Impacts of Deforestation on Forest Raptors and Conservation

Strategies

Regina C. Y. Liu

Faculty of Science, University of Queensland, Brisbane,4072, Australia

Keywords: Forest Raptors, Deforestation Impact, Conservation Strategies, Eucalypt Habitats.

Abstract: Forests are critical ecosystems that support diverse biodiversity and provide essential ecosystem services.

However, rampant deforestation primarily driven by human activities threatens these ecosystems and the

species that depend on them. This paper specifically addresses the impact of deforestation on forest raptors, a

group highly vulnerable due to their dependence on forest environments for nesting and prey. By synthesizing

findings from twelve studies across neotropical, temperate, and boreal forests, this review highlights the dire

consequences of deforestation, including the loss of prey and nesting sites, which critically endanger these

avian predators. Additionally, the paper evaluates two potential conservation strategies: the use of eucalypt

forests as alternative habitats and the implementation of artificial nests, discussing their effectiveness and

limitations in preserving raptor populations and biodiversity. Furthermore, the study considers the adaptive

behaviors of raptors in response to changing forest landscapes, suggesting potential resilience mechanisms

that could be supported through targeted conservation efforts. It also addresses the policy implications of these

findings, advocating for stronger legislative measures to protect critical habitats. Finally, the paper calls for

more collaborative research initiatives that integrate ecological, socio-economic, and cultural perspectives to

enhance conservation strategies for forest raptors and other wildlife impacted by deforestation.

1 INTRODUCTION

Forests are essential for providing ecosystem services

like stabilizing climate and supporting 80% of

biodiversity on land. Forests are shrinking at an

alarming rate due to anthropogenic activities. Primary

causes include deforestation and land conversion for

agricultural production, livestock grazing, and timber

exploitation (Carrete et al., 2009; McClure et al.,

2018 & Healey, 2020). Forest degradation by

deforestation threatens the balance of ecosystems and

the survival of many animals that rely on it, and

reduced biodiversity is the result of habitat

degradation and fragmentation.

Raptors, such as hawks, eagles, and owls, are

birds of prey that play a vital role in shaping the forest

ecosystem by being flagship and umbrella species on

the highest trophic level (Carrete et al., 2009). Their

presence is frequently represented as an

environmental indicator of healthy biodiversity and

habitat quality, controlling the prey population and

having cascade effects on ecosystems. Raptors are

strongly influenced by features of the canopy and

sub-canopy (Piana and Marsden, 2014). Analysis

indicates that raptors are more in peril than other birds

(McClure et al., 2018 & Labra et al., 2013), and

ecosystem conversion and ecosystem degradation are

the greatest stressors that raptors face (McClure et al.,

2018).

Understanding their behaviours and habitat

preferences allows efficient conservation. However,

these elusive birds are difficult to track and study,

and most of their habitat selection preferences,

population dynamics, and conservational status

remain unclear. By analyzing previous studies of

forest raptors in neotropical, temperate, or boreal

forests, this paper aims to integrate the known

information and interpret the effects of land clearing

on forest raptors. This paper also evaluated and

commented on two possible conservational methods,

with the first study investigating eucalypt trees for

being forest raptors' nest preferences and the last

study of the use of artificial nests.

Liu, R. C. Y.

Impacts of Deforestation on Forest Raptors and Conservation Strategies.

DOI: 10.5220/0013844200004914

Paper published under CC license (CC BY-NC-ND 4.0)

In Proceedings of the 2nd International Conference on Renewable Energy and Ecosystem (ICREE 2024), pages 35-40

ISBN: 978-989-758-776-4

2 SCALE AND CAUSES OF

DEFORESTATION

Deforestation are the removal of forest biomass and

the conversion to other land use. The fertile

soil allow agriculture and civilisation to prosper and

support populations around the world. However,

colonial deforestation throughout history and

the over-exploitation of forest in the contemporary

world had concerning effects on the environment

and quality of life of people (Barraclough and

Ghimire, 1995).

Large-scale land clearing is occurring in

deforestation fronts globally, with one hectare of

forest degraded every second; over half of the tropical

forests have been lost since 1960 (Healey, 2020). The

resources commercially extracted from tropical

forests are often supplied to developed countries,

with communities being exploited for labour

(Barraclough and Ghimire, 1995). Furthermore,

colonial deforestation had negatively impacted the

socio-economic aspects of 70 million indigenous

people whose livelihood relied on the forest (Healey,

2020). With the change in regional climates comes an

increased risk of flooding and water insecurity

(Barraclough and Ghimire, 1995), and many who are

dependent on forests lose resources when

land is degraded.

