There are four fundamental decisions that most animals make when it comes to mechanisms of adaptation: where to live, how to gather food, how to avoid predators, and what tactics to use to reproduce (Alcock, 1993). Habitat preferences in animals require satisfying their needs (ignoring or actively avoiding others, nutritional needs to perform growth, development and reproduction) at the same time experiencing higher fitness than those unable to settle in the favored habitat. There were also several hypothesis presented which correlates habitat preference and fitness.
The seasonal dispersion of some animals like ducks is a costly business in terms of energetic expenses and risk to exposure to predators. On the other hand, considering dispersal cost, animals that do not respond to dispersion pay the price of deterioration due to the inability to adapt to the prevailing ecological conditions. Considering the inbreeding avoidance hypothesis (Ralls et. al, 1979), on ducks in particular, Mallard ducks may have migrated then for the purpose of expanding their genetic pool by interbreeding with Anas rubipes a close relative of the Anas playrynhos.
The costly dispersal of Mallards may have been to avoid inbreeding depression primary of which is to circumvent the expression of damaging recessive alleles resulting from the mating of two closely related mates of the same species. This further correlates with the mate competition hypothesis (Moore and Ali, 1984), which states that males tend to fight against one another for mates therefore looser find it more energy efficient to seek closely related species to which they may successfully mate. When mating season is over, male disperses to avoid their daughters when these female become sexually mature.
Animals engage into energetically exhaustive activity trying to complete the course of their journey to attain its fundamental goals. As the animal arrives to its destination, the issue of territoriality always comes to mind whenever a new species is introduced into a new environment and every time the visitor interacts with the native. While other animals ignore or tolerate the presence of a new species in its territory, others are extraordinarily aggressive in defending their territory from intruders.
Territoriality among animals contributes to reproductive successes or failure to the contrary which further leads to interspecific competition. If suitable breeding sites really are short of supply, then one should be able to find non-territorial, non-breeding, individuals in populations of territorial animals. If this is so, the niche similarity of the visitors to the native may introduce interspecific competition with the available supplies. Territoriality may also influence the reproductive success of these visitors as it was found by Dhondt and Schillemans (1983).
Territorial animals may invade the nesting sites of migratory birds which may lead to decreased viability and clutch. The ability of birds to fly and survive various environmental conditions has led to their development over time. Seasonal migration of mallard ducks (Anas platyrynchos) has been one of the intriguing aspects of its behavior. This behavior has been influenced mainly by several factors such as foraging (Heitmeyer, 2006), competition (Mc Auley, et al.
, 2004), reproductive behaviors (Hill, 1984) which also includes the preservation of nesting sites, and interbreeding (Brodsky, 1989) and seasonal weather conditions (Ridgill, et al. , 1990 in D. Hill, 1992, Whyte & Bolen, 1984, Poiani & Johnson, 1991). Statement of the Problem From previous articles, it has been reported that Mallard ducks are reoccupying old territories throughout the United States and Canada (Talent, et. al. , 1983). From this observation, it can be inferred that various ecological changes in both habitat and inhabitants may take place.
Since mallard ducks in this regard are annual visitors in these habitats, the temporary habitation of previous and new territories may significantly affect native animal species. With the combined hypothesis that Mallard ducks migrate from previously occupied territories due to overlapping conditions which may occupy new territories due to insufficiency of the previous, the study will assess the behavioral patterns of Mallard ducks towards returning to previous foraging territories and establishing new foraging regions (migratory routes) outside of their original habitats, specifically the study will address four major areas of concern.
1. What behavior of the Anas playrynchos determines the suitability of a habitat to be considered sufficient which helps it decide to inhabit previous foraging territories and new regions outside of their original habitats? 2. What behavioral mechanism will the Anas platyrynchos exhibit upon visiting a previous foraging territory and new regions outside of their original habitats if a highly territorial organisms was encountered upon landing? 3.
