non-breeding season. Circulating LH showed a significant decrease on Day 3 compared to the based level in the breeding season, but no significant change in the non-breeding season after a treatment of hCG. A significant negative correlation was observed between testosterone and FSH in the breeding season. In conclusion, hCG treatment stimulates secretion of testicular hormones and these testicular hormones temporarily suppress secretion of gonadotropins from the pituitary gland. These results also suggested that Leydig cells of thoroughbred stallion testes have LH receptors in the non-breeding season, the same as in the breeding season.

Long-term studies are crucial in ecology, environmental change assessment, resource management and biodiversity conservation. Stercorarius maccormicki (hereinafter – south polar skua) are predators that can threaten populations of bird species of the orders Sphenisciformes and Procellariiformes. At many places in Antarctica, abundance trends for the skua are not known or have not been updated. This study is an attempt to answer the question: how did a south polar skua population react to changes in environmental conditions during 1956–2013? The objectives of the study was (1) to establish the dynamics of the breeding skua population on the Haswell Islands, i.e. Haswell Island and the small islands of the Haswell Archipelago during 1956–2013, and (2) to explain the reasons of the changes in the studied population. A secondary research question was whether there were changes in the spatial distribution of the breeding skua population on the Haswell Archipelago during the study period? The studies have been carried out on the Haswell Archipelago (Davis Sea), mainly in Antarctic Specially Protected Area №127 «Haswell Island and adjacent emperor penguin rookery on fast ice». Ground count was the main method for determining the size of bird colonies. South polar skua bred on 3–8 islands of the Haswell Archipelago. In the study period, the population size of the south polar skua has changed on the Haswell Archipelago. A decrease in the number of individuals (-52%) was observed between 1956–1957 and 1966–1967 breeding seasons. Between 1966–1967 and 1999–2000 breeding seasons, the skua population declined by 30.7% and reached the lowest value of 18 pairs. Population growth (344.4%) was recorded between 1999–2000 and 2009–2010 breeding seasons, with an increase of 33.8% and reaching the maximum value (83 pairs) in 2010–2011 breeding season. By 2012–2013 breeding season, the south polar skua population has declined by 13.2%. On Haswell Island, between 1956–1957 and 2012–2013 breeding seasons, there was a change in skua abundance that was similar to the change in the total breeding population on Haswell Archipelago during the entire period. On the small islands of the Haswell Archipelago, the number of breeding south polar skuas declined (-80%) between 1956–1957 and 1962–1963 breeding seasons. The breeding seasons of 1962–1963, 1966–1967 and 1999–2000 were characterised by the lowest number of individuals. Between 1999–2000 and 2009–2010 breeding seasons, the number of south polar skuas increased by 400%. A decrease in abundance (-41.6%) occurred between 2009–2010 and 2010–2011, followed by the consequent increase (by 36.3%) by 2012–2013 breeding season. During the study period, changes in the abundance of south polar skuas on the Haswell Archipelago were independent of changes in average daily November temperatures between 1956–1957 and 2012–2013 breeding seasons (Mann-Whitney test U = 0, p = 0.0017, n = 7 (asymptotic (2-sided))), when they were laying eggs and heating them. The number of south polar skuas changed independently of changes in the number of individuals of their prey, represented by Aptenodytes forsteri, Pygoscelis adeliae, and Fulmarus glacialoides (respectively U = 49, p = 0.0006, n = 7; U = 16, p = 0.029, n = 4; U = 16, p = 0.029, n = 4 (asymptotic (2-sided))). The high mortality of eggs, chicks and local weather conditions could influence the breeding success of the south polar skua, which could have a delayed effect on their long-term dynamics. Human activities have influenced the skua population, but have not been studied quantitatively. On the Haswell Archipelago, the reasons for historical changes in abundance of the breeding skua population remain largely unclear.

We studied the use of nest-sites by Griffon Vultures (Gyps fulvus) and the breeding success in these sites during 1998–2002 in Gamla Nature Reserve (Israel). Nest-sites in which a breeding attempt succeeded in fledging a young, were more likely to be occupied by nesting vultures in the following breeding season, than nest-sites that experienced a failure. This suggests that Griffon Vultures in Gamla used a Win–Stay/Lose–Shift strategy regarding nest-site fidelity.

