Barriers of Passage

Until we have a good sense of which dangers cause the most damage, this section is listed alphabetically. Coincidentally it does seem like they might accidentally be listed from worst offenders to lesser offenders, since light travels the furthest and causes problems spreading out into our oceans and distant forests, luring birds, insects, and turtles away from safe habitats. Farm land accounts for about 50% of Earths habitable pace, so fencing could likely be the second worst offender. Roads are widespread, so they may be almost equal to fencing in their harm (though possible worse?). Traps are meant to kill or can cause victims to starve, but they may be more of a problem than people realize when accounting for ghost nets and other fishing gear clocking our waterways, lakes, and oceans.

EMFs

Countries around the world are switching to HVDC and HVAC cables for their major electricity projects, but unfortunately these give off EMFs which can influence the migration patterns and other behaviors of marine life. - https://www.osti.gov/servlets/purl/1633088 

Fake Spider Webbing

The fake spider webbing that people put up as decoration during Halloween is made from synthetic fibers which entrap a variety of species including birds (especially owls), bees, butterflies, and squirrels.

If you are going to use the decoration, then keep it close to the front door or other highly-visible, high-traffic areas so that any animals will be seen and helped quickly, instead of dying slowly in hard-to-reach places. Any live animals should be taken to a wildlife rehabilitation center.

Other safer places including indoors and around windows. Never hand the fake webbing across wide areas, such as between trees or over bushes where wild animals are most likely to get entangled.

Light Pollution

Can lure, blind, startle, and scare animals from their habitats or migratory routes. Baby turtles go inland towards cities and roads instead of out to see, following the moon and stars. Migratory birds can be dazzled by bright lights, lasers, fireworks, blinking lights, and flood lights. Insects have flooded into cities like Las Vegas, lured by the lights, then died in mass numbers in the streets instead of performing their job as food for species in the surrounding wilderness.

Fences & Walls

Farms & Ranches

General Borders on the Rise

Borders on the Rise: The Unintended Evolutionary Consequences of Border Barriers on Natural Populations "Human-made barriers reduce animal movement and gene flow through multiple mechanisms, including changing movement directly by physical obstruction and indirectly through behavioral avoidance, or by killing migrants through entanglement (i.e., getting tangled or caught in a barrier) and direct strikes (i.e., hitting a barrier directly, which causes injury and death). These mechanisms can operate independently or in combination to reduce gene flow between populations separated by a barrier."

Traps

The Dangers of Glue Traps "Each year, countless animals are unintentionally caught in glue traps or “glue boards”. Glue traps are typically sheets or tubes covered in an extremely sticky glue; the traps are traditionally meant to capture flying insects, like wasps or flies (when hung up high) or rodents (when placed on the ground).

When an insect or animal is caught in this trap, its death is not quick or painless. Often, the animal struggles against the glue in an attempt to free itself, and eventually succumbs to injuries, exhaustion, starvation, or dehydration during a period of a few hours or several days.

Sticky traps are indiscriminate and often catch animals that are the unintended victims of the trap – typically birds, snakes and lizards, and small mammals. In the cases of wider glue boards, even larger mammals have been stuck to traps and suffer injuries or fur loss when pulling free.

When hung outside of a home or in a barn, these traps (often in the form of tubes or strips of paper) catch not only wasps, but other flying animals, such as owls, bats, flying squirrels, and songbirds who accidentally fly into the glue trap, sometimes in an attempt to eat the insects that are stuck to the glue."

Solutions

Darkness

Bright lights can startle and disorient many wild species including bats (who help us by eating between 1,000 to 4,000 insects per night), migratory birds, moths who pollinate our food, and fireflies who eat problematic bugs like slugs and snails. Some species will totally avoid lit areas, barring them from food, water, and migratory routes, while others are attracted to lights. These species will fly into suburban areas where they can easily be injured, disoriented, lost, or even killed.  Artificial lights can act as lures which make endangered species easy targets for their predators.

Fencing & Boundaries

• Avoid fencing areas if possible (for example if you have no dogs). Hedge rows and walls can provide useful habitats, but the dissection of habitats can cause animals to starve or suffer genetic diversity loss.

• Low fences can allow large animals like deer to migrate.

• Raised fences or fences with gaps underneath can allow small animals to pass.

• Install a port hole for small or medium-sized animals.

• Hedge rows can help block light and provide privacy, while allowing smaller animals to pass through. Hedges also increase "edge effect" which is known to increase biodiversity.