The depletion of forests is accelerating. With

reduced ecosystem functions and services provided

by forests, there are aggregated impacts of climate

change and ecosystem collapses. The main causes of

deforestation in recent decades are expanding

agriculture (Piana and Marsden, 2014 & Barraclough

and Ghimire, 1995) and the unsustainable logging

and commercial exploitation of wood as fuel also

accounts for most of the forest degradation. Other

pressures include having infrastructures,

transforming land to urban settlement, building

hydroelectric project and mining etc (Healey, 2020 &

Barraclough and Ghimire, 1995).

3 IMPACTS OF

DEFORESTATION ON

RAPTORS

3.1 Impacts on Species Susceptibility

Raptors, sitting on the highest level, are apex

predators that prey on other animals; they have

evolved adaptations to thrive in almost every type of

habitat (McClure et al., 2018). In terms of forest

biomes, forest raptors are top predators that have top-

down effects on ecosystems; they are considered the

keystone species that hold the structure of biological

communities, having the service of regulating and

maintaining the ecosystems.

With threats like reduced habitats and

being subject to hunting, raptors are declining

globally, with 18% classified as threatened with

extinction (McClure et al., 2018). Some species are

more vulnerable to habitat alternation than others

based on their foraging habitat, nesting, and

reproduction preferences (Carrete et al., 2009).

Identifying species that are more susceptible to

deforestation is essential for evaluating conservation

priorities.

Among avians, raptors are more prone to human

activities due to their ecological traits (Labra et al.,

2013); non-migratory forest raptors, especially

species found in the tropics, are more likely to be

threatened by human activities (McClure et al.,

2018). Of 557 species of raptors, 258 species

specifically require forest as habitat, and over 80%

of species have regular or frequent use of forests

(McClure et al., 2018). Neotropical raptors heavily

depend on old mature forests in Central America, and

different species respond differently to altered

habitats: while for almost all other neotropical raptor

species, deforestation had become the most

significant threat for their declining numbers,

Plumbeous Kite, Bicolored Hawks, Roadside Hawks,

Laughing Falcons, and Bat Falcons are more resilient

to deforestations (Whitacre and Peregrine, 2012).

Study results in Peru show that moderately controlled

cattle grazing could benefit and increase the

dominance of generalist species like Harris Hawk,

Black, and Turkey Vultures (Piana and Marsden,

2014). However, raptors like the Great Black Hawk

and the Gray-backed Hawk are more susceptible to

the effect of cattle grazing and struggle to maintain

populations.

A regional raptor survey was done by Carrete et

al. in selected biomes, with forest habitats including

the Paraná forest, which has a fragmented semi-

deciduous rainforest, and the Patagonian mountain

forest. Higher raptor species richness and

diversity were recorded in natural habitats with low

degrees of deforestation, and larger patches of forest

sustain higher levels of raptor assemblages than

smaller fragmented patches (Carrete et al., 2009). The

main leading causes of raptor decline are habitat loss

and fragmentation. A raptor survey by De Labra

investigates the composition and abundance of raptor

species in Mexico forests and reported lower

ICREE 2024 - International Conference on Renewable Energy and Ecosystem

encounter frequencies for most species, with three

species only being found in heavily forested regions

(Labra et al., 2013), contrasting to the frequencies of

encounter reports in well-conserved areas.

3.2 Impacts on Diet and Prey

Abundance

Smaller territories range among raptor individuals

and are associated with abundant food availability;

interspecific competition decreases when food

resources are sufficient and the habitat can sustain a

larger raptor community (Segura and Acevedo,

2023). The complex spatial structure of mature

forests allows raptors like the Harpy Eagles to forage

in high prey-density areas (Vargas et al., 2020). The

breeding pair's habitat selection is strongly associated

with food availability (Segura and Acevedo, 2023).

It is safe to interpret that deforestation impacted

raptors' survival fitness by limiting their energy

supply and intake. Deforestation affects organisms at

all trophic levels, decreasing the prey abundance of

some species. By limiting available tree hallows and

canopy covers, canopy dwelling, and arboreal prey

decreases. Raptors with specialized diets or unique

sub-canopy hunting styles, like Crested Eagles,

Hook-billed kites, and Orange-breasted falcons, are

more adversely affected by prey abundance and have

a higher intrinsic vulnerability to the impacts of

deforestation. Crested Eagles hunt nocturnal, arboreal

mammals in sub-canopy, and their prey declines with

deforestation, Hook-billed kites are arboreal snail

specialist, feeding dominantly on tree snails, Orange-

breasted falcons prey comprising aerial species of

birds dwelling on treetops and sub-canopy, and land

degradation caused altered hunting grounds, and their

hunting success rate decreased (Whitacre and

Peregrine, 2012).

