IMPACT OF TROPHIC CONDITIONS ON BIOLOGICAL PARAMETERS OF GRIFFON VULTURES IN AZERBAIJAN

Introduction

Intensive anthropogenic transformation of landscapes has been causing instability and worsening of trophic conditions for griffon vultures (Gyps fulvus) like many other necrophage birds (Gypaetus barbatus, Neophron percnopterus, Aegypius monachus).Due to direct and indirect effects of anthropogenic factors the number of griffon vulture populations have decreased and their settlements been lost in Western Europe (Spain, Portugal, Italy, Southern France, Australian mountains), Balkan, Crimean peninsula [1, p.141; 4,p.56], Caucasus region [2,p.165; 10, p.14; 12, p.22; 21,p. 83-84], Central Asia [7,p.76; 24,p.205], Altay and Primorye in Russia [13,p.59; 16,p.93;17,p.35] and become extinct in Carpathian mountains as well as in Moldavia [18, p.42; 23,p.303].

Starting from 1960’s international nature protection organizations, states, various charity funds increased financial aid aimed at elimination of negative anthropogenic impacts and the research works on sustainable protection of necrophage birds including griffon vultures intensified. Developments in space surveillance, geo-information systems and computing enabled monitoring and analysis of processes in ecosystems. In this regard, researches targeted at modelling of nest locations, limiting factors, food supply, bioclimatic indicators and bird migrations are being successfully implemented [5,p.186; 6,p.613-614;9,p.25;19,p.127].

The global ‘griffon’ programs executed with the support from European Union, Levantis Fund, Bird Life International, WWF, Royal Society For The Protection of Birds and also Frankfurt Ornithology Society resulted in restoration of both griffon vultures and other necrophage bird populations, and their numbers increased in South-West Europe (Spain, Portugal, Southern France, Alps and others), Balkan (Serbia, Croatia Bulgaria, Greece)  and Crimean peninsula [3,p.52-53;15,p.185; 20,p.122].

Nevertheless, it is worth noting that steady improvement of griffon vulture populations in all their aerials is not observed. This is related to a range of limiting factors that affect those birds and their food supply. Due to civil economical activities there is constant expectation for emergence of new limiting factors in various territories. This claim is further supported by massive vanishing  of necrophage birds (Gyps bengalensis, Gyps indicus, Gyps tenuirostris) in South-East Asia (India Pakistan and Nepal) as a result of wide spread usage of diclofenac drug in treatment of pets.

Currently, more anthropogenic press has further realized loss of griffon vultures in natural systems. This is related to their narrow food adaptation (they feed with animal corpses that are infrequently located) and also to low breeding potential (breeding usually lasts five months, individual bird produces one baby, feeds it for three months, nests not every year). In a limited food supply conditions griffon vultures easily react to changes through worsening breeding, modifications of adaptation characteristics as well as decrease in numbers [8,p.430].

Insufficient information about conditions of griffon vulture populations in poorly researched territories may lead to extinction of this species. Thus, study of griffon vultures, which are included in the Book of Endangered Animals of Azerbaijan with the status of ‘species with insufficient data about its spreading and conditions in Azerbaijan’, in Azerbaijani territory is of high importance since the country is one of the main settlements of these birds not only in Caucasus but also in the entire Eurasian region. Secondly, the number of animals which make the food base of these vultures has decreased due to illegal and unplanned hunting and loss of their living aerials [14,p.50-52]. Furthermore,  during past 20 years, rise in civil economies (i.e. constructions, planting) in settlement areas of griffon vultures, quantitative and qualitative changes in development of cattle-breeding (diminishing pastures, abolishment of collective farms engaged in cattle-breeding, development of cattle-breeding in large indoor complexes, decrease of animals in household economies), growth of vet and sanitation services, utilization of corpses, production of animal produces (i.e. leather, heads, legs, intestines) and other anthropogenic factors caused shrinkage of food supply. Finally, decrease in number of this species during recent years is observed. However, impact study of all those issues on griffon vultures’ biological parameters is still deficient.  Considering all matters discussed above we started studying the factors affecting reproduction and demographic parameters, situation in food supply of griffon vultures, and also determining ways and means for their neutralization in Azerbaijan territory.

