Main biodiversity monitoring subjects in transport infrastructure

Monitoring plans of transport infrastructure projects, depending on the context, can focus in a wide diversity of topics, target species, habitats and ecosystems. The goal of this section is not describing in detail methods to be applied in all these different context but to show the diversity of techniques that could be applied to gather data on the field. Although the most common techniques are presented, this not a comprehensive list. These techniques are evolving very rapidly and therefore, expert ecologists are required to identify which are the most suitable techniques according to the goals and targets for each monitoring plan at the time of developing a new monitoring plan.

The most common targets for monitoring in the infrastructure right-of-way, where habitats related to transport infrastructure (HTI) are found, and other affected areas are: 

• Habitats and species lists (presence/absence)
• Species distribution and abundance
• Habitat mapping (location, extent, and ecological condition)
• Wildlife movements, migratory patterns and other behavioural studies (e.g., use of wildlife passages to cross roads and railways, flight patterns across powerlines and other)
• Genetic diversity at population or landscape scale (DNA is also used to provide information about species presence)
• Demography (variation in size or structure of populations affected by infrastructure barriers).

Techniques applied differ from species or taxonomic groups (Table 6.1), and depending on the goal of monitoring, also in the technology to be used, and other variables (Table 6.2). Relevant references and links to further information about these technologies can be found in Section 6.4. References.

Other topics which are specific to transport infrastructure monitoring are:

• Wildlife mortality by traffic or infrastructure (by traffic, collision with powerlines or railways catenaries, birdstrike in airports, drought and other causes related with transport infrastructure operation): identification of species and hotspots of mortality.
• Invasive Alien Species: identification of species, distribution, eradication and control techniques, and their effects on humans and species in HTI and adjacent habitats.
• Effects of noise, light and other disturbance on presence/absence and movement behaviours of wildlife in HTI and adjacent habitats.
• Effects on hydrology: how the infrastructure affects the course of rivers or wetlands and the natural hydrological regimes including risk of floods or landslides.
• Effects linked to climate and global change including topics such as: adaptation of HTI vegetation to drought or forest fire propagation.
• The ‘One health’ approach: risk of disease spread risk to human, cattle and wildlife, effect of pollutants in human and wildlife health.
• Synergic cumulative effects of different infrastructure in one area. 

Table 6.1 – Summary of most common monitoring techniques to collect biodiversity data in the field for each target group . ‘●’ Optimal; ‘o’ To be used with some adaptation; ‘-‘ Not suitable; ‘?’ Unknown.

Technique

Invertebrate

Fish and other aquatic fauna

Amphibians

Reptiles

Birds

Small mammals

Medium mammals

Large mammals

Semiaquatic mammals

Arboreal mammals

Bats

Natural habitats

Flora species

Track bed (fine sand or similar material)

–

–

?

?

o

?

o

o

?

?

–

–

–

Artificial shelters / nests with cameras

●

–

●

●

●

●

●

–

o

o

●

–

–

Field inventories/ direct observation

●

●

●

●

●

●

●

●

●

●

●

●

●

Snow tracking

–

–

–

–

–

–

o

o

o

o

–

–

–

Hair / feather trap

–

–

–

–

●

●

●

●

●

●

–

–

–

Camera trap (PIR/motion sensor)

?

–

?

?

o

o

●

●

●

●

o

–

–

Camera trap (time lapse)

o

–

●

●

–

●

●

●

o

o

?

–

–

Thermal camera

–

–

?

?

o

o

●

●

●

●

o

–

–

Visual amplification device

–

–

o

o

●

o

●

●

o

●

o

–

–

Drones with sensors

?

?

?

?

●

?

o

●

●

●

o

●

?

Capture-Mark- recapture

–

–

o

o

o

●

●

●

●

●

●

–

–

Bioacoustics device

●

●

●

–

●

●

●

●

●

●

–

–

–

Radiotracking

o

●

●

●

●

●

●

●

●

●

?

–

–

Radar detection devices

o

–

–

–

o (large)

–

–

o

–

–

–

–

–

Satellite-based techniques

–

–

–

o

●

●

●

●

●

●

●

●

?

eDNA

●

●

●

o

o

o

●

●

●

o

o

–

o

Genetic landscape

●

●

●

●

●

●

●

●

●

●

●

–

o

Table 6.2 – Main characteristics of potential monitoring techniques applied to collect data in the field. Recommendation regarding adequacy is given based on different characteristics considered. ‘Concision’: giving only the information that is necessary and important; ‘Prospection effort’ time required to collect the information; ‘Maturity level’: degree of development of the technique; ‘Cost’: budget required.

Technique	Concision	Prospection effort	Maturity level	Cost
Track Bed (fine sand or similar)	Low	Low	High	Low
Artificial shelters / nests with cameras	Medium	Low	High	Medium
Field inventories/ Direct observation	High	High	High	Low
Snow tracking	Low	Medium	High	Low
Hair (feather) trap	High	Low	High	Low
Camera trap (PIR/motion sensor)	High	Low	High	High
Camera trap (time lapse)	High	Low	High	High
Thermal camera	Low	Low	Low	High
Visual amplification device	High	Low	High	Medium
Drones with sensors	High	Low	Low	Medium
Capture-Mark-Recapture	Medium	High	High	Medium
Bioacoustics devices	Medium	Low	Low	Medium
Radiotracking	High	Medium	High	Low
Radar detection devices	Medium	Low	Low	High
Satellite-based techniques	Medium	Low	Medium	High
eDNA	Medium	Low	High	High
Genetic landscape	Medium	Low	High	High