We used cohort analysis to evaluate temporal variation in the population density of white-tailed deer (Odocoileus virginianus) at the Canonto Study Area in southeastern Ontario. During continuous study between 1953 and 1986, the population underwent 2 major fluctuations in density, ranging between 1.3 and 7.0 deer/km2. Variation in instantaneous exploitation rates was related linearly to hunting effort, as predicted by the simple random search model used in cohort analysis. Temporal variation in the annual rate of increase of the deer population was largely accounted for by variations in hunting effort and the per capita rate of recruitment. Recruitment rates and growth rates of juveniles showed evidence of delayed, rather than immediate, response to changes in population density. Dynamic interactions between deer and their food supply probably caused similar time lags in both growth and recruitment rates. Such time lags are likely to predispose the population to oscillations, and this tendency was possibly exacerbated by temporal variation in exploitation effort. J. WILDL. MANAGE. 55(3):377-385 Long-term studies indicate that some populations of ungulates exhibit pronounced fluctuations in abundance (Sauer and Boyce 1979, Peterson et al. 1984, Whyte and Joubert 1988). Such long-term fluctuations conceivably stem from a wide range of causes. In exploited populations, temporal variation in harvest rates can lead to pronounced population changes (McCullough 1979, Fryxell et al. 1988). Weather variation over time can also have a strong influence on demographic parameters (Sauer and Boyce 1979, Mech et al. 1987, Owen-Smith 1990). A variety of biotic factors might also contribute to pronounced population fluctuations. Trophic interactions could drive coupled oscillations in both ungulate and vegetation populations (Caughley 1976, McCullough 1979, Sauer and Boyce 1979). This could arise from either delays in recovery of vegetation abundance (Caughley 1976, McCullough 1979) or to induced chemical defenses by attacked plants (Cooper and OwenSmith 1985, Palo 1985, Robbins et al. 1987). Similarly, trophic interactions between ungulates and their predators could contribute to population fluctuations (Gasaway et al. 1983, Peterson et al. 1984). Finally, depressed early growth of ungulates can affect subsequent reproductive success (Albon et al. 1987), which could have a destabilizing influence on ungulate population dynamics. Each of these biotic factors could cause delayed demographic response to changes in population density. We examined the impact of changes in harvest rates and recruitment rates on a fluctuating population of white-tailed deer in southeastern Ontario. We then tested whether there were tim lags in the recruitment response to changes in po ulation density and considered whether d er-plant interactions, deer-predator interactions, or early growth effects could have caused time lags in deer recruitment. Empirical data were gathered by staff of the Ontario Ministry of Natural Resources, under the direction of the Wildlife Research Section, Wildlife Branch. Financial support for the data analysis was provided by the Natural Sciences and Engineering Research Council of Canada. We thank the numerous people who assisted with data collection over the past 3 decades, particularly R. L. Hepburn, who initiated and supervised the Canonto study for many years. We also express our appreciation to the Canonto hunters for their enthusiastic cooperation. D. M. Lavigne, T. D. Nudds, and D. R. Voigt provided useful comments on an earlier draft. This is Wildlife Research Section contribution 90-06 of the Ontario Ministry of Natural Resources.

Oily secretions from the back skin are involved in the marking behavior of male brown bears (Ursus arctos), and apocrine glands in back skin are activated during the breeding season. Here, we investigated seasonal changes in the intracellular organelles of apocrine gland cells in the back skin of male brown bears using transmission electron microscopy (TEM) and osmium-maceration scanning electron microscopy (OM-SEM). The morphological features of mitochondria and intracellular granules, and secretory mechanisms obviously differed between breeding and non-breeding seasons. The TEM findings showed that contents of low-density granules were released into the glandular lumen by frequent exocytosis, and sausage-shaped mitochondria were located in the perinuclear region during the non-breeding season. In contrast, high-density granules appeared in the apical region and in projections during the breeding season, and swollen mitochondria and lysosome-like organelles separating into high-density granules were located in the perinuclear region. The OM-SEM findings revealed swollen mitochondria with only a few partially developed cristae, and small mitochondria with cristae shaped like those in swollen mitochondria in the apical regions during the breeding season. These findings indicated that the small mitochondria corresponded to the high-density granules identified by TEM. These findings suggested that mitochondria in apocrine gland cells swell, degenerate, fracture into small pieces, and are finally released by apocrine secretions during the breeding season. Small mitochondria released in this secretory manner might function as the source of chemical signals in the oily secretions of brown bears during the breeding season.

In recent decades, many ungulate populations have changed dramatically in abundance, resulting in cascading effects across ecosystems. However, studies of such effects are often limited in their spatial and temporal scope. Here, we contrast multi-species composite population trends of deer-sensitive and deer-tolerant woodland birds at a national scale, across Britain. We highlight the divergent fates of these two groups between 1994 and 2011, and show a striking association between the calculated divergence and a composite population trend of woodland deer. Our results demonstrate the link between changes in deer populations and changes in bird communities. In a period when composite population trends for deer increased by 46%, the community population trend across deer-sensitive birds (those dependent on understory vegetation) declined much more than the community trend for deer-tolerant birds. Our findings suggest that ongoing changes in the populations of herbivorous ungulates in many countries worldwide may help explain patterns of community restructuring at other trophic levels. Ungulate impacts on other taxa may require more consideration by conservation practitioners than they currently receive.

Griffon Vultures (Gyps fulvus) are responsible for most cases of usurpation of nests of Bearded Vultures (Gypaetus barbatus). However, little is known about how both species interact during reproduction. We studied territorial behaviour during the breeding season in four Bearded Vulture pairs in the eastern Pyrenees of northeastern Spain. Frequency of agonistic behavior was positively correlated with Griffon Vulture colony size. However, no significantly higher frequency of aggressive interactions was found that suggested actual competition for nest sites between these species. Nonetheless, Bearded Vulture pairs maintained a continuous defence of the area immediately surrounding their nests throughout the breeding season. Our data suggest that the Bearded Vulture's territorial behavior was more closely associated with defence of breeding space than with specific defence of actual nest sites.

The critically endangered Rüppell’s Vulture ( Gyps rueppelli ), originally from sub-Saharan Africa, has recently begun to establish itself in Europe, specifically in the Iberian Peninsula. This study focuses on understanding the spatial ecology of Rüppell’s Vultures during the breeding season, analyzing movement patterns and home-range sizes of three individuals tagged with GPS in southern Spain. The results show significant differences in home-range sizes between adult and immature vultures, with the immature individual exhibiting larger ranges and exploratory behavior, while adults, particularly during breeding, displayed more localized movements. The integration of Rüppell’s Vultures with Griffon Vultures ( Gyps fulvus ), including hybrid breeding attempts, raises conservation concerns regarding potential genetic amalgamation. The study highlights the need for transboundary conservation strategies, as some individuals occasionally enter Portuguese territory during the breeding season. These findings provide crucial insights for the conservation management of this species in Europe, where the vultures’ expanding presence requires coordinated efforts to address threats such as energy infrastructures. Ongoing monitoring is necessary to assess whether these individuals represent a temporary presence or a long-term colonization process.