What general behavioral model applies during the interaction of two closely related species (Anas rubipes and Anas platyrynchos) occupying the same niche in terms of: a. Reproductive tactics b. Foraging preferences c. Territoriality 4. What chances that the introduction of less territorial animal may cause significant adaptive stress (competitive stress) to a more territorial species? Hypotheses It is hypothesized that there is no significant differences in the previously reported behavioral mechanisms in Anas platyrynchos that helps it determine to decide on its habitat preferences.
Alternatively, Anas platyrynchos establishes new migratory routes due to impending factors such as avoidance of predators, seasonal weather conditions, reproductive tactics and foraging preferences. Else, Anas platyrynchos establishes new migratory route or return to previous foraging areas due to certain conditions such as habitat destruction, scarcity of supplies needed to reproduce, and extreme territoriality between natives and migrants.
Experimental Design In order to test these hypotheses, the study will be divided into two phases: the in vivo phase and in vitro phase. At the in vitro phase, groups of experimental populations of Mallard ducks will be placed in a study area which will allow observation of significant behavioral patterns relevant to foraging, reproductive tactics/quality such as mate preference, clutch size, egg size and viability, and interspecific competition.
Two species of closely related species of ducks the Anas rubipes (native, will be allowed to acclimatize until such time that they one or two reproductive cycles have been achieved) and Anas platyrynchos (introduced species, will be introduced only after the native have been acclimatized well) will be situated in the same habitat which will be observed for close interaction. Behavioral patterns on mate preferences and competitive exclusion will be observed by on-site observation using a hidden observation platform.
Foraging preferences will be looked upon by collection and analysis of droppings from both species. Geographical invasion of feeding territories will be looked upon by assigning quadrat areas which will be initially determined by the territorial preferences of both species of ducks. Territoriality will be measured by the number of times the more aggressive native will disturb the nesting sites of the migrants and the instance that the migrant will be driven away from a specific foraging site. Specific effects of such behavior will be measured by performing initial and final biometry of the two species of ducks.
Decrease in biometric qualities from both adult and eggs would mean the inability to adapt into such competitive behavior. Possible effects of migrant foraging on native non-avian species will also be observed by recording the feeding activity of non-avian species living along the vicinity which might directly contribute to the promotion or disruption of the food chain brought about by the introduction of a new consumer. To observe the habitat preference of ducks with is natural behavior in its intact natural behavior, the in vivo phase will be done.
Radio satellite transceivers will be wing banded on representative Anas platyrynchos through catch and tag method (including the alpha male) that are about to engage into seasonal journey to trace their possible destinations and stop-over. The result will be compared to previous annual migration data (20 years in succession or more depending on the available information) to establish a pattern supporting the behavioral mechanism that the ducks employ in selecting a habitat which sooth their preference.
On site visitation of previously reported migration destinations will be surveyed to confirm habitation of previously occupied regions. Ecological evaluation and mapping of visited areas (stop-over and final destination) will be done and compared with other visited areas for specific pattern. Thorough monitoring of migration paths via remote sensing will be followed to confirm if ever there is a change in the migratory route. Conclusions will be based on the assessment of significant differences between the previously reported data and the novel information. Summary
All in all, birds may move to various locations for survival. If the prevailing conditions decrease fitness, migratory ducks may move to different locations to continue to find food, reproduce and avoid predation. When the conditions increase fitness, these ducks will then return to their natal site where they will breed and raise their young. It may be that physical conditions and forces that govern the earth’s magnetic poles, hormonal changes, changing weather patterns or other various factors contribute to the birds’ urge to migrate to their seasonal habitats.
For the purpose of this paper, the most important factor to be considered are the consequences to native animals belonging in the same niche brought about by abrupt or gradual changes in migratory routes and the resulting occupation of new or old territories. In the evolutionary perspective, animals are able to adapt into their environment mainly by employing specific behavioral mechanisms that would enable them to perfectly cope. At the event that an animal fails to establish equilibrium with its environment, serious complications arise.
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