The canopy and sub-canopy provide perching

sites for forest raptors (Piana and Marsden, 2014 &

Whitacre and Peregrine, 2012); removing raptors'

natural prey habitats, causing a decrease in prey

population might also force raptors to hunt and feed

on domestic animals, like calves and poultry (Labra

et al., 2013). This created conflicts between residents

in the local area, and raptors were shot and killed by

local farmers (Labra et al., 2013 & Whitacre and

Peregrine, 2012). Furthermore, human-caused

mortality directly accounted for the decline of the

raptor population by hunting or poaching, while

raptor prey animals being hunted by humans also

reduced the raptor's prey availability.

3.3 Impacts on Nesting Preferences and

Habitats

Raptors are territorial predators that occupy defended

territories to forage and reproduce. Studies about

forest raptors' nesting selections corroborate the

importance of the quality and quantity of nesting sites

to the raptors' community and populations. The now

vulnerable Harpy Eagles require high forest cover as

breeding sites and habitat alteration have limited their

breeding success (Vargas et al., 2020). Honey

Buzzards and Lesser Spotted Eagles also have a

strong preference for nesting in natural forests 20],

with natural stand composition, location, tree sizes,

and old-growth structure being driving

variables. Species like Booted Eagles have a strong

preference for tall trees with dense canopy cover that

provides shelter for nests from thermal extremes;

hence, the dense breeding population of Booted

Eagles was found only in mature forests (Segura and

Acevedo, 2023).

Breeding nests are resources that are usually

reused by many species, and the destruction of

existing nests reduces the survival fitness of

individuals (Segura and Acevedo, 2023 & Franco et

al., 2018). Deforestation in forests with mature trees

removes suitable nesting platforms and reusable

breeding nests for forest raptors. Unprotected areas

with less nesting availability might result in

the raptor's declining abundance, species richness,

and reproductive success (Segura and Acevedo,

2023).

Since forest raptors have a heavy reliance on

mature trees as breeding and nesting sites (Whitacre

and Peregrine, 2012 & Franco et al., 2018), with the

ongoing rate of deforestation, evaluating the impacts

of land clearing on forest raptors is required for

conservation purposes. Studies predicted the effect of

land clearing on forest raptors using statistical

models. A dynamic model was

constructed by Jiménez-Franco et al. after studying

the nesting platforms of the Booted Eagles, Common

Buzzards, and Northern Goshawks (Franco et al.,

2018). Stimulation shows that populations have a

gradual decrease in clearcutting trees of 50-70 years

old, and populations become extinct for the

clearcutting of 40-year-old trees. Mozgeris et al.

predicted the habitat availability of Estonia's boreal

forest in the coming decades based on current forestry

practices (Mozgeris et al., 2021). With more timbers

maturing and available for harvesting, clearcutting

areas will increase, causing the decrease of nesting

habitat for lessor spotted eagles, disturbance during

Impacts of Deforestation on Forest Raptors and Conservation Strategies

breeding seasons, and may increase interspecific

competition with other species (Franco et al., 2018).

4 CONSERVATIONAL METHODS

4.1 Eucalypt Forest Plantation

With much evidence pointing out habitat loss and

degradation as the most significant threats to forest

raptors, creating or transforming regions into suitable

habitats is one conservation method to protect raptors'

abundance and species richness. By planting woody

plants, the availability of potential nesting and

breeding sites increases in the hope of sustaining a

larger raptor community.

Eucalypt trees are extensively planted in

southwestern Europe for agroforestry purposes, and a

study by Monteagudo et al. examined the habitat

preferences of raptors and results concluded that

eucalypt forests are suitable breeding habitats for

forest-dwelling raptors and are beneficial to raptor

conservation (Monteagudo et al., 2024).

Monteagudo, et al.'s evaluation, shows that the main

driver for habitat preference is vegetation features,

especially for territorial species, and the tall eucalypt

trees fit to be ideal nesting woody vegetation for

breeding pairs (Monteagudo et al., 2024). With the

appropriate size of the central fork, size of tree

crowns, amount of concealment from the canopy, and

sufficient tree height to support tall nests, eucalypt

trees became the primary preference for establishing

nests for many species. Thus, eucalypt forests can

hold dense breeding pairs with fair spatial distribution

distances.