• Remove old and unnecessary fencing.

Frog Solutions

Guidelines for Creating & Upgrading Wildlife-Friendly Crossings

• Coastal Roadway Lighting Manual (PDF) "A Handbook of Practical Guidelines for Managing Street Lighting to Minimize Impacts to Sea Turtles 

• Guidelines for Culvert Construction to Accommodate Fish & Wildlife Movement and Passage (PDF) "This document is intended as a general guideline to assist in the design, planning, and placement of culverts to minimize impacts to and ensure fish and wildlife passage and movement."

• Fish Friendly Culverts (PDF) Proper design, installation, and maintenance can protect both roadways and fish" Includes graphs, maps, and suggestions for sources of assistance.

• Fish-stream Crossing Guidebook (PDF) "The purpose of this revised guidebook is to help forest and other resource managers and practitioners plan, prescribe, and implement sound fish-stream crossing practices to maintain fish passage and protect fish and fish habitat as required by the Forest and Range Practices Act and the federal Fisheries Act. It provides practitioners with current legislative and technical reference material regarding fish passage, including British Columbia’s strategic approach to addressing fish passage at culverts. ... As noted above, the guidebook also identifies a strategic approach for preCode structures that encompasses a holistic procedure to assess culverts for passage of fish, including all structures regardless of age or origin of the problem. The guidebook sets the standard for a process of prioritization that all land managers can use in determining remediation plans. "

• Stream Crossings in Georgia: A Handbook for Connectivity and Resilience (PDF) "This handbook is intended to encourage the proper design and implementation of all new stream crossings in Georgia to maintain stream connectivity, improve stream health, provide for public safety, improve water quality and make communities more resilient."

• Wildlife Crossings Providing Safe Passage for Urban Wildlife (PDF) "This guidebook complements the previous and ongoing work of Metro, including Metro’s Green Streets, Trees for Green Streets, Creating Livable Streets and Green Trails guidebooks as well as the work of others in the Portland metropolitan area focused on inventorying, characterizing, and connecting important habitats for native fish and wildlife."

• Wildlife Crossing Structure Handbook: Design and Evaluation in North America (pdf) "This handbook is organized to provide assistance to transportation and natural resource management practitioners charged with the planning, design and performance evaluations wildlife crossing mitigation. This handbook was designed so that chapters could be consulted independently, depending on the information or technical guidance needs, or all chapters in a practical sequence of project development."

Stepping Stone Ponds

One study of the European tree frog (Hyla arborea) found that "Collecting buccal material of 85 frogs sampled at newly built stepping-stone ponds, we identified source populations of migrating frogs by means of 11 microsatellite markers. Results show that new ponds were colonized within one year, and that the number of colonising frogs increased with the new ponds' age. Some migrating individuals originated from small or distant populations (up to 5 km), and even crossed expected barriers such as a river. The landscape in the study area appeared thus quite permeable to tree frogs. Our measures revealed that building new stepping-stone breeding ponds is an efficient and successful conservation action."

Trap Removal

Trap removal can be dangerous work, but it's important. Some organizations rely on volunteers, while others pay villagers or other at-risk people to remove traps including ghost gear (lost or dumped fishing nets, lobster traps, fishing lines and hooks, etc.).

South America

South America Wildlife Migrations this isn't a map, but a list of species that migrate and which South or Central American countries they pass through or migrate to.

Studies

• Bird Movements and Behaviors in the Gulf Coast Region: Relation to Potential Wind Energy Developments, November 22, 2000 – October 31, 2005  (pdf)

• Environmentalism in the crosshairs: Perspectives on migratory bird hunting and poaching conflicts in Italy " Migratory bird hunting has a long tradition in the Mediterranean, but remains a highly controversial issue. Here we examine the Mediterranean migratory bird hunting controversies through the case of Italy. We interviewed key informants and carried out participant observation on both legal and illegal migratory bird hunting and migratory bird protection, in four key migratory bird hunting sites in Italy. In many cases, both migratory bird hunters and bird protection activists consider themselves as the stewards of nature. Environmentalists accuse hunters of illegal practices, while hunters believe anti-poaching activists aim to threaten the existence of hunting itself. Yet surprisingly, the legality of specific hunting practices emerges as peripheral to the concerns of both groups. The lack of dialogue and increasingly polarized positions on both sides make it difficult to assure compliance with EU and national migratory bird hunting laws, and hinders finding shared solutions that consider differing values in a rapidly changing society."

North America