Materials  and  Methods

In order to elaborate on this problem we conducted a research in the territory of Turyanchay State National Reserve, one of the main settlements of griffon vultures encompassing an area of 22500 ha, during 2013-2014. Decrease in the number of griffon vultures in this territory during 2004-2012 was the reason for choosing it.

The food base for griffon vultures in the national reserve and the surrounding areas includes corpses of wild artiodactyls animals accidentally fallen from rocks, moved by river floods and killed by predators, trapped predators as well as other pet and wild animals hit by cars on highways or died of diseasesas well as aging. Hence, we held observations near households, roads, river banks, pastures and roads leading to pastures registering the animals. Inputs from local residents assisted us in revealing places with animal corpses and birds gatherings around them.

During June-July of 2013 the animals died withinthe reserve and its neighboring areas were logged and their masses were identified. In parallel, we defined the total masses by multiplying the number of griffon vultures by the number of living masses. By dividing the total masses of dead animals with total mass of griffon vultures we were able to specify food size per individual. It was found that during the period of baby feeding in nests food supply was not sufficient to fulfill the demand of both parents and babies.

In 2014,supplementary food was supplied to griffon vultures with the purpose of optimizing feeding conditions. This process continued from March to November encompassing a period of natural incubation, baby feeding,leaving nests and wintering.
The impact of both food shortage and extra feeding over quantitative dynamics of individuals in populations was studied. For this reason, we registered nests used and not used in colonies, number of pairs engaged and not engaged in breeding, individuals joining emigration and immigration as well as the number of babies in the nests.

Monitoring was conducted en route, on-site, and depending on the landscapes of territories automobile and horses were alsoutilized along with walking. Along the research route and on sites we studied origins and characteristics of negative factors on the birds and their babies in the nesting camps as well as feeding stations.

Devices used during the monitoring included Yukon 10×50 binocular, Kova TSN-601.20x 60 telescopes and also Sony DSC N10 digital still camera.

Results  and   Discussion

It was found that the total mass of corpses died in the national reserve and its surroundings provide each individual with 0,8-1,7 kg of food. A portion of this quantity goes for maintaining a mature individual while 25-50% of it is fed to baby in form of vomitus.

One of the indicators revealing the impact level of ecological factors such as food conditions is the number of pairs engaged in breeding. Considering this we analyzed capacity changes of individuals in populations andbreeding pairs during 2004-2012. It was revealed that the number of individuals in populations in 2004-2012 has changed unsteadily (maximum 33 and minimum 4individuals). For this reason, the number of pairs engaged in breeding gradually felt to 50% during 2004-2009 and 25% during 2010-2012. No baby death found in the nests of brooding.

Certain part of individuals of necrophage birds in populations usually don’t take part in breeding every year. However, the percentage of pairs engaged and not engaged in breeding within populations of necrophage birds is not fully studied. This is related to the fact that minor researches are done on different conditions and species.

Like other necrophage birds griffon vultures enjoy a stable quantity dynamics and they achieve stability in populations according to the opportunities of living conditions. Taking this into account we determined limiting factors affecting unstable changing of quantities in the targeted population as well as the number of pairs engaged in breeding.

Adequate nesting biotopes existing in Azerbaijan and its national reserves is something not considered as limiting factors for griffon vultures. Due to quicker revelation of recreations, shootings and traps in the reserve areas these factors are easily eliminated within the framework of laws. Although transient factors negatively affect the numbers they do not eventually lead to population’s degradation. Furthermore, wide range of adaptation reactions allow birds to escape from fatal outcomes of such factors.

Research results show that the crisis factor unbeatable by griffon vultures is associated with food conditions. During 2004-2012 period of direct and indirect negative impact of anthropogenic factors over food conditions the quantity change happened in population thanks to biotic potential of the species. Because the influence of food shortage is not ‘obvious’ its negative outcomes emerged much later. In such a hypothetical condition the quantity dynamics in griffon vulture populations continued in a fluctuating manner (with intervals), which is not specific to them. Whereas, stable (balanced) quantity dynamics is typical to griffon vultures. Internal hemostasi sand quantity dynamics in its populations are regulated by biological parameters (i.e. structure of population, area of aerial and its structure, species’ attachment to the living habitat, breeding and death levels, mobility). These biological parameters are taken as an indicator reflecting the general condition of the species. Fluctuating change of the vultures’ quantity dynamics that is not typical to its population indicates to changes happening in trophic conditions, which provide their living, and also to the start of degradation process in the species.