Eucalypt forests as conservation strategy can be

investigate further for improvement. The plantation

of intervention plots should be included within large

forest patches for optimal conservation results. The

plots' distances should vary to target different species,

with species like goshawks with greater distance apart

and smaller species with shorter distances to

minimize interspecific competitions, and the key to

conservational success is low exploitation of forests

in the long term.

The habitat provided by these non-native eucalypt

plants is no doubt beneficial to raptors; however, as a

limitation mentioned in the study, the eucalypt trees

may have adverse effects on small native birds,

causing biodiversity loss. To further expand this,

non-native plants thriving in foreign ecosystems

could be detrimental to many native species. The

benefits to the raptor community are observable as

raptors are larger fauna and top predators. However,

subtle shifts in ecosystems at lower trophic levels

could go unnoticed and may cause long-term

repercussions for other organisms. For instance, the

long-term effects of the accelerated expanding range

of eucalypt forests are unknown, and the changing

composition of plant species may alter nutrient

cycles. The nutrient cycling process is the underlying

basis for energy and production that allows the

thriving of many trophic levels. Forest ecosystems

have longer element cycles for some essential

nutrients and have extensive transit time, with

Phosphorus requiring over 450 years of transit time

and Nitrogen 85 years in eucalypt forests (Spohn and

Sierra, 2018). Concentrations of nutrient elements

strongly influence the primary production of plants,

indirectly affecting the diet and population of

consumers like herbivores and insects and extending

the impacts to higher trophic levels (Clark et al.,

2013), causing an ecological cascade that profoundly

affects ecosystems.

Introducing exotic plantations is an emergent

factor for the ecosystem that may pose potential

effects that cannot be observed in the short term.

Therefore, choosing to plant eucalypt plots for the

sole purpose of raptor conservation may not be

appropriate. More research on the relationship

between eucalypt forests and native biodiversity

should be conducted before transforming landscapes

and implementing large numbers of eucalypt plots.

4.2 Artificial Nests

Björklund et al. evaluate the effectiveness of artificial

nests in conserving three species of forest-dwelling

raptors in Finland (Björklund et al., 2013). The study

results show that the Northern Goshawk and

Common Buzzard have lower breeding success for

artificial nests than natural nests. In contrast, honey

buzzards have the same nesting success regardless of

the type of nest. This result indicates that raptors have

higher nesting failures when using artificial nests, but

artificial nests still support the population.

Concerns were stated in the paper that artificial nests

might act as ecological traps that lure breeding raptors

from natural nests to artificial ones and reduce their

reproduction success; another issue stated is that

artificial nests may favor some species over others.

Indeed, this could lead to intensified interspecific

competition among some species, and some species

may become more dominant. The consequences of

irresponsible nest placement would be

reduced biodiversity and species richness.

However, despite the limitations, this

conservation method is economically efficient and is

ICREE 2024 - International Conference on Renewable Energy and Ecosystem

able to ease the problem of lacking nesting sites in the

short term. It is time- and resource-consuming to

restore a young forest to maturity actively. The effects

of implementing artificial nests are immediate

without requiring the woody vegetation to take years

to develop tree crowns and forks that are large enough

to attract raptors to nest; therefore, this conservation

method is practically appropriate.

To minimize the effect of human intervention on

the species composition of raptors, the ecology and

nesting habits of all raptors in the area should be

studied and evaluated before the placement of

artificial nests. The production of artificial nests

should consider species preferences, for instance,

providing a range of sizes and materials to

accommodate different raptors and prioritizing to

conserve more vulnerable species or species with

intrinsic value. The location and distance of the

implementation should also be considered. Some

species have preferred elevation in landscapes, and

with highly territorial species, distance between

nests is recommended to reduce intraspecific

competition and utilize home ranges.

5 CONCLUSION

This paper discusses the effects of deforestation on

forest raptors and evaluations of two possible

conservation methods. In general, non-migratory

raptors that are reliant on forests are more vulnerable

to habitat degradation. The complexity of maturity of

old-growth forests provides exceptional habitat for a

diversity of forest raptors. With high-density prey

abundance, lateral spatial sites for hunting, and high

biodiversity of animals sustaining specialist species,

forest raptors thrive in large, intact patches of forests.

Mature trees also provide suitable trunks and crowns

for raptors to construct nests, allowing raptors to

breed and raise their young.

With ample evidence showing that deforestation

that caused habitat degradation and fragmentation is

the biggest threat that raptors face, conservation

methods should be evaluated based on species

susceptibility, raptor's diet requirements, and nesting

preferences. The key to sustaining healthy raptor

populations and species diversity is the preservation

of intact, mature forest ecosystems.

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