During the study of activity of internal regulating mechanism in griffon vultures’ population we found that change in below biological parameters is the cause for a degradation process. That is, since food shortage creates danger for the population the efficiency of mechanisms ensuring stable quantity dynamics has weakened, in return, mechanisms safeguarding decreasing in quantity have arisen. Mutual exchange of information between individuals through sophisticated signal system influencesthe physiological processes in bird organism by means of nerve and hormonal systems, hence, directing the activity of population’s individuals to right direction. As a result, the number of pairs engaged in breeding in the population decreased, however, the emigrating individuals increased. In other words, due to food shortages and in fluctuating conditions the young pairs in the population (they make the reserve group) and some individuals did not participate in breeding by avoiding ‘competition’ with older individuals “in favor of” the population they belong to. The fact that newly developed pairs make the majority of the ones ‘refusing’ to join breeding is also verified in another research.

Successful breeding in populations during food shortage is defined by ‘competition’ among older individuals. Monogamy lowers competition in populations, creates hierarchy and doing so, ensures efficient use of food resources in the territory for the pairs engaged in breeding. That is, the number of breeding pairs in the griffon vultures’ population has decreased in proportion to local food availability. The motive for such breeding strategy is about enabling provision with food the developed babies till their maturing and breeding.

It was revealed that those birds that ‘refrain’ from breeding ‘in favor of’ population and those that emigrate due to food conditions are mainly the young pairs and individuals whose nests are located in periphery and in a diffusion form within the colony, the ones in early nesting stage and with weak social connections. Emigration of the population has put the individuals in danger. First of all, their movement to far areas near human settlements in search for food increases the risk of exposure to danger. Secondly, development and formation of groups in other territories is time consuming. Thirdly, a radio-telemetry study revealed that some of the species flying from Caucasus to Persian Gulf and Arabian Peninsula never return and even die [11,p.18].

These changes happening to the population’s structure have led to weakening of pair development by male and females, social relations and positive “group effect”. All these resulted in shrinkage of demographic indicators in the population of this species whose breeding potential is not so high.  We deemed it necessary to improve food conditions for griffon vultures consideringany deviation from the norm in their population’s structure due to food shortage as an alarming symptom.

Several ‘feeding stations’ were set up in certain places close to the vultures’ population for the purpose of additional feeding. Forfeeding we used wastes from meat shops, meat and poultry processors as well as corpses of animals killed on highways and roads. The food was provided every 5-7 days during March, May, July, September and October matching the quantity of birds near the ‘feeding stations’. For every feeding session each individual received 1,39-1,45 kg of food. If we add this volume to the food available for each bird in the area (0,8-1,7 kg + 1,45-1,39 kg) then the total size per individual made 2,25-3,09 kg.

The ‘feeding stations’ enabled us to restore trophic connections with biotope in the territory under study and they also created conditions for reorganization of individuals, which had left population, in the biotopes. While in 2004-2012 the number of individuals of the population hesitated between 33 and 4, in 2014 this figure increased to 36 individuals. In 2010-2012 the number of breeding pairs was 25%, in 2014 this increased to 61,0%. No baby death was found in the nests of brooding. Nest productivity was one baby per nest.

During the monitoring we noted re-settlement of the immigrant pairs engaged in breeding in their previous nests as well as in unused ones. Settlement of immature individuals in the periphery parts of the colony was observed. Betterment of trophic conditions strengthens trophic connection with biotope in the territory for those unexperienced individuals that left the nests, also increasing the opportunities of pair development for future breeding.

In following years it is planned to carry out additional feeding and monitoring of griffon vultures in the nature. In this regard, we have submitted instruction and monitoring plan to the scientific organization of Turyanchay State Nature Reserveregarding the terms and rules for supplementary feeding.

Findings

Generalization of research materials confirms that the main factor negatively affecting the biological parameters of griffon vultures settled in Turyanchay reserve and its surroundings is degradingfood conditions. Existence of large poultry and cattle breeding enterprises as  wellas meat processors in the territories adjacent to the national  reserveac complishad ditional feeding for griffon vultures.

In today’s conditions of more anthropogenic press on landscapes as well as shrinkage in food base using additional feeding as a biotechnical method in certain zones by including it to protection program can greatly help in a stable development of griffon vultures in Azerbaijan and its worldwide protection.

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